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Polypropylene (PP) is one of the most used polymeric materials worldwide, either as a neat material or as a matrix for composite manufacture employing a molding process. Fused deposition modeling (FDM) 3D printing is an alternative process that offers the potential for manufacturing value‐added products from PP. However, using neat PP for FDM is challenging because 3D‐printed PP warps and shrinks when cooled, and the mechanical properties of PP are poor. PP‐based composites with different fillers (e.g., glass, carbon, and natural fibers) have shown improved properties using FDM processes. An alternative filler for 3D‐printed PP‐based composites is basalt fiber (BF). The objective of this work was to assess the potential and impacts of BF as a filler for BF‐PP composites using FDM processes. PP was compounded with 15, 25, 35, and 45 wt% BF to produce filaments for 3D printing without adding any compatibilizer. Results of rheology studies, morphology, and mechanical and thermal properties of the 3D printed specimens showed that BF positively impacts Young's modulus (E), thermal stability, and dimensional stability of the composite. All composites, when processed at high shear rates (i.e., above 100 1/s), show approximately similar rheological behavior. E is almost doubled in the composite with 25 wt% BF and increased fourfold in the composite with 35 and 45 wt% BF, compared to neat PP. The Izod impact resistance of the formulations containing 35 and 45 wt% BF is ~70% that of neat PP. BF process easily and adequately reinforces PP composites manufactured via FDM. Highlights: Neat PP's poor mechanical properties are improved by adding basalt fiber (BF).Up to 45 wt% BF was used to reinforce PP‐based composites.PP‐BF composites are easier to process via DFM compared to neat PP.BF improves PP‐based composite's thermal and dimensional stability. [ABSTRACT FROM AUTHOR]

Manufacturing plastic parts with secondary feedstocks has risen to the forefront of importance in recent years. However, the variation in molecular weight and rheology of secondary feedstock can lead to inconsistent part quality. This work evaluates the effectiveness of a novel closed‐loop adaptive process control system that adjusts nozzle pressure in response to in‐mold pressure data. Five different recycled polypropylene blends, with a broad distribution of flow properties, were evaluated to determine the effectiveness of the control system at reducing processing variation. The experimental results show that the process control strategy reduced the variation within the mold, as seen by in‐mold pressure curves and calculated in‐mold viscosity values. Additionally, the parameters that control the automated process adjustments were investigated, showing the importance of optimization. The analysis of the correlation between in‐mold rheology and mechanical properties showed a slight variation in the mechanical properties and parts weight with a coefficient of variation of under 5%. Overall, the results demonstrate the ability of pressure‐controlled molding and automated viscosity adjustment to reduce the variability when molding a secondary feedstock. Highlights: Pressure‐controlled injection molding of recycled polypropylene.Automated closed‐loop adaptive process control methodology.Methodology resulted in a reduction in pressure variation during molding.Changes in mechanical properties and in‐mold viscosity were investigated.Results show the potential of pressure‐controlled molding at reducing variation. [ABSTRACT FROM AUTHOR]

This research investigates the correlation between polymer melt viscosity, tensile properties, and injection molding energy consumption for three grades of polypropylene: a virgin grade, a recycled grade, and a modified recycled grade. Cold runner and hot runner molds are considered. The experiments focus on characterizing the thermal and mechanical energy drawn by the injection molding machine during the cycle. The data collected from the experiments are used to calculate the embodied energy as a function of the polymer viscosity and processing conditions. The analysis of the relationship between polymer rheology and processing provided guidelines for the molded parts' embodied energy and mechanical characteristics. These guidelines and estimation techniques will support sustainable design for manufacturing practices. [ABSTRACT FROM AUTHOR]

Shear relaxation behavior for polymer melt exists in different processing techniques and influences the dimensional accuracy and production efficiency of polymer products. A micro physical and mathematical model based on microstructure of polymer chains and processing parameters was established and verified by experimental results obtained from a torque rheometer. The shear relaxation time of polypropylene degraded by di‐tert‐butyl peroxide was characterized with torque rheometer. The effects of microstructure and processing parameters on the shear relaxation time was investigated. The results showed that a wider molecular weight distribution could result in a decrease in shear relaxation time and polypropylene chains with higher molecular weight were more sensitive to molecular weight distribution. The shear relaxation time declined exponentially with shear rate and increased with internal pressure. The temperature could enhance the movement of polymer chains and reduce the shear relaxation time linearly, but polypropylene with lower molecular weight was less sensitive to temperature. The insight obtained from the mathematical and experimental results can be profoundly applied in practical process control to manufacture product with better dimensional stability and production efficiency for viscoelastic polymer. Highlights: A physical and mathematical model based on microstructure and processing parameters of molecular chains was established to explore the shear relaxation mechanism.Shear relaxation time of polypropylene degraded by di‐tert‐butyl peroxide was characterized with the help of torque rheometer.The effects of microstructure and processing parameters on shear relaxation time was investigated to optimize the manufacturing of polypropylene products. [ABSTRACT FROM AUTHOR]

