31,480 results on '"thermoplastics"'
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2. When the Trend Comes to You: With roots in recycling, Star Plastics produces engineering thermoplastic compounds to meet performance and environmental goals
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Stonecash, Matt
- Subjects
Environmental engineering ,Thermoplastics ,Business ,Chemicals, plastics and rubber industries - Abstract
Manufacturers turn to engineering resins when high performance, flame retardance or robustness to harsh environments are required. Star Plastics meets these needs with its custom compounds, which include ABS, nylon [...]
- Published
- 2024
3. Room‐temperature self‐healing polyurethanes with high mechanical strength and superior toughness for sensor application.
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Yin, Xingshan, Huang, Zhiyi, Liu, Xiaochun, Sun, Yingjuan, Lin, Xiaofeng, Lin, Wenjing, and Yi, Guobin
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ELECTRONIC equipment ,ZINC ions ,TENSILE strength ,POLYURETHANES ,WASTE recycling ,POLYURETHANE elastomers - Abstract
It remains enormous challenges to balance the conflict between high strength and toughness mechanical properties and excellent room‐temperature self‐healing abilities of polyurethane elastomers. In this work, we report a recyclable room‐temperature self‐healing polyurethane elastomer with excellent mechanical properties. The prepared polyurethane elastomer (PU‐DA‐Zn0.50) exhibits high tensile strength of 15.33 MPa, high toughness of 76.77 MJ m−3, and high elongation at break of 1604.46% by introducing isophorone diamine (IPDA), 1‐(3‐aminopropyl) imidazole (IMZ) and zinc ions into polymer system to form a dynamic double‐cross‐linked structure (hydrogen bonds and Zn2+‐imidazole coordination bonds). In addition, the tensile strength of fractured polyurethane can reach more than 80% of the original sample after 48 h of self‐healing at room temperature without external stimuli, which is attributed to the kinetics of rapid exchange of Zn2+‐imidazole coordination bonds at room temperature. It is worth noting that the balance between excellent mechanical properties and outstanding room‐temperature self‐healing ability can be optimized by adjusting the Zn2+‐imidazole coordination bond density in the system. Moreover, the dynamic nature of the double‐cross‐linking network endows polyurethane with favorable recyclability. The above remarkable comprehensive performances reveal a great potential of PU‐DA‐Znx elastomer in the fields of wearable flexible electronic devices such as bionic skin, human motion monitoring, and soft robots. [ABSTRACT FROM AUTHOR]
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- 2024
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4. Self‐lubricating polyamide 6 and polyamide 6.6 microcapsule‐based composites.
- Author
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Grünewald, Moritz, Herbig, David, Heilig, Michael, Rudloff, Johannes, Bastian, Martin, Engelmann, Gunnar, Hirsekorn, Max, and Latnikova, Alexandra
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CORE materials ,MECHANICAL wear ,POLYMERIZATION ,POLYAMIDES ,SERVICE life - Abstract
Polymeric applications with extended service life and low energy loss due to friction are of great interest in conveyor and power transmission technology. Self‐lubricating systems utilizing microcapsules hold significant potential for increasing energy efficiency and extending the operational life of these applications. This study focuses on synthesizing oil‐filled microcapsules through in situ polymerization of polyamide and their incorporation in polyamide 6 and polyamide 6.6. Microcapsules with a core made of thermally stable lubricant Food Lube, and particle diameter D90 of 50 μm were synthesized and isolated as a free‐flowing powder via spray‐drying procedure. The resulting powder demonstrated high thermal stability (loss of 5% at 350°C) due to the high thermal stability of both core and shell materials. A compounding process utilizing a twin‐screw extruder was developed to blend microcapsules into thermoplastic matrices. An injection molding machine forms tension rods. The composites' tribological properties are assessed through ball‐on‐disc tests conducted in both oscillation and rotation. The friction coefficient and wear rate of the composites experience a reduction of 79% and 56% for polyamide 6, as well as 77% and 75% for polyamide 6.6. Mechanical testing of the microcapsule composites reveals a decrease in mechanical properties. [ABSTRACT FROM AUTHOR]
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- 2024
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5. Fracture toughness and failure behavior of CF/epoxy composites interleaved with melt‐infused PET, PEI, and PEEK film.
- Author
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Too, Daniel Kipkirui, Kumar, Sanjay, and Kim, Yun‐Hae
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MATERIAL plasticity , *DEFORMATIONS (Mechanics) , *CARBON films , *FRACTURE toughness , *COMPOSITE structures - Abstract
This study investigates the effect of incorporating polyethylene terephthalate (PET), polyetherimide (PEI), and polyether‐ether‐ketone (PEEK) thermoplastic films in melt form as interlayers to toughen carbon fiber/epoxy composites. The addition of melt‐infused PET, PEI, and PEEK film into carbon fiber/epoxy composite enhanced the mode‐I interlaminar fracture toughness (ILFT) by 60%, 156%, and 284%, respectively. The primary toughening mechanisms found were plastic deformation and mechanical interlocking through fiber bridging, which left fiber imprint traces on the fracture surface. The mode‐II ILFT of PET, PEI, and PEEK film interleaved laminates was improved by 80%, 188%, and 96%, respectively. Plastic deformation was observed to be the principal toughening mechanism. Notably, these enhancements in ILFT were achieved while simultaneously increasing interlaminar shear strength. These findings show the role of hot‐melt‐infused PET, PEI, and PEEK thermoplastic films in the improvement of ILFT of composites which is crucial in the design of damage‐tolerant composite structures. Highlights: Composites were interleaved with PET, PEI, and PEEK films via melt‐infusion.Mode‐I and mode‐II ILFT were significantly enhanced, up to 284% for PEEK.Failure exhibited plastic deformation, extensive fiber bridging, and pull‐out.Melt‐infusion created complex, mechanically interlocked interfaces. [ABSTRACT FROM AUTHOR]
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- 2024
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6. Fully recyclable and tough thermoplastic elastomers from simple bio-sourced δ-valerolactones.
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Ma, Kai, An, Hai-Yan, Nam, Jiyun, Reilly, Liam T., Zhang, Yi-Lin, Chen, Eugene Y.-X., and Xu, Tie-Qi
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THERMOPLASTIC elastomers ,WASTE recycling ,THERMOPLASTICS ,DEPOLYMERIZATION ,MONOMERS - Abstract
While a large number of chemically recyclable thermoplastics have been developed in recent years, technologically important thermoplastic elastomers (TPEs) that are not only bio-based and fully recyclable but also exhibit mechanical properties that can rival or even exceed those petroleum-based, non-recyclable polyolefin TPEs are critically lacking. The key challenge in developing chemically circular, bio-based, high-performance TPEs rests on the complexity of TPE's block copolymer (BCP) structure involving block segments of different suitable monomers required to induce self-assembled morphologies responsible for performance as well as the control and monomer compatibility in their synthesis and the selectivity in their depolymerization. Here we demonstrate the utilization of bio-sourced δ-valerolactone (δVL) and its simple α-alkyl-substituted derivatives to produce all δVL-based polyester tri-BCP TPEs, which exhibit not only complete (closed-loop) chemical recyclability but also excellent toughness that is 2.5–3.8 times higher than commercial polyolefin-based TPEs. The visualized cylindrical morphology formed via crystallization-driven self-assembly in the new all δVL tri-BCP is postulated to contribute to the excellent TPE property. While a large number of chemically recyclable thermoplastics have been developed in recent years, technologically bio-based and fully recyclable thermoplastic elastomers (TPEs) with excellent mechanical properties are lacking. Here the authors demonstrate an all δvalerolactone-based polyester tri-BCP TPEs, which exhibit not only closed-loop chemical recyclability but also exceptional toughness. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Welding of Parts Made of Polymer Composite Materials Based on Thermoplastics. Part 3. Methods for Welding Parts Made of Polymer Composite Materials Based on Thermoplastics with the Conversion of Various Types of Energy.
- Author
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Nefelov, I. S. and Baurova, N. I.
- Abstract
This article is a continuation of a series of articles on welding parts made of polymer composite materials based on thermoplastics. Methods for welding plastics based on thermoplastics with the conversion of various types of energy into heat and their classification are considered. The features of friction welding, ultrasonic welding, high-frequency welding, and radiation welding technologies are given. The main parameters of technological modes of the considered welding methods, areas of their use, and advantages and disadvantages are determined. [ABSTRACT FROM AUTHOR]
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- 2024
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8. Neue Perspektiven.
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Leitner, Mario
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WELDING ,THERMOPLASTICS ,AUTOMOBILE industry ,AEROSPACE industries ,MANUFACTURING processes - Abstract
The article presents Plastics Metal Stir Welding (PMSW) as a groundbreaking technique from Royos Joining Solutions GmbH that enables the durable connection of various thermoplastics with metals, significantly enhancing production efficiency and material versatility in industries like automotive and aerospace. It states that this innovation allows for reliable welding without the need for pre-treatment, streamlining the manufacturing process.