The effect of compatibilizer on the nanofibril morphology, vlscoelas;ticity, mechanical properties;, and CFIM behavior of polypropylene (PP)/nylon6 (PA6) composite through a combination of in-ssitu fibrillation (INF) and chemical foam injection molding (CFIM) technologies;. The ressults; indicated that the addition of PP-g-MAH compatibilizer reduced the sSize of PA6 dispersion phasse significantly, and PA6 microfibers were uniformly distributed in the PP matrix with an average diameter of about 265nm. The existence of a microfiber network structure and the synergistic enhancement effect of phasse interface improved the mechanical strength of INF composites; significantly. The tensile sstrength and impact sStrength of the composites; are 26. 2 % and 62 % higher than thosse of pure PP, respectively. Bassed on the CFIM experiment using the sself-made endothermic-exothermic equilibrium chemical foaming agent, the INF composite foam product was; prepared with a cell size of 62 ^m and a cell density of nearly 5 X105 cells/cm3. The ass-prepared ssample obtained a decreasse in the weight by 12 %. Compared to pure PP foam, the composite foam exhibited an increase in the sSpecific tensile sStrength and impact strength by 17 % and 46 %, resspectively. [ABSTRACT FROM AUTHOR]

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP) assessed the safety of the substance 'phosphorous acid, triphenyl ester, polymer with 1,4‐cyclohexanedimethanol and polypropylene glycol, C10–16 alkyl esters', when used as an additive in all types of polyolefins. The substance is a polymer containing ≤ 13% w/w of a low molecular weight fraction (LMWF, < 1000 Da). A polyethylene sample with 0.15% w/w of the substance was used in a comprehensive set of migration tests with food simulants. The specific migration was up to 0.014 and 0.023 mg/kg in 4% acetic acid and 10% ethanol, respectively. Migration into olive oil was estimated by the Panel to be up to 5.3 mg/kg under worst‐case conditions of use. The migrating LMWF species were comprehensively identified. Those without phosphorous were either without alerts for genotoxicity or listed in Regulation (EU) 10/2011 with worst‐case migrations well below their respective specific migration limits. Toxicological studies were performed using phosphite and phosphate versions of the substance enriched in its LMWF. The substance does not raise a concern for genotoxicity. From a repeated dose 90‐day oral toxicity study in rats with a 50:50 phosphite:phosphate blend, the Panel identified a NOAEL of 250 mg/kg bw per day for each component of the blend. No delayed neurotoxicity in hens was observed. The CEP Panel concluded that the substance does not raise a safety concern for the consumer if its LMWF is not higher than 13% w/w, if it is used at up to 0.15% w/w in polyolefin materials and articles intended for contact with all food types, except for infant formula and human milk, for long‐term storage at room temperature and below, after hot‐fill and/or heating up to 100°C for up to 2 h, and if its migration does not exceed 5 mg/kg food. [ABSTRACT FROM AUTHOR]

The article presents a comparative analysis of the methods for manufacturing polypropylene Raschig rings (taking account of consumption coefficients in manufacture of thermoplastic products) on the example of mass-exchange packings for the drying tower of a sulfuric acid plant. Graphical relationships and regression equations for Raschig ring (diameter 75 mm) mass-exchange packings made of polypropylene (taking account of the manufacturing method) are presented. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Goal: Analyze the benefits of the application of recycled polypropylene in the evaporation tray of refrigerators in a multinational company of electro-electronic equipment. Design / Methodology / Approach: This research conducts a systematic literature review; performs a Life Cycle Analysis (LCA) of the polypropylene production, interpreting its results through a Pareto Diagram; and presents a case study in a multinational company of white line electro-electronic equipment. Results: The LCA results point out that propylene and the components released by the chemical plant cause the main negative externalities under the environment and human health, so that during PP production, propylene is responsible for 72% of the impacts under global warming and 86% in the face of scarcity of fossil resources. Thus, the case study proposes recycling polypropylene, following the Circular Economy guidelines by aligning the proposal with the Zero Waste policy, with modular design, with Reverse Logistics, and with Sustainable Development Goals. Research limitations: The work presents limitations inherent to literature review works, where filters are used to limit the search (limited to articles, published between 2012 and 2021 and written in English). Practical implications: The research encourages recycling, pointing out its contribution under the environmental, social and economic spheres. Originality / Value: The research presents originality and methodological value by combining qualitative and quantitative methods, and a theoretical and practical approach. Thus, it was possible to implement the research in the multinational company analyzed, and to measure the benefits obtained. [ABSTRACT FROM AUTHOR]

In this research, polypropylene (PP)–graphite composites were prepared using the melt mixing technique in a twin-screw extruder. Graphite, multi-walled carbon nanotubes (MWCNT), carbon black (CB), and expanded graphite (EG) were added to the PP in binary, ternary, and quaternary formations. The graphite was used as a primary filler, and MWCNT, CB, and EG were added to the PP–graphite composites as secondary fillers at different compositions. The secondary filler compositions were considered the control input factors of the optimization study. A full factorial design of the L-27 Orthogonal Array (OA) was used as a Design of Experiment (DOE). The through-plane electrical conductivity and flexural strength were considered the output responses. The experimental data were interpreted via Analysis of Variance (ANOVA) to evaluate the significance of each secondary filler. Furthermore, statistical modeling was performed using response surface methodology (RSM) to predict the properties of the composites as a function of filler composition. The empirical model for the filler formulation demonstrated an average accuracy of 83.9% and 93.4% for predicting the values of electrical conductivity and flexural strength, respectively. This comprehensive experimental study offers potential guidelines for producing electrically conductive thermoplastic composites for the manufacturing of bipolar fuel cell plates. [ABSTRACT FROM AUTHOR]

The emerging Additive manufacturing technologies are being adopted by different industries, which require developing new materials and procedures. Here we report the development of polypropylene (PP) based composite materials for fused filament fabrication (FFF) process with the aim of enabling fully automatic robotic repair application of plastic components in automotive industry. A key challenge in repair and joining of polyolefins, which are widely used in such applications, is understanding the interplay of microstructural features and the joining mechanisms employed to achieve a uniform and fully functional repaired components. Specifically, for components manufactured from polypropylene based material, we show that the addition of ethylene propylene diene monomer (EPDM), polyisobutylene (PIB) and carbon black (CB) successfully modifies its matrix and produces a composite material ideal for additively repairing of complex geometries found in the automotive applications. This was brought about by effective reduction of the crystallinity of the composite PP matrix from 46.2% to 34.4% and resulting in a net reduction in warpage of the FFF 3D printed samples. Further, the thermal stability of the developed composite was improved with the addition of a moderate amount of carbon filler, enabling an FFF process with higher hot‐end temperatures, which subsequently allowed for tuning of the raw material's viscosity, and hence ensuring consistent deposition of molten filaments for building successive layers. Mechanical properties' analysis revealed that the addition of 10 wt.% CB increased the true stiffness (storage modulus) by 20%, the impact strength by 62%, with the drop in ultimate tensile strength of 11%. The optimal elongation at break and toughness were achieved for the samples containing 2 wt.% CB increasing these key properties by 62% and 58%, respectively. In terms of the melt flow index (MFI), as a key rheological indicator, the measured value ranged between 12.5 and 19.0 g/10min for all compositions suitable for the FFF process. Morphological analysis of the extruded filaments and fracture surface of impact test samples showed a mesoscale interspersion of polymer phases and a proper filler dispersion in the matrix material with sizes ranging from hundreds of nanometers to hundreds of microns. The developed 3D‐printable PP composite filament was successfully used in a robotic cell to repair broken plastic lugs of a car headlight assembly. [ABSTRACT FROM AUTHOR]

In the present research, our aim is to study effects of alfa fiber content, alkali, maleic anhydride grafted polypropylene (MAPP), and the combined treatment (alkali and MAPP) on the tensile and flexural behavior of alfa fiber-reinforced polypropylene (PP) composites. These composites were produced using a single-screw extruder followed by an injection molding process. Both fibers and composites were characterized using optical and SEM microscope in order to evaluate the interfacial adhesion between the fibers and the matrix. From the main results, the tensile modulus and flexural strength of 30% untreated Alfa fiber/PP composites were found to increase significantly compared to those of PP. Meanwhile, there is no significant increase in terms of the tensile strength and the flexural modulus. Moreover, the composites with a combined treatment have shown significant effect on the tensile and flexural properties compared to untreated composites and the treated ones. The SEM observation of the morphology of alkali treated fibers exhibited an increase in the surface roughness because the removal of impurities. In addition, SEM photos of the fractured surface of composites reveal the improvement of the fibers and PP matrix interface quality by treatments, in particular the combined treatment. [ABSTRACT FROM AUTHOR]

AlPO-based zeolites(AlPO-n, n=5, 11, 17, and 34) were prepared through hydrothermal synthesis. The obtained products were incorporated into polypropylene(PP) to prepare the intumescent flame-retardant composites for enhancing its flame retardancy and thermal stability. The flammability and mechanical properties of the composites were evaluated through limiting oxygen index, vertical burning test, cone calorimetry, and tensile test. The results indicated that the PP composite containing 1 wt % AlPO-17 achieved a significantly enhancement in LOI and char residue, which increased by 34.8 % and 14.3 %, respectively, compared to pure PP. [ABSTRACT FROM AUTHOR]

To verify the utilization feasibility of the recycled polypropylene (RPP) in automobile bumper, the effects of contents of post-consumer recycled polypropylene (PCR-PP) on the impact resistance and tensile, bending, and compression properties of RPP were investigated. The thermal properties and tensile fracture morphology of RPP were also analyzed. The results indicated that the mechanical properties of the RPP exhibited a slow downward trend with an increase in the content of PCR-PP from 0 to 50 wt %. The elongation at break decreased significantly from 467 % to 210 %. At, the RPP only presented a slight change in impact resistance and tensile and bending properties at a PCR-PP content of 10 wt %, which can meet the requirements of performance for bumper materials. [ABSTRACT FROM AUTHOR]

Two types of α-form nucleating agents with a similar chemical structure, sodium bicyclo [2.2.1] hept-5-ene-2, 3- dicarboxylate (NA1) and sodium bicyclo [2.2.1] heptane-2, 3-dicarboxylate (NA2), were synthesized, and their nucleation effects on the crystallization behavior of isotactic polypropylene(iPP) was studied. The crystallization temperature and crystal morphology of iPP nucleated with the two nucleating agents were investigated using differential scanning calorimetry and polarized optical microscope (PLM). The results indicated that the crystallization peak temperature of iPP increased by 14.5 °C and 16.0 °C at 0.3 wt % NA1 and NA2, respectively. Meanwhile, the two nucleating agents could refine the spherical crystal size of iPP significantly. The nucleated iPP was characterized using wide-angle X-ray diffraction. Both of two nucleating agents were found to induce the formation of α-form crystalline polypropylene, indicating good α-form nucleation effectiveness. The mechanical properties of the nucleated polypropylene were characterized. The nucleated polypropylene exhibited an increase in tensile strength and flexural modulus at first and then tended to be stable with increasing the contents of two nucleating agents. Compared to pure iPP, the tensile strength of the nucleated iPP increased by 4.6 % and 8.6 % at 0.05 wt % NA1 and NA2, respectively. The iPP nucleated with 0.05 wt % NA1 and NA2 also showed an increase in flexural modulus by 8.2 % and 21.7 %, respectively, and its impact strength keep stable basically. [ABSTRACT FROM AUTHOR]