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- 2024
9. Adhesion‐controlled anisotropic rotational molding of multilayered ultrasoft silicone films.
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Kaufmann, Anke, Schlicht, Samuel, Rösel, Uta, and Drummer, Dietmar
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MANUFACTURING processes ,THERMOPLASTICS ,SILICONES ,SPEED ,ELECTRONS - Abstract
Rotational molding allows the manufacturing of geometrically complex, hollow parts while maintaining low tool costs. While the rotational molding of thermoplastics is subject to inherent limitations regarding the wall thickness and processing of ultrasoft materials, the present paper introduces the adhesion‐controlled, highly dynamic rotational molding of room‐temperature curing resins, enabling the fabrication of thin, multilayered films and anisotropic, ultrasoft silicone components at rotational speeds up to 2000 min−1. The studies comprise the influence of the applied rotational speeds and the different molds. Based on scanning electron micrographs, the process is shown to allow for locally tailored part thicknesses, enabling the manufacturing of multilayered films with singular layers obtaining thicknesses below 10 μm. Relying on the control of emerging centripetal forces, the rotational speed depicts a quasi‐linear influence on resulting layer thicknesses, allowing for controlling the film thickness with excellent interlayer bonding. Relying on the superposition of consecutive layers, the adhesion‐controlled process allows for tailoring emerging nonlinear, ultrasoft stress–strain behaviors across a broad range of desired moduli. Conducting compression tests, increased rotational speeds are shown to reduce the part stiffness, attributed to the increased relative influence of interlayer interfaces, allowing for reproducing mechanical characteristics similarly found in ultrasoft human soft tissue. Highlights: Highly dynamic rotational molding of ultrasoft thin films.Targeted anisotropic structure formation.High geometric accuracy and reproducibility of thin silicone films.Targeted adaptability of nonlinear compressive mechanical properties.Applicability for ultrasoft laryngeal implants. [ABSTRACT FROM AUTHOR]
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- 2024
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10. Hot melt thermoset/thermoplastic hybrid prepregs: Effects of B‐stage conditions on the quality of composite parts.
- Author
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Nohair, Bendaoud, Dufresne, Stéphane, Poirier, Daniel, Turgeon, Mathieu, and Elbouazzaoui, Sanaa
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SURFACE finishing , *HYDRAULIC presses , *THERMOPLASTICS , *RHEOLOGY , *CONSUMERS - Abstract
Highlights Prepregs are highly expensive, and most customers rely heavily on suppliers. The product may not always be optimized for specific applications, but it is sometimes the only commercially available option that works. To address these issues, there is a need to produce prepregs in‐house. In this article, we will describe the methodology for creating thermoset/thermoplastic hybrid prepregs using hot melt with B‐stage cured epoxy resin film. We investigated the choice of materials and the proportion of thermoplastics through DSC and rheology measurements. Additionally, we analyzed the time and temperature of B‐staging to achieve high‐quality composite parts. Multiple ways for preparing prepregs exists, each involving few different steps. We will explore some of these methods using a hydraulic press before scaling up to a prepreg filmer machine. Our focus will be on evaluating the quality of the final composites under various conditions and comparing them to composites produced with commercially available prepregs. In‐house thermoset/thermoplastic hybrid prepreg fabrication optimization procedure. Material characterization prior to fabrication to ensure B‐staging repeatability. Investigation of several methods of prepreg fabrication. Optimized procedure to achieve high‐quality surface finish for composite parts. [ABSTRACT FROM AUTHOR]
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- 2024
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11. Efficient identification of a flow-induced crystallization model for injection molding simulation.
- Author
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Saad, Sandra, Cruz, Camilo, Régnier, Gilles, and Ammar, Amine
- Abstract
Most commercial software used to simulate the injection molding process of semi-crystalline thermoplastic polymers do not explicitly take into account the polymer crystallization, which could lead to errors in the estimations of filling as well as warpage and shrinkage. This is mainly due to the common complexity of the models used to describe crystallization and the challenging respective model parameter identification under injection molding conditions. To close this gap, in this work, we use a simple thermo-mechanical crystallization model to describe the flow-induced and quiescent crystallization of an unreinforced semi-crystalline thermoplastic material during injection molding. The crystallization model is implemented in the commercial software Autodesk® Moldflow® Insight 2021 using the Solver API feature alongside crystallization-dependent viscosity, PVT, and solidification models. The model parameters were identified using a calibration workflow that employs surrogate models representing the simulated pressure results to perform a multi-objective optimization. The filling predictions as well as the calculated pressure fields are presented using the calibrated model parameters in comparison to those measured during the actual injection molding of a polyoxymethylene (POM) part using different process conditions. The results show major improvements in the estimations of the time-depending pressure field as well as the level of filling of the produced parts. [ABSTRACT FROM AUTHOR]
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- 2024
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12. Characterization of self‐reinforced polyethylene recyclates according to different valorization strategies.
- Author
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Roiron, Coline, Lainé, Eric, Grandidier, Jean‐Claude, Garois, Nicolas, Voillequin, Baptiste, and Vix‐Guterl, Cathie
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POLYETHYLENE ,ENERGY consumption ,WASTE recycling ,ECOLOGICAL impact - Abstract
In the context of the energy transition, especially in the automotive and aerospace fields, specific attention must be paid to energy consumption and carbon footprint reduction throughout the life cycle of parts. Composites such as self‐reinforced polymers (SRPs) appear as an interesting alternative by combining the components' lightness, mechanical strength, and similar chemical nature. This last point makes recycling possible without any costly separation step of the constituents. The literature has widely reported the easy recyclability of SRP as a development driver. However, few studies analyze it in detail. The feasibility of reprocessing by mechanical grinding a self‐reinforced polyethylene (SRPE) is then examined to view two valorization routes. The impact of the thermomechanical history undergone before recycling, the grinding, the nature of the shreds, and the reprocessing conditions, on the behavior of the recyclates is studied, in parallel with physical considerations, for one reprocessing cycle. The results obtained show that SRPE can be mechanically recycled and keep interesting mechanical properties whatever its reuse. [ABSTRACT FROM AUTHOR]
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- 2024
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13. The influence of mold design and process parameters on dimensional shrinkage of perfluoroalkoxy alkane injection molding parts.
- Author
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Li, Xuemei, Liu, Fan, Zhang, Chengqian, Gao, Ruoxiang, Xu, Xiao, Fu, Jianzhong, and Zhao, Peng
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INJECTION molding ,MASS production ,ALKANES ,TAGUCHI methods ,FLOW simulations ,DESIGN - Abstract
In mass production, injection molding plays a vital role in manufacturing various parts with complex settings. As perfluoroalkoxy alkane (PFA) injection‐molded products are widely used in immersion system, dimensional quality needs more attention. However, there is limited research on the dimension defects of PFA injection‐molded products. This study focused on the influence of mold design and process parameters on PFA part shrinkage, using mold flow simulation and orthogonal testing separately. Several gate locations and sizes were simulated to minimize shrinkage in mold design. Displacements varied with gate locations, and shrinkage decreased with larger gate sizes. The Taguchi method analyzed process parameters' impact on shrinkage. The results indicated that the injection rate had the most significant effect on the shrinkage of tube length, while melt temperature, holding pressure, and screw speed affected the shrinkage of tubes' outside diameter. Different flow directions exhibited variance in shrinkage. Using max–min normalization, the two shrinkage values reached 0.00972, whereas the smallest value obtained in the orthogonal experiment was 0.1545 in run 3. Thus, optimizing mold design and process parameters were two effective methods to reduce shrinkage. This study reduced shrinkage and improved the quality of PFA injection molding parts for semiconductor systems. [ABSTRACT FROM AUTHOR]
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- 2024
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14. Characterization of relaxation behaviour of CF/PEKK aerospace composites using the time-temperature-crystallinity superposition principle.
- Author
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Al-Dhaheri, Mariam A., Cantwell, Wesley J., Barsoum, Imad, and Umer, Rehan
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STRAINS & stresses (Mechanics) , *SUPERPOSITION principle (Physics) , *DIFFERENTIAL scanning calorimetry , *MELT crystallization , *RESIDUAL stresses - Abstract
In this study, the Time-Temperature-Crystallinity Superposition Principle (TTCSP) was applied to determine the viscoelastic behavior of Thermo-rheological Complex Materials (TCM), specifically Carbon fibre/Poly-Ether-Ketone-Ketone (CF/PEKK) composites. The study investigated the effects of various parameters on the viscoelastic behavior of the composites, such as the degree of crystallinity after different melting temperatures, relaxation, and crystallization times. The TTCSP was utilized on the relaxation data to generate great-grand master curves for the degree of crystallinity for different laminate lay-ups. Hot press forming was employed to manufacture samples under different processing conditions, including various melting and cold crystallization temperatures. Differential Scanning Calorimetry (DSC) was employed to calculate the degree of crystallinity of CF/PEKK composites, while the Dynamic Mechanical Analyzer (DMA) was used to obtain the relaxation data. The generated great-grand master curves proved effective in predicting the relaxation behavior of the composites consolidated using single and double hold cycles at different melting temperatures and crystallization times, respectively. The great-grand master curves presented in this study can serve as valuable tool to calibrate key viscoelastic and/or thermo-viscoelastic material models for aerospace-grade CF/PEKK composites. These models are crucial for simulations aimed at predicting residual stresses and process-induced deformations during the thermoforming process. [ABSTRACT FROM AUTHOR]
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- 2024
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15. Oil Plant Pomace as a Raw Material in Technology of Sustainable Thermoplastic Polymer Composites.