• PP grades and processing methods show different aging responses. • 3D-printing enhances PP aging resistance vs. conventional processes. • Recycled PP requires re-stabilization for improved aging resistance. This study investigates the weathering resistance of three polypropylene grades (impact-resistant, recycled and UV-stabilized) processed by Fused Filament Fabrication (FFF), injection and thermo-compression. Samples undergo accelerated aging, simulating conditions equivalent to six months in tropical environments with high hydrothermal and UV exposures. They are characterized by chemical, thermal, rheological, mechanical and microstructural analyses. 3D-printed impact-resistant and UV-stabilized PP resist to the considered aging conditions, attributed to the presence of stabilizers. On the contrary, the properties of recycled PP deteriorate over time due to low stabilizer concentration and the presence of impurities post-recycling. Samples processed by thermo-compression and injection display lower aging resistance compared to their 3D-printed counterparts, due to degradation and alteration in the crystalline structure induced by the processing method, like the 'skin effect' observed in injection. These findings highlight the importance of re-stabilization during recycling and the potential of 3D-printing for enhancing the aging resistance of polypropylene. [ABSTRACT FROM AUTHOR]

This paper introduces an original, fully compliant universal joint design. Many mechanisms with different dimensions are investigated. The proposed design is a single-piece compliant mechanism. The number of flexible segments is a design parameter determined as a function of transferred torque. The mechanism can be produced by additive manufacturing from polylactic acid and polypropylene. It is possible to produce the proposed design as a single piece of polypropylene by additive manufacturing and injection molding methods; thus, it has the advantage of ease in manufacturing. The proposed design's bending and torque transmission capacities are determined by applying analytical and numerical methods. Furthermore, a prototype was manufactured, and experiments were conducted. It is verified that the results of the experiments are consistent with theoretical approaches. The proposed fully compliant universal joint design has a great potential in the industry. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the total atmospheric deposition of microplastics in places near an industrial complex in Cartagena, Colombia is evaluated by taking samples at three points at different distances from the industrial zone. The samples obtained were treated to quantify and identify the type of plastic present, indicating the presence of polystyrene, polypropylene, polyethylene, polyvinyl chloride, and polyethylene terephthalate. The values of microplastics obtained were related to the climatic conditions of the areas (wind and rainfall) to determine these effects on the transport of microplastics. Values of 9472 ± 702 MP were obtained at the point closest to the industrial area and 1455 ± 14 MP at the farthest point, within which a greater proportion were fibers. In this study, it was also possible to determine that the microplastics most affected by the wind were the fragments. [ABSTRACT FROM AUTHOR]

In this study, a cold atmospheric pressure plasma jet was conducted to modify glass fiber. To improve the interfacial bonding properties of glass-fiber-reinforced polypropylene composites, SiOx nanoparticles were polymerized on the fiber surfaces. The properties of the modified fibers and composites, including surface morphology, chemical composition, wettability and interfacial bonding properties, were studied systematically to understand the influence of gas flow rate of the carrier on the modification effect of glass fiber. The optimal parameter was determined to be a gas flow rate of 40 mL/min. The results indicated that after plasma treatment, the fibers achieved an improvement in the surface energy by 43.18% compared to that of the control samples. The interlaminar shear strength of glass-fiber-reinforced polypropylene composites was improved by 30.79% when compared to the control. The high surface roughness and the content of oxygen-containing polarity functional groups in the glass fiber after the plasma treatment promoted an enhancement in interlaminar shear strength. [ABSTRACT FROM AUTHOR]

Manufacturing polypropylene (PP) composites to meet customers' needs is difficult, time-consuming, and costly, owing to the ever-increasing diversity and complexity of the corresponding specifications and the trial-and-error method currently used to satisfy the required physical properties. To address this issue, we developed three models for predicting the physical properties of PP composites using three machine learning (ML) methods: multiple linear regression (MLR), deep neural network (DNN), and random forest (RF). Further, the industrial data of 811 recipes were acquired to verify the developed models. Data categorization was performed to account for the differences between data and the fact that different recipes require different materials. The three models were then deployed to predict the flexural strength (FS), melting index (MI), and tensile strength (TS) of the PP composites in nine case studies. The predictive performance results differed according to the physical properties of the composites. The FS and MI prediction models with MLR exhibited the highest R2 values of 0.9291 and 0.9406. The TS model with DNN exhibited the highest R2 value of 0.9587. The proposed models and study findings are useful for predicting the physical properties of PP composites for recipes and the development of new recipes with specific physical properties. [ABSTRACT FROM AUTHOR]

The study of the presence of bisphenol analogs in the environment has been very relevant in recent years because their toxic potential has been discovered, and since they are not regulated like bisphenol A, their use and presence in industry has been excessive. This study identifies and quantifies for the first time the presence of bisphenol A and four uncommon bisphenol analogs in waste from polypropylene (PP) and polyethylene terephthalate (PET) production processes that may originate from the degradation of some compounds used during resin synthesis in Colombia to determine the effectiveness of removal of these components. The data obtained show that the treatments used in these waters are insufficient to eliminate 40% of the bisphenols present in them, and when evaluating the profiles of compounds, it is clear that the compound with the highest removal during the PP process was D-BPA-1, while the compound with the highest removal during the PET process was D-BPA-4, indicating that identification and elimination systems for bisphenols are rudimentary. [ABSTRACT FROM AUTHOR]