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Lipska, Karolina, Betlej, Izabela, Rybak, Katarzyna, Nowacka, Małgorzata, and Boruszewski, Piotr
- Abstract
The design of composites offers extensive opportunities for controlling parameters and utilizing diverse materials, including those sourced from recycling or waste streams. In this study, biocomposites were developed using high-density polyethylene (HDPE) and pomace derived from oilseed plants such as evening primrose, gold of pleasure, rapeseed, and sunflower seeds, mixed in a 1:1 ratio. These biocomposites were evaluated for their structural, mechanical, morphological, and thermal properties, as well as their vulnerability to overgrowth by cellulolytic fungi. The results indicate that incorporating plant waste into HDPE reduces thermal stability while increasing water absorption and thickness swelling. Additionally, the biocomposites showed enhanced fungal growth, which may improve their biodegradability. Notably, the PE_EP composite, derived from evening primrose pomace, did not show significant differences in surface roughness and MOE parameters compared to pure polyethylene. In the case of PE_R composite, an increase in MOE was observed while maintaining the MOR parameter compared to pure PE. Although generally the mechanical properties of composites were lower compared to pure polyethylene, the findings suggest that with further optimization, oil plant pomace can be a valuable raw material for producing biocomposites suitable for various industrial applications, thereby contributing to sustainability and effective waste recycling. [ABSTRACT FROM AUTHOR]
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- 2024
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16. Non‐isocyanate polyurethane‐acrylate as UV‐ and thermo‐responsive plasticizer for thermoplastic elastomer.
- Author
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Lam, Ki Yan, Lee, Choy Sin, Pichika, Mallikarjuna Rao, Cheng, Sit Foon, and Tan, Rachel Yie Hang
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ISOCYANATES ,THERMOPLASTIC elastomers ,POLYURETHANE elastomers ,ACRYLATES ,PLASTICIZERS ,TENSILE tests ,GEL permeation chromatography ,NUCLEAR magnetic resonance - Abstract
A UV‐ and thermo‐responsive polyurethane‐acrylate prepolymer was synthesized from palm olein (POo) via a non‐isocyanate route. The process included epoxidation of POo, carbonation of epoxidized palm olein (EPOo) into polycyclic carbonate in a solvent‐free and mild condition (100°C, 1 atm), followed by reacting with ethylene diamine and acrylic acid. The chemical structure of the non‐isocyanate polyurethane‐acrylate (NIPUA) prepolymer was elucidated by 1H and 13C nuclear magnetic resonance (NMR) and Fourier transform‐infrared spectroscopy (FTIR), while weight average molecular weight of NIPUA was determined by gel permeation chromatography (GPC). The NIPUA (0–20 wt%) was incorporated with thermoplastic elastomer (TPE) as a plasticizer and cured under UV light and thermal stimulations. The cured NIPUA/TPE films were characterized by FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile strength test. Under UV and thermal stimulations, the NIPUA/TPE demonstrated enhanced tensile properties (elongation at break >1280%, Young's modulus ~25 MPa), thermal properties (lower Tg), lower water contact angle, and shortened curing time as compared with the blank TPE. The 20 wt% NIPUA/TPE films exhibited susceptibility to enzymatic biodegradation and noncytotoxic to HEK 293 cells in vitro, demonstrated it's potential as a UV‐ and thermo‐responsive plasticizer for TPE in manufacturing of medical devices. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
17. Thermoplastic polyimide with low dielectric properties enabled by the 2,2′‐spirobifluorene group.
- Author
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Jian, Ling‐Feng, Lu, Zhi‐Yu, Zhang, Jin‐Yuan, Yuan, Hui‐Bo, Zhang, Hui, Ge, Hua, Tan, Wan‐Yi, Cui, Ting‐Ting, and Min, Yong‐Gang
- Subjects
DIELECTRIC properties ,POLYIMIDES ,PERMITTIVITY ,INTERMOLECULAR interactions ,MOIETIES (Chemistry) ,POLYMERS - Abstract
Thermoplastic polyimides (TPIs) have melt‐processability and adhesive ability, besides the intrinsic advantages of polyimides. To meet the requirements of applications in high‐frequency communication, TPIs with low dielectric constant (Dk)/dielectric loss factor (Df) at high frequency are also desirable. Enhancing the rigidity of polymer chains and simultaneously intermolecular interaction are effective ways to ensure low Dk/Df, which also benefit to heat resistance. However, it is not conducive to thermoplasticity, due to limited movement of polymer chains. To balance the trade‐off between them, we introduce noncoplanar 2,2′‐spirobifluorene groups to modify the rigidity of polymer chains and regulate the twist between electron‐donor moieties (diamine units) and electron‐acceptor moieties (dianhydride units). It leads to rigid polymer chains, which benefits to good heat resistance and dielectric properties. Meanwhile, the resultant irregular chain structure is difficult to crystallize, which results in thermoplasticity. [ABSTRACT FROM AUTHOR]
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- 2024
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18. Reprogrammable, Sustainable, and 3D‐Printable Cellulose Hydroplastic.
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Koh, J. Justin, Koh, Xue Qi, Chee, Jing Yee, Chakraborty, Souvik, Tee, Si Yin, Zhang, Danwei, Lai, Szu Cheng, Yeo, Jayven Chee Chuan, Soh, Jia Wen Jaslin, Li, Peiyu, Tan, Swee Ching, Thitsartarn, Warintorn, and He, Chaobin
- Subjects
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PLASTICS , *ELECTRONIC equipment , *CELLULOSE , *THERMOPLASTICS , *MODERN society - Abstract
Modern human societies are highly dependent on plastic materials, however, the bulk of them are non‐renewable commodity plastics that cause pollution problems and consume large amounts of energy for their thermal processing activities. In this article, a sustainable cellulose hydroplastic material and its composites, that can be shaped repeatedly into various 2D/3D geometries using just water are introduced. In the wet state, their high flexibility and ductility make it conducive for the shaping to take place. In the ambient environment, the wet hydroplastic transits spontaneously into rigid materials with its intended shape in a short time of <30 min despite a thickness of hundreds of microns. They also possess humidity resistance and are structurally stable in highly humid environments. Given their excellent mechanical properties, geometry reprogrammability, bio‐based, and biodegradable nature, cellulose hydroplastic poses as a sustainable alternative to traditional plastic materials and even "green" thermoplastics. This article also demonstrates the possibility of 3D‐printing these hydroplastics and the potential of employing them in electronics applications. The demonstrated hydroshapable structural electronic components show capability in performing electronic functions, load‐bearing ability and geometry versatility, which are attractive features for lightweight, customizable and geometry‐unique electronic devices. [ABSTRACT FROM AUTHOR]
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- 2024
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19. DESIGN A SINGLE SCREW EXTRUDER FOR POLYMER-BASED TISSUE ENGINEERING.
- Author
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Naser, Mohamed A., Moeaz, Wael A., El-Wakad, Mohamed Tarek, and Abdo, Mohamed S.
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CHEMICAL engineering ,CHEMICAL processes ,ENGINEERING design ,ELECTRONIC equipment ,EXTRUSION process ,TISSUE scaffolds ,SCREWS ,NATURAL fibers ,PLASTIC extrusion - Published
- 2024
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20. Physical and Mechanical Properties and Durability Characteristics of New Pultruded GFRP Bars with Thermoplastic Resin.
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Ibrahim, Basil, Iraqy, Ahmed, Cousin, Patrice, and Benmokrane, Brahim
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DURABILITY ,VINYL ester resins ,FIBER-reinforced plastics ,SHEAR strength ,TRANSVERSE strength (Structural engineering) ,THERMOPLASTICS ,TENSILE strength - Abstract
This paper presents an experimental study that investigated the physical and mechanical properties as well as the tensile properties, transverse shear strength, and interlaminar shear strength of a newly developed glass fiber–reinforced polymer (GFRP) bar pultruded with a novel thermoplastic resin. The performance of the newly developed thermoplastic GFRP bar was compared with that of conventional thermoset-based GFRP bars pultruded with vinyl-ester resin to evaluate its suitability as internal reinforcement for concrete structures. Moreover, this study evaluated the durability characteristics of the newly developed thermoplastic GFRP bars under alkaline environmental conditions. The experimental results presented herein show that the performance of the newly developed thermoplastic GFRP bars tested exceeded that of the minimum mechanical properties specified in recent standards. Moreover, the new GFRP bars displayed high long-term durability performance. The findings of this study indicate the potential of the newly developed thermoplastic GFRP bars as a viable alternative to conventional reinforcement materials. Their favorable mechanical behavior supports their use in concrete structures, contributing to improved durability, sustainability, and overall performance. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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21. Crystallization kinetics analysis and modeling of aerospace PAEK materials.
- Author
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Ledesma, Rodolfo, Wohl, Christopher, and Grimsley, Brian
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ARTIFICIAL neural networks ,THERMOPLASTIC composites ,AEROSPACE materials ,COMPOSITE structures ,COMPOSITE materials ,CRYSTALLIZATION kinetics - Abstract
Polyaryletherketone (PAEK) thermoplastic composite materials have received increasing attention for the manufacturing of composite structures. One manufacturing process of great interest for PAEK composite structures is automated fiber placement, which can increase the throughput of complex part fabrication and reduce the use of autoclaves for assembly of composite parts. Understanding the thermal effects of the material allows the control and adjustment of manufacturing variables to assure the integrity of the composite structure. PAEK resins and carbon fiber reinforced composites have been analyzed using differential scanning calorimetry to study crystallization kinetics. Isothermal and non‐isothermal tests were conducted, and the time‐dependent crystallization kinetics were modeled using the Velisaris and Seferis model for isothermal processes and the Gaussian process regression method for non‐isothermal processes. The results show the influence of the thermal conditions and the chemical structures considering the ketone content, and the effects of the presence of the carbon fibers on crystallization kinetics. The models utilized describe with high accuracy the time‐dependent crystallization kinetics of PAEK composite materials. An artificial neural network application was also implemented using the non‐isothermal PAEK composite models for further prediction of relative volume crystallinity and crystallization rate. Highlights: Polyaryletherketone (PAEK) materials crystallize differently depending on the crystallization conditions.Carbon fibers influence the crystallization response in PAEK polymers.Machine learning was used to characterize crystallization kinetics.Activation energies were obtained for different thermal treatments.Artificial neural network tool was developed for PAEK composites in non‐isothermal regimes. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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22. A new effective phenomenological constitutive model for semi‐crystalline and amorphous polymers.
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Iadarola, Andrea, Ciardiello, Raffaele, and Paolino, Davide Salvatore
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STRAIN hardening ,STRAIN rate ,MECHANICAL models ,DEFORMATIONS (Mechanics) ,POLYMERS ,POLYETHERS ,POLYCARBONATES - Abstract
A new phenomenological constitutive model is proposed for the prediction of the tensile and compressive behavior of semi‐crystalline and amorphous polymers. The new model modifies the phenomenological model previously proposed by Zhou and Mallick (ZM model) to correctly predict the complex behavior of thermoplastic materials including the linear viscoelastic deformation, the non‐linear viscoelastic deformation, the yielding, the post‐yield strain softening and the post‐yield strain hardening. A validation activity based on literature data has been carried out for polyether‐ether‐ketone (PEEK) and polycarbonate (PC) materials. The new model proved effective in fitting with high accuracy all the phases of the flow stress behavior for the considered materials, across a wide range of strain rates and temperature conditions. Finally, the comparison with Zhu et al., Duan et al., Nasraoui et al., Mulliken‐Boyce and Zhou‐Mallick models showed the better fitting performance of the proposed phenomenological model. Highlights: Formulation of a new phenomenological model.Validation on mechanical test of semi‐crystalline and amorphous thermoplastics.Comparison with different phenomenological models present in the literature.Superior prediction results achieved compared to previously developed models. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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23. Optimized mechanical properties of carbon fiber reinforced thermoplastics by tuning polymer chain length based on quad‐screw extrusion.
- Author
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Choi, Woo Seong, Kim, Ki Hoon, and Kim, Seong Yun
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CARBON fibers , *THERMOPLASTICS , *POLYMERS , *FLEXURAL strength , *TENSILE strength , *MOLECULAR weights - Abstract
Highlights There is a need for cost‐effective manufacturing methods to optimize the impregnation and mechanical properties of carbon fiber reinforced thermoplastics (CFRTPs) by overcoming the low flowability of thermoplastics due to their high melt viscosity. In this study, to improve the impregnation of the CFRTP by inducing low melt viscosity, a strategy to control the molecular weight (MW) of thermoplastic polymer was developed. Through the quad‐screw extrusion (QSE) process, as the rotational speed of the QSE increased, the MW of the polypropylene (PP) matrix decreased, resulting in improved flowability and impregnation characteristics of the matrix, as well as enhanced mechanical strength of the CFRTP. The tensile and flexural strengths of the CFRTP were optimized at 1500 rpm, resulting in 77% and 23% improvements, respectively, compared to the CFRTP with raw PP. Therefore, the applied QSE process effectively controlled the MW, melt viscosity, and flowability of the PP matrix and produced CFRTP with improved mechanical strength. Mechanical degradation using QSE was applied to improve flowability of matrix. As polymer chain length decreased, impregnation between CF and matrix was improved. The improved impregnation characteristics resulted in the improved mechanical strengths. There is an optimal matrix MW to optimize the mechanical strengths of CFRTP. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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24. An Algorithm for Computing Entanglements in an Ensemble of Linear Polymers.
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Patel, Pramod Kumar and Basu, Sumit
- Subjects
- *
ALGORITHMS , *THERMOPLASTICS , *LINEAR polymers - Abstract
The entanglement length plays a key role in deciding many important properties of thermoplastics. A number of computational techniques exist for the determination of entanglement length. In Ahmad et al.,[1] a method is proposed that treats a macromolecular chain as a 1D open curve and identifies entanglements by computing the linking number between two such interacting curves. If the curves wind around each other, a topological entanglement is detected. However, the entanglement length that is measured in experiments is assumed to be between rheological entanglements, which are clusters of such topological entanglements that collectively anchor the interacting chains strongly. In this article, the method of clustering topological entanglements into rheological ones is further elaborated and the robustness of the method is assessed. It is shown that this method estimates an entanglement length that depends on the forcefield chosen and is reasonably constant for chain lengths longer than the entanglement length. For shorter chain lengths, the method returns an infinite value of entanglement length indicating that the sample is unentangled. Moreover, in spite of using a geometry‐based algorithm for clustering topological entanglements, the estimated entanglement length retains known empirical connections with physical attributes associated with the ensemble. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
25. Fluorinated graphite reinforced polytetrafluoroethylene/poly(butylene terephthalate) composites as friction materials for deep‐sea applications.
- Author
-
Su, Qiong, Wang, Zhongxu, Liu, Liang, Wang, Hongling, Wang, Jianzhang, Wang, Yanbin, Liu, Hao, and Yan, Fengyuan
- Subjects
FRICTION materials ,GRAPHITE fluorides ,OCEAN engineering ,COMPOSITE materials ,BUTENE ,POLYTEF ,POLYETHYLENE terephthalate - Abstract
The application of polymer composites is one of the most effective methods for preventing lubrication failure in deep‐sea engineering. In this study, fluorinated graphite (FGr) microsheets were incorporated into polytetrafluoroethylene (PTFE) microparticle‐filled poly(butylene terephthalate) (PBT) composites. The tribological performance in the simulated deep‐sea environment at elevated seawater pressure equivalent to 3000 m ocean depth was investigated. The results showed that FGr enhances the flexural and compressive strengths, thermal stability, and seawater resistance of the PTFE/PBT composite. The wear rate was decreased to 96% at the critical FGr content of 4% by improving the transfer onto the metallic counterfaces, preventing direct contact and shear between friction couples. Moreover, the seawater pressure impedes composite transfer, leading to a 29% increase in the wear rate. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
26. Effect of core–sheath bi‐polymeric scaffolds fabricated from acid‐soluble collagen and poly(lactic acid) derivatives on wound healing.
- Author
-
Mukta, Nasima Akter, Ahmed, Samina, Sarwaruddin Chowdhury, A. M., Tareq, Shafi M., Sajib, Abu Ashfaqur, Bashar, M. S., and Haque, Papia
- Subjects
LACTIC acid ,VINYL acetate ,FIELD emission electron microscopes ,WOUND healing ,LABORATORY rats ,COLLAGEN - Abstract
The core–sheath bi‐polymeric scaffold has been proven as an encouraging material based on the requirement of scaffolds. This study aims to prepare electrospun core–sheath scaffolds by using acid‐soluble collagen (ASC) as core material and poly(lactic acid) (PLA) or PLA‐g‐VAc as sheath material to get the most in combination from a hydrophilic and a hydrophobic polymer. ASC is extracted from waste Tilapia fish skin conserving the triple helix structure of the α1 (130 kDa) chain, and a α2 (120 kDa) chain cross‐linked with the β (280 kDa) chain confirmed by amino acid profile, sodium dodecyl sulphate‐polyacrylamide gel electrophoresis. PLA‐g‐VAc is prepared by grafting vinyl acetate (VAc) onto the PLA chain using benzoyl peroxide as the initiator. FT‐IR, 1H NMR, and 13C NMR of PLA‐g‐VAc reveal that grafting occurs between the double bond of VAc and the methine group of PLA. The morphology of the scaffolds is determined by the field emission scanning electron microscope. FT‐IR, thermogravimetric analysis, differential scanning calorimetry, XRD, and water contact angle measurements are used for further characterization of scaffolds. In vivo, cytotoxicity analysis on the Vero cell line exposes that scaffolds are biocompatible. Application of scaffolds to the surgically produced wounding of skin in a rat model followed by histological assay indicates the enhanced properties of core–sheath scaffolds rather than the single polymeric scaffolds. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
27. Identification of percolation threshold of spray‐dried cellulose nanocrystals in homopolymer polypropylene composites.