Because of its toxicity and impacts on the environment and human health, bisphenol A (BPA) has been controlled in numerous industrialized nations, increasing demand for bisphenol analogues (BP) for its replacement. However, the consequences of these chemicals on the environment and the health of persons exposed to their emissions are still being researched. The emissions from polypropylene manufacturing facilities in Colombia and Brazil were evaluated in this study, and the presence of bisphenol A and four BPs was detected among the gaseous compounds released, with total concentrations of BPs (∑BP) between 92 and 1565 ng g−1. As the melt flow index (MFI) of the polymer rises, so does the quantity of volatiles in its matrix that are eliminated during deodorization, indicating that the MFI and the amount of bisphenol released have a directly proportional connection. [ABSTRACT FROM AUTHOR]

Oleamide is used as a lubricant in the manufacturing and application of polypropylene (PP) medical devices. Samples of PP were prepared with 0, 1500, and 15 000 ppm oleamide content as lubricant. The samples were either left non‐sterile, sterilized with ethylene oxide (ETO), γ‐radiation (γ) or autoclaved (A) and stored for up to 4 weeks. To determine the oleamide bulk‐to‐surface distribution depending on sterilization method and storage time an extraction method and a washing technique were applied. The oleamide content was determined by gas chromatography (GC‐FID) and compared with the coefficient of friction (COF). The COF dependent on the measured lubricant content at the surface. The content of lubricant on the surface depends on the type of sterilization: ETO increased the lubricant content to some extent, γ‐sterilization and autoclaving reduced it. After storage, no migration of the lubricant to the surface could be detected. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The high cost of biofabricated titanium mesh plates can make them out of reach for hospitals in low-income countries. To increase the availability of cranioplasty, the authors of this work investigated the production of polymer-based endoprostheses. Recently, cheap, popular desktop 3D printers have generated sufficient opportunities to provide patients with on-demand and on-site help. This study also examines the technologies of 3D printing, including SLM, SLS, FFF, DLP, and SLA. The authors focused their interest on the materials in fabrication, which include PLA, ABS, PET-G, PEEK, and PMMA. Three-dimensional printed prostheses are modeled using widely available CAD software with the help of patient-specific DICOM files. Even though the topic is insufficiently researched, it can be perceived as a relatively safe procedure with a minimal complication rate. There have also been some initial studies on the costs and legal regulations. Early case studies provide information on dozens of patients living with self-made prostheses and who are experiencing significant improvements in their quality of life. Budget 3D-printed endoprostheses are reliable and are reported to be significantly cheaper than the popular counterparts manufactured from polypropylene polyester. [ABSTRACT FROM AUTHOR]

The lack of suitable destinations for plastics materials can be a global environmental problem. The alternative use of materials for sustainable construction encourages the standardization of waste and promotes effective social, environmental and economic gains at the local level and ensures savings and income for communities. The aim of this paper is the development, manufacture, and characterization of PP and HDPE recycled polyolefin blocks as masonry components in civil construction. These blocks were manufactured by the rotational molding process. Besides this, the mechanical, physical, impact and flammability properties of the blocks were studied. In conclusion, HDPE showed better behavior than PP in tests realized. [ABSTRACT FROM AUTHOR]

Additive manufacturing processes are still on the way from a prototyping process to an established serial production process. Often the limiting factors are the variety and costs of materials compared with standard materials. Polypropylene is a commonly used material in series production. The processing of polypropylene in additive‐ and extrusion‐based manufacturing processes is still a challenge. A big issue in pellet‐based large scale additive manufacturing of polypropylene is to achieve dimensional accuracy of the printed parts. Due to the semi‐crystalline nature of polypropylene and its low adhesive force on standard printing surfaces (aluminum) the fabricated parts tend to warp and deviate from the geometric shape. In this paper the influence of a melt adhesive and different filler types (glass fibers, glass bubbles, and talcum) on the warpage behavior of 3D printed polypropylene parts is investigated. Another issue in additive manufacturing is the mechanical properties of the fabricated parts compared to injection molded parts. The mechanical properties of 3D printed parts often show a dependency on the print direction, especially in case of using fillers with an anisotropic shape (fibers). In this study the influence of different fillers on mechanical properties and process indicated orientation is analyzed. [ABSTRACT FROM AUTHOR]

It is known from the literature that freedom from macroscopic defects (voids) is an essential prerequisite for good mechanical properties of 3D‐printed components manufactured using fused filament fabrication. The present study further shows that the morphology and mechanical properties of void free components are significantly influenced by the choice of process parameters. Components that were printed at low temperatures and high speeds show fair and inhomogeneous supermolecular morphology, clearly visible weld seams and a special flow‐induced staggered structure of the individual strands laid‐up. At higher magnification in the optical microscope, transcrystalline structures are visible starting from the contact area between the strands, that is, crystallization has started at the interface between the strands and is moving forward towards the center of the strands. In contrast, the samples printed at high temperatures and low speeds show a homogeneous supermolecular morphology with overall larger spherulites and a higher degree of crystallinity and compared to the specimens printed with the low temperature/high speed‐set much better mechanical properties. A numerical simulation of the temperature at the contact point of the strand emerging from the hot nozzle and the cooled strand neighbor agrees well with the measured behavior. The thermal simulation thus enables the temperature to be calculated at any point in time in the welding contact and thus access to the local thermal conditions during joining, cooling and the formation of the morphology. [ABSTRACT FROM AUTHOR]