- Author
-
Wang, Xueqi, Wang, Pixiang, Liu, Shaoyang, Zhan, Ke, Via, Brian, Gallagher, Tom, Smidt, Mathew, Gardner, Douglas J., Elder, Thomas, and Peng, Yucheng
- Subjects
PERCOLATION ,MALEIC anhydride ,POLYPROPYLENE ,IMPACT strength ,FLEXURAL strength ,CELLULOSE nanocrystals - Abstract
Understanding the percolation threshold is essential for determining the performance of particle‐reinforced polymer composites. Spray‐dried cellulose nanocrystals (SDCNC) of micrometer size reinforced homopolymer polypropylene (HPP) composites at 20, 30, 40, and 50 wt.% were prepared to investigate the percolation threshold of SDCNC particles in HPP. The effect of a compatibilizer (maleic anhydride polypropylene (MAPP)) at 3, 5, and 7 wt.%, on the SDCNC percolation networks and composites performance were also studied. The results indicated that SDCNC particle percolation networks in HPP were established between 30 and40 wt.%. For composites without MAPP, the impact strength significantly increased by up to 23% below the percolation threshold and declined beyond it. The peak crystallization temperature of HPP was steadily increased until 30 wt.% SDCNC particles were added due to the SDCNC saturated nucleation function at the threshold. Introducing MAPP significantly improved tensile strength (58%), tensile strain (61%), flexural strength (45%), and impact strength (91%) compared with the corresponding composites without MAPP, attributed to the enhanced interfacial adhesion between the SDCNC particles and HPP. Water absorption results indicated that adding MAPP changed the SDCNC particle distribution networks within the matrix above the percolation threshold but did not change it below the threshold. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
28. An Algorithm for Modeling Thermoplastic Spherulite Growth Using Crystallization Kinetics.
- Author
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Husseini, Jamal F., Pineda, Evan J., and Stapleton, Scott E.
- Subjects
- *
POLYETHER ether ketone , *OPTIMIZATION algorithms , *HOMOGENEOUS nucleation , *DIFFERENTIAL scanning calorimetry , *HETEROGENOUS nucleation - Abstract
Crystallization kinetics were used to develop a spherulite growth model, which can determine local crystalline distributions through an optimization algorithm. Kinetics were used to simulate spherulite homogeneous nucleation, growth, and heterogeneous nucleation in a domain discretized into voxels. From this, an overall crystallinity was found, and an algorithm was used to find crystallinities of individual spherulites based on volume. Then, local crystallinities within the spherulites were found based on distance relative to the nucleus. Results show validation of this model to differential scanning calorimetry data for polyether ether ketone at different cooldown rates, and to experimental microscopic images of spherulite morphologies. Application of this model to various cooldown rates and the effect on crystalline distributions are also shown. This model serves as a tool for predicting the resulting semi-crystalline microstructures of polymers for different manufacturing methods. These can then be directly converted into a multiscale thermomechanical model. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
29. Synthesis and alkaline hydrolytic degradation of isosorbide‐based polycarbonates via incorporation of ethoxylated isosorbide as a comonomer.
- Author
-
Lee, Hak Yong, Myung, Suwan, Lee, Won‐Ki, and Lee, Jae‐Chang
- Subjects
POLYCARBONATES ,BISPHENOL A ,CONTACT angle ,VISIBLE spectra ,TENSILE strength ,MOLECULAR weights - Abstract
Synthesis of polycarbonates (PCs) from isosorbide (ISB) monomers has been recently investigated. However, compared to bisphenol A, PCs face challenges in commercialization because their high rigidity renders it difficult to increase their molecular weight, resulting in high brittleness. To address these limitations, a flexible co‐monomer, ethoxylated ISB (EI5), was mixed with ISB to produce ISB/EI5‐based PCs. The structures of the ISB/EI5‐based PCs were controlled by varying the ISB/EI5 ratio from 100/0 to 60/40 mol%. Films were fabricated, and their thermal, optical, and mechanical properties and degradability were investigated. With increasing EI5 content, the thermal processability of the ISB/EI5‐based PCs improved, and the produced films exhibited excellent visible light transmittance and UV‐blocking effects. The mechanical properties of the ISB/EI5‐based PCs indicated sufficient tensile strength (σ = 89.7–72.9 MPa), competitive to that of commercial PC, and the properties could be controlled by adjusting the ISB/EI5 ratio. The contact angle and hydrolysis behavior of the ISB/EI5‐based PC films indicated increased surface hydrophilicity and increased degradation rate with increasing EI5 content. In conclusion, the structural control of the ISB/EI5‐based PCs enhanced their moldability and degradability, suggesting their potential commercial utilization. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
30. 4D printable shape memory polyurethane with quadruple hydrogen bonding assembly.
- Author
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Xu, Yuanyang, Wang, Yanjun, Wei, Hongxiu, Dai, Tiancheng, Li, Zhen, Li, Jiehua, Luo, Feng, and Tan, Hong
- Subjects
SHAPE memory effect ,POLYURETHANES ,HYDROGEN bonding ,THERMOPLASTICS ,FABRICATION (Manufacturing) - Abstract
Four‐dimensional (4D) printing is an emerging technology for fabricating customizable tissue engineering implants. 4D printed implants with shape memory properties are expected to provide new application opportunities for minimally invasive surgery. A great challenge is to prepare the biodegradable materials with robust mechanical properties for 4D printing ink. Herein, biodegradable thermoplastic polyurethanes (TPUs) based on IPDI, PEG, PCL, and diols with UPy motifs are synthesized. The pendant UPy motifs can dimerize to form physical crosslinking by quadruple hydrogen bonding assembly, accompanying with significant improving the mechanical properties, self‐healing capability and shape memory effect. With an optimal UPy content, the PU‐U2‐25% shows robust mechanical properties and much better shape memory effect compared with the PU‐U2‐0% without UPy. Moreover, the TPUs show a facile processing at relative low temperature approximately 100 °C which avoid degradation at high processing temperature. Combined with the good processability, self‐healing capacity and shape memory effect of the PU‐U2‐25%, we primary demonstrated its 4D printing potential for various specimens. This work proposed a new strategy to design TPUs integrating the merits of linear and pendant physical crosslinking motifs to obtained excellent comprehensive properties, which would develop the 4D printable materials for applications of personalized and minimally invasive treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. In‐situ polymerizable thermoplastic and bio‐epoxy based composites for offshore renewable energy applications.
- Author
-
Bhatia, Gursahib Singh, Hejjaji, Akshay, Pothnis, Jayaram R., Portela, Alexandre, and Comer, Anthony J.
- Subjects
- *
THERMOSETTING composites , *RENEWABLE energy sources , *THERMOPLASTICS , *THERMOPLASTIC composites , *FIBER-matrix interfaces , *TIDAL power , *EPOXY coatings - Abstract
Highlights This study evaluates various quasi‐static mechanical properties of an in‐situ polymerizable thermoplastic and a bio‐based thermosetting composite comprising of non‐crimp fabric reinforcement for potential use in the next generation of Offshore Wind and Tidal Power platforms. Mechanical properties are characterized under tensile, flexural, in‐plane shear and interlaminar shear loading. Results reveal that the evaluated properties differ based upon matrix type. Fractographic evidence from scanning electron microscopy is used to explain the differences observed and was generally consistent in terms of revealing cohesive failure at the fiber‐matrix interface for the thermoplastic composite and contrasting adhesive failure for the thermosetting composite. For glass fiber reinforcement, the thermoplastic composite is superior in terms of flexural 90° properties (+20%) while the thermosetting composite performed better in flexure 0° in terms of both strength (+15%) and modulus (+25%). In terms of interlaminar shear, the thermosetting composite exhibited higher strength (+14%) while Tensile and in‐plane shear properties are similar for composites of both resin systems. Overall, neither composite is superior in terms of overall mechanical properties and both matrices show promise as a stepping stone towards the use of more sustainable constituents in offshore structures. Quasi‐static mechanical performance and failure analysis of relatively sustainable composites are presented. Failure analysis indicate cohesive failure of the thermoplastic based composite and interfacial failure of the thermosetting based composite. Proposed composites are benchmarked against the composites manufactured using conventional resins. Overall, both matrices show promise as a stepping stone towards more sustainable offshore structures. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. Real‐time dielectric monitoring of isothermal polymerization of methyl cyanoacetate and diethylene glycol dimethacrylate.