Copyright of Industria Textila is the property of Institutul National de Cercetare-Dezvoltare pentru Textile si Pielarie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, a multivariate statistical process control was used to analyze the abnormal samples derived from the deviation of optimum processing parameters. The experimental samples derived from the optimum processing parameters were applied as the optimal historical data to determine the control limit, and then the T 2 value was obtained from Hotelling's T 2 method. If the T 2 value exceeds the control limit, the corresponding sample is considered as abnormal. After that, the Runger, Alt and Montgomery method is used to decompose the abnormal T 2 value. Then, each quality characteristic value can be obtained and the corresponding decision tree classifier can be implemented. To improve the classification accuracy, we classify the decision tree classifier into single–double identification, single-factor abnormality and double-factor abnormality. For the individual classification test, the result showed that the accuracy of single–double identification was 98.6%, the single-factor abnormality classification was 100% and the double-factor abnormality classification was 96.0%. For the combination classification test, we can get a 98.6% accuracy rate for the single–double identification, 98.3% accuracy rate for the single-factor abnormality classification and 95.3% accuracy rate for the double-factor abnormality classification. Therefore, it can be confirmed that the proposed methods in this study can effectively identify abnormal samples and establish a fault processing parameter diagnosis system for melt spinning machines. [ABSTRACT FROM AUTHOR]

This experimental study is conducted to investigate the effects of boric acid additive into polypropylene in terms of microstructure formation and thermal properties. Boric acid granules are added into pure polypropylene at three mass rates of 0.5, 1.5, and 2.5% which are notated as PP/BA-0.5, PP/BA-1.5, and PP/BA-2.5, respectively. The pure polypropylene material (pure PP) and boric acid reinforced polypropylene composite materials (PP/BA) are manufactured in an injection molding machine. The microstructure of composite materials is examined with an SEM (scanning electron microscope) device. Thermal analyses are conducted by using a TGA (thermogravimetric analyzer) device. In addition, thermal conductivities of composite materials are measured between 10 and 50 °C temperatures. SEM images show that boric acid at 0.5% additive rate forms a homogeneous composite by uniformly spreading the polymer chains, while boric acid at high additive rates of 1.5% and 2.5% becomes agglomerated within the polymer. TGA analyses show that the initial evaluation degradation temperature (Ti) tends to decrease with the addition of boric acid. Thermal conductivity for all examined materials almost linearly increases with temperature at a slope of about 0.0004 [(W m−1 K−1)/K]. Thermal conductivity is reversely proportional to the boric acid additive rate. The thermal conductivity for 2.5% boric acid added polypropylene is about 5% less than pure polypropylene. [ABSTRACT FROM AUTHOR]

In the current study, minimization of waste in terms of sack rejection at a polypropylene bag manufacturing process is achieved. The Six Sigma DMAIC (Define, Measure, Analyze, Improve, Control) approach is adopted which results in 50% waste reduction and a considerable cost saving. The sack rejection is brought to 1.20% from the previous average waste of 2.80% using DMAIC. It is found that this high rejection rate of 2.80% is due to the low fabric strength obtained at the weaving section, which in turn occurred due to the lower tape tenacity values obtained from the extrusion section. Hence, experimental design is conducted at the extrusion department and it is found that the two interacting factors are playing a significant contribution to the process variation and hence result in lower tape-tenacity (i.e., less than 6 g/denier). The two interacting factors included the "water bath temperature" and "line speed" of the extrusion process, with a p-value less than 5%. By further analysis, the optimal level of these significant factors is found. They are 300 m/min for "line speed" and 40⁰C for "water bath temperature. At these settings, the extrusion process produces optimal tape-tenacity results (i.e., at least 6 g/denier), which ultimately results in minimum waste in terms of sack rejection waste. The objective of the study includes finding the significant factors contributing to the process variation. Also controlling those factors to the optimal levels to achieve minimum wastage and considerable cost saving. The methodology and findings of the present study can be generalized to the polypropylene bag manufacturing plants and the process efficiency can be enhanced. [ABSTRACT FROM AUTHOR]

Horizontal stirred bed reactors are widely used in the commercial manufacturing of polypropylene. However, a comprehensive understanding of the particle dynamics in horizontal stirred bed reactors remains elusive, primarily due to the lack of detailed experimental data. In this work, we studied the influence of operating parameters on the particle flow dynamics in a laboratory-scale horizontal stirred bed reactor using single-photon emission radioactive particle tracking. The results show that the general solids flow behavior is strongly affected by both the agitator rotation speed and reactor fill level. Operation at low rotation speed and low fill level results in solids flow with poor radial and circumferential distribution due to internal bed circulation. On the contrary, at increased rotation speeds and fill levels, solids motion throughout the bed is continuous resulting in excellent solids distribution. The solids circulation was found to increase for both an increase in rotation speed and reactor fill level. The axial dispersion coefficient, on the other hand, shows a linear relation with the rotation speed, but no conclusive relation between the axial dispersion coefficient and the reactor fill level was found. • A horizontal stirred bed reactor is studied using radioactive particle tracking. • The flow pattern, solid circulation, and axial dispersion are analyzed. • Fill level and rotation speed have a significant influence on the particle dynamics. [ABSTRACT FROM AUTHOR]