- Author
-
Yang, Haoran, Liu, Fengquan, Zhao, Kongshuang, Zhou, Jianjun, and Li, Lin
- Subjects
DIETHYLENE glycol ,ISOTHERMAL processes ,DIELECTRICS ,POLYELECTROLYTES ,ADDITION polymerization ,POLYMERIZATION - Abstract
Dielectric spectroscopy (DS) was employed to monitor the isothermal polymerization processes of P(MCA‐DEGDMA) formed by the alternating copolymerization of methyl cyanoacetate (MCA) and diethylene glycol dimethacrylate (DEGDMA) at different temperatures in real time. P(MCA‐DEGDMA) is a polyether containing functional groups (O, CN, COOCH3) which can promote the transport of ions Li+, thereby having the potential to apply in polymer electrolytes. It is beneficial to investigate the effect of temperature and time on P(MCA‐DEGDMA) polymerization and choose a suitable synthesis strategy through dielectric monitoring. A time‐ and temperature‐dependent relaxation process induced by orientational polarization of the P(MCA‐DEGDMA) chain was observed over a frequency range from 10 kHz to 4 × 106 Hz. The time to reach polymerization equilibrium (tequ) and the dielectric conversion were determined through the time variations of the conductivity at low frequency (κl). The polymerization process shows the characteristic of "fast followed by slow," and the tequ can be advanced by raising the polymerization temperature. In addition, by discussing the monitoring time dependence of relaxation time (τ) and permittivity (ε), it was concluded that the extent of polymerization (α) for P(MCA‐DEGDMA) at 40°C is the largest, and the optimal polymerization temperature is between 30 and 50°C. Furthermore, the free activation energy (ΔG), activation enthalpy (ΔH), and activation entropy (ΔS) of the relaxation process caused by the motion of the P(MCA‐DEGDMA) chain in three temperature ranges (10–20°C, 30–40°C, 50–60°C) were calculated by using Eyring's equation, from which the physical image of various structures and conformations of the P(MCA‐DEGDMA) chain during monitoring was proposed. Considering the effect of temperature on the generation and migration of free ions, and on the structure and conformation of the P(MCA‐DEGDMA) chain, some suggestions for the synthesis of P(MCA‐DEGDMA) are given: during the polymerization, the temperature is controlled at 10°C in the early stage and then gradually raised to 40°C, which may be beneficial to improving the extent of polymerization of P(MCA‐DEGDMA). Our work may be helpful to investigate the polymerization process of polyether obeying the same synthesis mechanism with P(MCA‐DEGDMA). It can be proven that DS is useful in detecting the inner information of the system changing over time through our work. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
33. Effect of polyphenylene sulfide sulfone sizing agent on interfacial, thermal, and mechanical properties of carbon fiber.
- Author
-
Yifan Zhuang, Haibin Liu, Shaoyang Zhou, Zhehao Jia, and Ying Sun
- Subjects
POLYPHENYLENE sulfide ,CARBON fibers ,GLASS transition temperature ,SULFONES ,HEAT treatment ,SURFACE energy ,THERMAL stability - Abstract
Polyphenylene sulfide sulfone (PPSS) was synthesized by one-step method and utilized as a sizing agent for carbon fibers. The effects of various monomer ratios, reaction time, and reaction temperature were investigated on the molecular weight of PPSS. The thermal analysis revealed that the product PPSS exhibited a glass transition temperature exceeding 215.5°C, indicating exceptional thermal stability. After PPSS sizing treatment, the grooves on the surface of carbon fibers were filled, resulting in a substantial enhancement of the micro interface properties. The surface energy was increased by 8.2%, while the maximum weight loss temperature was 27.8% higher than that of the commercial carbon fiber. The tensile strength of the carbon fiber after heat treatment reached 2196 MPa, representing a 45.9% increase over that of the commercial carbon fiber. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
34. Preparation of agar-silica nanofilms through melt mixing: Extending beef shelf life through biodegradable packaging.
- Author
-
Untoro, Yovilianda Maulitiva, Nurhamiyah, Yeyen, Firdiana, Bonita, Nissa, Rossy Choerun, Syamani, Firda Aulya, Fateha, Fateha, Fransiska, Dina, Dawam Abdullah, Akbar Hanif, and Arcana, I. Made
- Subjects
NANOFILMS ,VAPOR barriers ,PACKAGING film ,CHEMICAL properties ,SILICA nanoparticles ,EDIBLE coatings - Abstract
The current study used the melt mixing approach to create a variety of agar/SiO
2 nanoparticle (AG/Si) nanocomposites films. Silica nanoparticles were included as a filler in different proportions, varying from 0% to 5% (w/w). The study examined how the composition impacted the chemical properties, mechanical characteristics, thermal properties, water vapor barrier, surface color, and antimicrobial capabilities. After the addition of SiO2 , the tensile strength increased significantly from 30.77 to 40.97 MPa at 4% SiO2 . Moreover, the presence of SiO2 was improved the contact angle from 53.81° to 63.24°, brightness of the film (L*) from 70.63 ± 3.34 up to 84.80 ± 2.26, maximum degradation temperature (Tdmax ) from 315 to 317°C and melting temperature (Tm) from 109 to 125°C. In the meantime, following the integration of SiO2 content, the density of agar film dropped from 1.27 to 1.16 kg/m³. The AG/Si film effectively prevented bacterial growth and extended the shelf life of fresh beef, suggesting a novel biobased option for antimicrobial packaging film. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
35. Weld-line strength prediction for glass fiber reinforced polyamide-6 material through integrative simulation and its experimental validation.
- Author
-
Jadhav, Ganesh and Gaval, Vivek
- Subjects
- *
PLASTICS , *INHOMOGENEOUS materials , *FIBER orientation , *PRODUCTION methods , *STRUCTURAL models , *INJECTION molding - Abstract
Injection molding is one of the preliminary production methods for plastic components. Typically, injection molding Moldflow simulations predicts potential issues like air void, weld-line, warpage etc. This work focuses on weld-line defect, which occurs when two or more flow fronts are meets each other during filling of the cavity. Most of the commercial algorithms are based on isotropic and homogeneous material assumptions however plastic materials are anisotropic and heterogeneous in nature. Therefore, accuracy with isotropic solvers may vary with actual reality. To consider material anisotropy and heterogeneous nature of the material, an integrative simulation is advantageous technology which gives more realistic results. A unique approach of integrative simulations has been used in this work to predict the strength of the weld-line as there is no direct standard procedure or software available to get weld-line strength. Moldflow simulation is performed on specially designed plaque wherein the weld-line is reproduced considering 30% glass-filled polyamide-6 material. The new material model is developed by mapping the structural model of tensile specimens on the Moldflow simulated plaque with integrative mapping approach. The mapped model considers fiber orientation and weld-line characteristics of the material which is then solved in the Abaqus structural solver. Experimental validation is performed by manufacturing of weld-line plaques, specimen preparation, and experimental testing. The results correlation is done for an isotropic and anisotropic material model with experimental results. The correlation study shows, a significant difference in results for isotropic simulation and integrative anisotropic simulations. The failure pattern and load-displacement behavior of integrative simulation is close match with experimental results with minimum 93% accuracy. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. Hybrid multi-scale modeling of fused deposition modelling printed thermoplastics: An introduction to material degradation parameter.
- Author
-
Shah, Adarsh Kumar and Jain, Atul
- Subjects
- *
FUSED deposition modeling , *MULTISCALE modeling , *THERMOPLASTICS , *POLYLACTIC acid , *SCANNING electron microscopes - Abstract
With the increasing popularity of fused deposition modelling (FDM), an improved understanding of the interdependence between process-structure-property (P-S-P) of FDM manufactured (FDMed) parts is imperative. This paper proposes models for linking the microstructure and degradation of properties during the FDM process with the mechanical properties. Through careful and elaborate finite element (FE) modeling, it is demonstrated that there is definite material degradation during the FDM process, which cannot be attributed only to extra voids generated during printing. A novel hybrid multiscale model is proposed to estimate the degradation parameter and utilize this information to predict the printed coupons' properties. Additionally, two methods for generating representative volume element (RVE) are demonstrated using scanning electron microscope (SEM) imaging and density data. For the experimental validation, polyamide (PA) and polylactic acid (PLA) filaments and dogbone samples with multiple raster orientations were tested. The use of degradation parameter during modeling leads to very accurate results for both PLA and PA. Also, it presents insights into the limitations of the FDM process and possible improvements. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
37. Recycling of Thermoplastic Glass Fiber‐Reinforced Composites Using High‐Voltage Fragmentation.
- Author
-
Schmidt, Jannick, Auer, Maximilian, Grammel, Lena, and Woidasky, Jörg
- Subjects
- *
GLASS-reinforced plastics , *GLASS recycling , *GLASS fibers , *THERMOPLASTICS , *CORE materials , *REINFORCED thermoplastics , *WASTE recycling - Abstract
A rectangular polymer profile made of glass fiber‐reinforced thermoplastic sheathing material and a polyethylene terephthalate foam core were to be separated for recycling. For this purpose, a mechanical recycling process utilizing a cutting mill and the high‐voltage fragmentation (HVF) process were used and their achievements in composite separation were compared. For both separation methods, parameter variations resulted in a total of two test series each consisting of drying, screening, optional density separation, ashing, weighing, microscopic analyses, and glass fiber length measurements. Using HVF, a better separation of the core and sheath materials was achieved and longer glass fibers could be recovered. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
38. Investigation of Thermal Fatigue Behavior for HDPE Composites Reinforced by Nano Alumina.
- Author
-
Abdullah, Orhan Sabah and Mahdi, Akeel Zeki
- Subjects
HIGH density polyethylene ,THERMAL fatigue of metals ,THERMOPLASTICS ,MECHANICAL behavior of materials ,HEAT resistant materials - Abstract
High-Density Polyethylene (HDPE) like other thermoplastics has low mechanical properties which limits its range of applications, especially under the influence of dynamic loads and high temperatures. Therefore, as one of the highly attractive approaches for improving mechanical properties, nanomaterials have been used as reinforcement materials in polymer matrix composite. The present study focuses on the role of nanomaterials on the mechanical properties and fatigue resistance of high-density polyethylene reinforced with (1, 2, and 3%) nano alumina oxide at a range of testing temperatures between 20 and 60ºC. The results manifested that the addition of nano alumina oxide improves the strength of base polyethylene and increases the fatigue resistance by (63.7%, 146.5%, and 228.4%), (69.25, 163.5 and 202.8) and (94%, 214.8% and 290.3) at (20. 40 and 60°C), respectively in cooperation with the pure high-density polyethylene. In addition, as the applied testing temperature increases, the fatigue resistance in all test specimens decreases. It was found that the highest fatigue resistance occurred at (HDPE+3%Al2O3) composite due to the good distribution of nano Al2O3 within the HDPE base which led to a better crack propagation prevention than other composites. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Biopolymer nanocomposite blends of poly(lactic acid) and polyhydroxybutyrate biopolymers reinforced with cellulose nanofibrils at low loading ratio.