Abstract Surgical mesh materials made from fibres of polypropylene (PP) have been widely used for over fifty years. However in recent times the use of these materials has been called into question for certain surgical operations, known as "pelvic organ" or "transvaginal" procedures. This article reviews the current state of knowledge and uses some simple biomechanics analysis in order to make recommendations for future work. My conclusion is that the failure rate of PP mesh in pelvic organ products is unacceptably high whilst being much lower when it is used for hernia repair. The precise mechanical environment is difficult to quantify but a tentative conclusion is that failure by purely mechanical mechanisms (fatigue and creep) is unlikely. There is some evidence for environmental degradation (i.e. stress-corrosion) but this is highly contested in the literature. On balance my conclusion is that stress-corrosion failure is the most likely explanation but currently no experimental results exist to prove conclusively that this failure mechanism occurs in vivo. Further work is needed, especially the analysis of explanted material, to resolve this urgent problem. [ABSTRACT FROM AUTHOR]

A nanocomposite consisting of polypropylene (PP)/nanoclay (montmorillonite) was prepared by means of a melt‐compounding process with the use of a twin‐screw extruder. Because of the complex dispersion of polar and hydrophilic clays that have many cations in the nonpolar and hydrophobic PP, amino‐silane was introduced to modify the surface of the clays. Also, to improve the compatibility of the modified nanoclay with PP, a PP‐graft‐maleic anhydride was used as a compatibilizer. From Fourier transform infrared spectroscopy analysis and the mechanical property test results, it was confirmed that the surface of the nanoclay was properly modified, and it was successfully dispersed in the PP matrix. The composite was investigated by electron microscopy to analyze its morphology and the degree of dispersion of the nanoclay. An analysis of oxygen permeability according to nanoclay content was performed, and it was found that the higher nanoclay content makes the decrease in oxygen permeability. In addition, a shelf‐life test was carried out to determine the relationship between decreased oxygen permeability and food preservation performance. The preservation performance of the food package prepared with the resin made in this study was improved because of the improvement in mechanical properties and oxygen barrier property. [ABSTRACT FROM AUTHOR]

Ultrasonic oscillation as a new polymer processing technology, was introduced into the polymer melt to improve the high melt strength Polypropylene (HMSPP) foaming ability, the effect of the ultrasonic oscillation power, Azodicarbonamide (AC) and talc content on the cell morphology, cell size, apparent density, cell density and nucleation density of the HMSPP foam was systematically studied. When the ultrasound and talc were introduced into the HMSPP melt, the HMSPP foam had a larger cell density and smaller the size as well as more uniform distribution. Interestingly, when the talc was introduced into the HMSPP, the cell morphologies changed from sphere to oval. Compared to the HMSPP foam without ultrasonic oscillation, the minimum thermal conductivity of the HMSPP foam with ultrasonic power 100 W reached 0.055 W/mK. When the talc was introduced into HMSPP melt, the average sound transmission loss value of the HMSPP foam were enhanced, and reached 30.37 dB, which was 13.7% higher than that of the HMSPP foam without talc and ultrasonic oscillation. The ultrasonic‐assisted extrusion foaming had a promising to construct a new method to continuously and rapidly fabricate polymer foam with low thermal conductivity and excellent sound insulation properties. POLYM. ENG. SCI., 58:1678–1684, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The aim of this work is to model the water absorption mechanism of the polypropylene/date palm fibers composite materials after their exposure at different immersion conditions. For short immersion period, a model combining the Fick’s law and the time temperature stress principle has been proposed to describe the water absorption mechanism. However, it has been noted that, after a saturation time, the water diffusion mechanism leads to a physical degradation and a mass loss into the composite material, especially under high temperatures and long times of water immersion. Microscopic observations have revealed a decrease of the interfacial adhesion between the fibers and the matrix and fiber degradations. A general new model describing the evolution of the water uptake mechanism and the degradation phenomenon has been also proposed in the present work. A good agreement between the theoretical and experimental data has been obtained. [ABSTRACT FROM AUTHOR]

ABSTRACT: Blast furnace slag (BFS) is a byproduct of the blast furnace in iron industry. Due to its composition and structure, BFS is suggested as a promising functional filler that can potentially improve the property profile of polypropylene. To overcome the lack of compatibility between BFS and polypropylene (PP), two coupling agents, vinylethoxysiloxane homopolymer silicon and methacryloxypropyltrimethoxysilane, are utilized for treating the BFS surface. The influence of each coupling agent on the BFS–PP compound properties is investigated in this work. It is observed that both coupling agents equally increase the complex shear viscosity and thermal conductivity of the modified BFS compounds by 10% and 12%, respectively, compared to their unmodified counterparts. The degree of crystallinity of the modified compounds also increased by more than 25%. While the tensile stiffness and yield strength levels are found to be comparable for all compounds, the strain at break of some modified BFS compounds is doubled. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46535. [ABSTRACT FROM AUTHOR]

Sodium bicyclic[2,2,1]heptane dicarboxylate (HPN-68) is a highly effective commercial isotactic polypropylene (iPP) nucleating agent. In this paper, isothermal crystallization behaviors of iPP nucleated with HPN-68 were investigated using differential scanning calorimetry (DSC). The calculation model of Lamberti based on the Avrami method was used for obtaining nucleus density from calorimetric crystallization curves recorded under isothermal conditions. A number of growth rate data have been obtained with the Lauritzen and Hoffman equation. General procedures to predict nucleus density by simple DSC measurements were described and applied successfully to iPP. Addition of HPN-68 shortened crystallization half-time (t1/2) and increased the crystallization rate of iPP, eventually the nucleus density of iPP nucleated with HPN-68 for finishing crystallization under higher crystallization temperature was larger than that of virgin iPP, leading to larger crystallization rate and shorter cycle time. [ABSTRACT FROM AUTHOR]