- Author
-
Aydemir, Deniz, Gumus, Havva, Altuntas, Ertugrul, Yalçın, Ömer Ümit, and Özan, Zeynep Eda
- Subjects
LACTIC acid ,RHEOLOGY ,DIFFERENTIAL scanning calorimetry ,SCANNING electron microscopy ,BIOPOLYMERS - Abstract
This study investigated the mechanical, morphological, thermal, rheological properties, and accelerated aging performance of poly(lactic acid) (PLA)/polyhydroxybutyrate (PHB) blends with cellulose nanofibrils (CNFs) at low loading ratio. According to the obtained results, the addition of both PLA and CNFs were found to generally increase the mechanical properties of the biopolymer nanocomposites (BNCs). Morphological characterization with scanning electron microscopy (SEM) exhibited that cellular structure occurred in all the BNCs with adding both PLA and CNFs. Thermal stability of the BNCs improved with PLA and CNFs. The addition of CNFs and PLA generally increased the isotherms including Tg, Tc, and Tm according to differential scanning calorimetry (DSC), and it was found that the blends' crystallinity dropped because of a poor crystallinity of PLA. The addition of both PLA and CNFs provided an improvement on the rheological and viscoelastic properties of the neat PHB. XRD pattern of all the BNCs was found to be similar to the neat blends and the BNCs. In the accelerated weathering test, the adding PLA to neat PHB was found to provide more improvement than adding of CNFs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Thermoplastic polyimide with good comprehensive performance based on carbazole groups and short flexible linkages.
- Author
-
Du, Qi‐Yuan, Chen, Wei‐Peng, Guo, Hao, Wang, Zhi, Zhao, Li, Zhu, Yongxiang, Tan, Wan‐Yi, Min, Yonggang, and Liu, Yidong
- Subjects
POLYIMIDES ,THERMOPLASTICS ,CARBAZOLE ,ELECTRONIC packaging ,MECHANICAL behavior of materials ,THERMAL expansion - Abstract
Thermoplastic polyimides (TPIs) can meet the requirements of advanced electronic packaging such as flexible copper clad laminate (FCCL) applied under extreme conditions, attributed to their excellent thermal stability, mechanical properties, electrical insulation and chemical resistance. With the increasing demands for electronic devices, such as applications in high‐frequency communication, it is highly desirable to develop high‐performance TPI with good thermoplasticity, thermal stability, mechanical properties and dielectric properties. However, there is a trade‐off between thermoplasticity and other properties. Herein, we introduce an effective strategy to afford TPIs with good performance by copolymerization of a diamine monomer consisted of a coplanar aromatic carbazole group and a short flexible linkage methylene group. On the one hand, short flexible linkages help improve the flexibility of polymer chains and are not too much to enable small‐scale molecular motions below Tg. On the other hand, coplanar aromatic donor groups benefit to strong charge transfer complex (CTC) interaction and π‐π stacking interaction. Based on this strategy, the resultant TPI possesses good thermoplasticity with a proper Tg of 348 °C. Meanwhile, it preserves a low coefficient thermal expansion of 48 ppm K−1, low dielectric constant/dielectric loss factor of 3.27/0.0073 at 10 GHz, and tensile strength of ca. 78 MPa. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
41. Quantifying the cooperative evolution of microphase segregation and nanostructural order in annealed polyurethanes of MDI‐BDO‐PTHF.
- Author
-
Terban, Maxwell W., Pöselt, Elmar, Malfois, Marc, Schulz, Armin, Schander, Edgar, Abeykoon, A. M. Milinda, Hinrichsen, Bernd, and Dinnebier, Robert E.
- Subjects
POLYURETHANES ,CRYSTAL structure ,ANNEALING of metals ,MECHANICAL behavior of materials ,THERMOPLASTICS - Abstract
Here, we quantify the relationship between microphase segregation and local structure development in thermoplastic polyurethanes. Samples were prepared with varying ratios of 4,4′‐methylene diphenyl diisocyanate (MDI) and 1,4‐butanediol (BDO) to polytetrahydrofuran (PTHF) and annealed at temperatures Ta between RT–140 °C for 20 h each. Distinct populations of smaller and larger ordered domains are distinguished by pair distribution function analysis. The intermediate‐range order of nanoscale hard domains in the paracrystalline state (form I) is directly extracted and characterized. The results suggest that form I of the MDI‐BDO:PTHF system presents a conformational and packing order similar to the form III structure, typically obtained from stretching/annealing, but with limited spatial coherence of 3–7 nm. Heating above Tg of the hard segments is necessary to achieve a substantial structural response from the annealing treatment. Increasing Ta promotes purification of the soft phase via microphase segregation, coalescence of the hard blocks, and growth of paracrystalline phase, while a minority fraction of longer‐range ordered domains left over from production remains relatively constant. We observe a composition‐dependent decrease in the average nearest‐neighbor distance that can be correlated with the greater number of CC, CN, and CO bonds with increased hard segment content. A non‐linear deviation in the trend is observed to correlate with sample densification. The mechanical and thermal behavior of the samples is intimately tied to the segregation state. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
42. Direct injection molding of recycled thermoplastics using a two-stage process including melt filtration and degassing.
- Author
-
Köpplmayr, Thomas, Fellner, Klaus, Fehringer, Stefan, Klammer, Günther, Traxler, Ines, Czaker, Sandra, and Fischer, Jörg
- Subjects
- *
INJECTION molding , *THERMOPLASTICS , *CIRCULAR economy , *MELT spinning , *FREE surfaces , *PELLETIZING , *ODORS - Abstract
Mechanical recycling is an essential tool in transitioning the plastics industry to a circular economy. The traditional route requires pelletizing after extrusion with melt filtration and degassing of the material. These (re)granulated materials can be later processed via injection molding. We present a study of a machine concept, which can be used to directly convert grinded or agglomerated thermoplastic materials to injection-molded products using a two-stage process. The machine concept consists of an extruder, a melt filter and an injection unit. To reduce odor and volatile organic contaminations, which are often present in post-consumer and sometimes also in post-industrial waste, a degassing system is introduced for the injection unit. Our study covers (i) virgin polypropylene with a humidity carrier and varying amount of water, (ii) grinded polyethylene from post-consumer caps, (iii) polypropylene agglomerate from post-consumer sheets, (iv) pre-sorted polypropylene flakes from post-consumer waste and (v) commercially available pellets from post-consumer PE/PP mixtures. Process stability and plasticizing performance is investigated under different boundary conditions. Effective degassing is achieved by increasing the free surface of the melt in the first section of the injection screw. Voids and closed pores are further reduced if vacuum is used. Mechanical testing shows an increasing tensile modulus of the injection-molded parts due to the reduction of volatile contaminations. The comparison to a state-of-the-art compounding process shows similar results. The machine concept represents an advanced opportunity to increase the content of recycled thermoplastics in injection molding including melt filtration and degassing, which would be very limited in a standard injection molding process. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
43. Development of scale-up rules for the quasi-simultaneous laser transmission welding (LTW) of thermoplastics.
- Author
-
Arndt, Theresa and Schöppner, Volker
- Subjects
- *
LASER welding , *JOINING processes , *THERMOPLASTICS , *WELDING , *MANUFACTURING processes - Abstract
Due to the steadily growing demand for plastic components, the demand for the respective joining processes is also increasing. More and more components of various types are being substituted by plastic ones. As a result, the demands made on the corresponding joining processes are also rising. The reduction of costs and time is the decisive factor for the use of new joining processes. Particularly in the case of plastic welding processes, not only high bond strength but also optical quality is a key issue. This includes laser transmission welding. One advantage of this process is the production of particle-free weld seams that meet optical requirements. In order to simplify this joining process and thus increase its use, scale-up rules are needed that allow process parameters for different component geometries to be determined in the shortest possible time without having to determine them experimentally. Here, the process parameters for new component geometries are to be calculated using existing welding processes. This can lead to enormous time and cost reductions and thus simplify and at the same time increase the use of laser transmission welding. Within the scope of this research project, a scale-up exponent was determined for two material combinations, which enables calculation of the process parameters and at the same time ensures consistent weld seam quality. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
44. Experimental and simulative investigation of 2C injection molding of thermoplastics with low HDT and LSR using dynamic temperature control.
- Author
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Nikousaleh, Mohammad Ali, Hartung, Michael, Giesen, Ralf-Urs, and Heim, Hans-Peter
- Subjects
- *
INJECTION molding , *TEMPERATURE control , *THERMOPLASTICS , *MOLD control , *MEDICAL technology , *PRICES , *RAYLEIGH number - Abstract
Most injection-molded thermoplastic/LSR composite parts are made of PBT or PA as hard components. This is due to the high heat deflection temperature of these materials. These hard components are usually inserted into the LSR cavity, which is heated to over 140°C to cure the LSR, during the overmolding process. Accordingly, the thermoplastic's heat deflection temperature must be higher than the selected mold temperature for LSR to ensure that the thermoplastic does not soften and deform. Medical technology usually relies on standard thermoplastics like ABS or PE because of the material price. It is especially expensive when the assembly is needed when adding silicone components to functional elements such as valves. The dynamic temperature control in the mold gives the opportunity to use standard thermoplastic in two shot injection molding. This technology allows, switching the mold temperature back and forth in a few seconds (for example, 80°C and 180°C). As a result, LSR can be vulcanized and thermoplastics can be safely de-molded. For this process, one of the problems is heating the LSR from one side, which results in a prolongation of curing time and could even cause the non-curing of LSR in some parts. Hopefully, here simulation can show how the required temperature comes in the best way to the LSR. This study investigates the effects of different process temperatures and heating times of the curing degree and the adhesion between two components. In addition to the experimental work, the results of simulations using the virtual molding software SIGMASOFT® have been provided to determine the curing degree and the temperature of different positions of the mold. In conclusion, Process data of simulation and standard process data were evaluated and compared in experiments using the results of peeling tests according to VDI 2019. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
45. The effect of Aceh Gayo coffee consumption on colour stability in thermoplastic nylon dental base.
- Author
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Atmaja, Widyapramana Dwi and Gondomono, Annindy Regitasoelyh
- Subjects
- *
DENTAL materials , *NYLON , *COFFEE , *COLOR , *COFFEE beans , *DENTURES , *THERMOPLASTICS , *THERMOPLASTIC composites - Abstract
The denture base is one of the components of the denture, which is used as a place for denture attachment, which can restore the facial contour of the user so that it looks aesthetically pleasing. Thermoplastic nylon is one of the most widely chosen and developed polymer denture base materials in dentistry because it has regular, tight, strong inter-chain bonds, is insoluble in solvents, is resistant to heat, and has high tensile strength due to its high tensile properties. The nature of thermoplastic nylon, which easily absorbs water, is feared to cause discoloration of the denture base due to the compound content in the liquid of Gayo Aceh Arabica coffee. This study was to determine the effect of Gayo Aceh coffee consumption on color stability on a denture base made of thermoplastic nylon. Type of research is an experimental laboratory with a pre-post-test design. The research samples were 8 which were printed in the form of discs with a diameter of 20 mm and a thickness of 2 mm, with a total sample of 4 samples per group. Group A was treated to soak in a solution of gayo aceh arabica coffee for 7 days, and group AR was treated to soak it in aquades solution for 7 days. Then, the sample was measured for changes in colour stability using spectrophotometry with the brand Shimadzu UV-2401, andthe results were tested for Shapiro-wilk normality, One Way ANOVA, and paired t-test. The results of the Shapiro-wilk normality test stated that the pre-test and post-test scores had a significant value (p>0.05). The result of OneWay Anova test showed p values = 0.770 and 0.121, which means that the variance of the pre-test and post-test group data is homogeneous. The results of the paired t-test analysis stated that the significant value was p = 0.038. There is an effect of Gayo Aceh coffee consumption on the colour stability of the denture base made of thermoplastic nylon. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
46. Validation of a multi-scale simulation for precise warpage prediction of injection molded semi-crystalline parts.
- Author
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Alms, Jonathan, Kahve, Cemi, Laschet, Gottfried, Çelik, Hakan, Mentges, Noah, and Hopmann, Christan
- Subjects
- *
INJECTION molding , *BENDING moment , *FORECASTING , *SOLIDIFICATION , *THERMOPLASTICS - Abstract
The simulation of the injection molding process of semi-crystalline thermoplastics is widely used and commercially available. Typical use cases for process simulations are melt flow optimization, tool design and finding process parameter sets for the production. In recent years, injection molding simulations also provide the prediction of shrinkage and warpage. These simulations, however, neglect the variations in local mechanical properties caused by inhomogeneous solidification and the resulting locally different spherulites microstructure. In order to account for the locally inhomogeneous solidification and the resulting local microstructure, and hence to improve the precision of the warpage prediction, a multi-scale simulation chain is developed and presented here. The multi-scale simulation chain predicts the shrinkage on the part scale taking into account the mechanical property distribution, which is derived based on the local microstructure using a two-stage numerical homogenization scheme. The numerical homogenization is able to consider the local degree of crystallization, which is noticeable reduced in the surface layers of the component, resulting in a reduction of the mechanical properties. To show the applicability of the multi-scale simulation chain, an experimental validation is presented using injection molded plates with thickness steps. The final warpage is measured using a tactile measurement (Zeiss O-Inspect 442). The bending moment caused by warpage and relative magnitude are compared with the numerical results. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
47. Warpage prediction for unidirectional reinforced thermoplastic extruded profiles.
- Author
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Lippens, Willem, Ivens, Jan, and Desplentere, Frederik
- Subjects
- *
SPECIFIC heat capacity , *RESIDUAL stresses , *THERMAL conductivity , *THERMAL properties , *FINITE element method , *YARN , *THERMOPLASTICS - Abstract
Thermoplastic over-extrusion is a continuous production process in which reinforcing UD-fibers are preheated and guided at constant line speed into an extrusion die. Here the fibers are surrounded by molten polymer. After the extrusion die, the composite is cooled by a combination of calibration units and water baths. At the end of the process line, the parts are cut to length. Products made with this process have a (or multiple) reinforced zone(s) in their cross-section, allowing for improved mechanical performance with a minimum of reinforcing materials when strategically located. However, due to the mismatch in coefficient of thermal expansion between the reinforcing fibers and the surrounding polymer, excessive warpage and residual stresses after cooldown are often present in the final products. Reducing these unwanted effects is currently done by a costly and lengthy trial-and-error approach. This study presents a multiphysics (thermal-structural) simulation laying the basis to predict warpage and residual stresses in an over-extruded product with complex cross-section using UD-GF/PET commingled yarns over-extruded with rigid PVC. It makes use of experimentally determined temperature-dependent mechanical properties as well as temperature-dependent thermal properties (specific heat capacity, thermal conductivity). The finite element model is compared to experimental data in order to check the validity. The thermal simulation has a maximum deviation of less than 15% when compared to experimentally determined temperatures. A strong overestimation is observed regarding the warpage prediction when compared to experimental data, which has been attributed to the simulated bonding conditions between the components. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
48. Development of an asymmetric torque model for the two screws of a twin screw extruder.
- Author
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Austermeier, Laura, Schöppner, Volker, and Alsoud, Abdallah
- Subjects
- *
SCREWS , *TORQUE , *ZONE melting , *THERMOPLASTICS , *TORSION - Abstract
In order to modify a polymer with additives or fibers in a way that is suitable for processing, corotating twin-screw extruders are generally used. An important factor in the melting of the plastic, which is necessary to homogeneously incorporate other components, is the energy input. Thermoplastics soften before they liquefy and finally, when subjected to excessive stress, are damaged and eventually decompose. A targeted energy input in the melting zone, which is sufficient to plasticize the material without damaging it, is therefore desirable. But apart from that, other zones like mixing zones should not be neglected. The underfed condition in which twin-screw extruders are usually operated results from the metering of the components, as well as the different flight pitches of the screw elements, which are used to build up and down for different process steps. In the extruder, a partial filling of the chambers with plastic melt occurs, which simplifies, for example, the degassing of the melt. Due to the same direction of rotation of the two screws, there might be a different distribution of the total melt or granules to the two screws and a different energy input. The present approach to determining the local torque input is based on the assumption that a resistance is created by the plastic, which torsions the screws. This torsion can be calculated to the required torque and thus the energy input can be determined. The higher the filling level of the screws, the higher the resistance and thus the higher the energy input. In order to show the influence of the degree of filling of the screws on the energy input in the extruder, investigations were carried out on a twin-screw extruder in which different partial fillings were provoked and the applied screw torque was measured. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. The Non-Crystalline State
- Author
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Ubic, Rick and Ubic, Rick
- Published
- 2024
- Full Text
- View/download PDF
50. Overview of Plastics, Usage, Pollution and Mitigation
- Author
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Sen, Gautam, Goel, Malti, editor, and Tripathi, Neha G., editor
- Published
- 2024
- Full Text
- View/download PDF
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