Long-chain branched polypropylenes were synthesized from a maleic anhydride grafted polypropylene (PPg). Different levels of branching were generated by reactive processing using four chain-linking agents: glycerol, 1,4-butanediol, 1,4-phenylenediamine, and the epoxy resin bisphenol-A diglycidyl ether. The results from Fourier transform infrared and size-exclusion chromatography confirm the grafting of the chain-linking agents onto grafted polypropylene and the generation of long-chain branches. In addition, the rheological and morphological results show that 1,4-phenylenediamine produces the largest increment of branching at significantly lower concentrations than the other chain-linking agents. Moreover, 1,4-phenylenediamine gives place to branched polypropylenes with narrower distribution of molecular structures. [ABSTRACT FROM AUTHOR]

A triangle arrayed triple‐screw extruder was used to prepare in situ polypropylene (PP) microfibrillar composites (MFCs) by direct extrusion, in which polyamide 6,6 (PA66) and poly(butylene terephthalate) (PBT) were used as dispersed phases while PP as matrix phase. The morphological evolution of the dispersed phase were investigated by SEM through taking samples along the extruder from different positions. The results showed that the fibrillating mechanism of PA66 was entirely different from that of PBT. Dynamic oscillatory shear rheological properties were used to analyze the effect of different types of in situ microfibrils on the rheological properties of MFCs. The obtained results showed that the storage modulus and complex viscosity of both PP/PA66 and PP/PBT MFCs were improved with increasing fibrillar aspect ratios. The loss tangent tan δ at low frequencies decreased with the increase of fibrillar aspect ratio. Moreover, the gel point concentration of PP/PA66 composite was lower than that of PP/PBT composite. [ABSTRACT FROM AUTHOR]

• A mechanical metamaterial with tunable normal-strain shear coupling is presented. • A few geometric parameters allow for shear coupling in a broad range. • The three-dimensional design allows for spatial positioning with one-dimensional strain. Different designs for mechanical metamaterials with tunable normal-strain shear coupling effect have been demonstrated over the last years. Their adjustable shear deformation makes them suitable as building blocks for soft robotics applications or structures with a desired deformation behavior, such as shape morphing structures. Herein, we present a modified 2.5D and 3D chiral-based mechanical metamaterials with tunable normal-strain shear coupling effect and Poisson's Ratios close to zero. Advancing from conventional chiral-based metamaterials by introducing additional geometric freedoms into the design of the unit cell, a broad range of shear deformations, compression moduli and porosities can be achieved. 2.5D specimens with selected geometric parameters were additively manufactured with polypropylene using Fused Filament Fabrication. Compression tests were performed to investigate the mechanical properties and shear deformation. Two different numerical models were employed using ABAQUS to study the influence of the geometric parameters onto the mechanical properties and were verified by the experiments. The numerical material models were based on three-point-bending test data. The three-dimensional design was investigated with numerical simulations based on a homogenization approach to cover a broad range of geometric parameters. [ABSTRACT FROM AUTHOR]

The Mediterranean is an ecosystem that faces more and more microplastic pollution every day. This causes the whole of the Mediterranean to face the negative effects of plastic pollution. This study examines the state of plastic debris and fouling organisms found on it in one of the areas most affected by plastic pollution, Mersin Bay. As a result, a total of 3.88 kg plastic (mean = 0,97 kg; n = 120; 2670 item/km 2 ; 86,3 kg/km 2 ) was collected and based on the ATR-FTIR analysis, it was determined that this total contained 9 types of plastics. 17 different fouling sp ecies belonging to 6 phylum (Annelida, Arthropoda, Bryozoa, Chordata, Cnidaria, Mollusca) 7 class and 11 order were discovered on plastics. Spirobranchus triqueter , Hydroides sp. and Neopycnodonte cochlear were the most abundant species. In the end, the example of Mersin Bay shows that plastic debris as a substrate can contain a very high diversity of life just like natural substrates. [ABSTRACT FROM AUTHOR]

The use of an adhesive for mesh fixation in hernia repair reduces chronic pain and minimizes tissue damage in the patient. This study was designed to assess the adhesive properties of a medium-chain (n-butyl) cyanoacrylate glue applied as drops or as a spray in a biomechanical and histologic study. Both forms of glue application were compared to the use of simple-loose or continuous-running polypropylene sutures for mesh fixation. Eighteen adult New Zealand White rabbits were used. For mechanical tests in an ex vivo and in vivo study, patches of polypropylene mesh were fixed to an excised fragment of healthy abdominal tissue or used to repair a partial abdominal wall defect in the rabbit respectively. Depending on the fixation method used, four groups of 12 implants each or 10 implants each respectively for the ex vivo and in vivo studies were established: Glue-Drops, Glue-Spray, Suture-Simple and Suture-Continuous. Biomechanical resistance in the ex vivo implants was tested five minutes after mesh fixation. In vivo implants for biomechanical and histologic assessment were collected at 14 days postimplant. In the ex vivo study, the continuous suture implants showed the highest failure sample tension, while the implants fixed with glue showed lower failure sample tension values. However, the simple and continuous suture implants returned the highest stretch values. In the in vivo implants, failure sample tension values were similar among groups while the implants fixed with a continuous running suture had the higher stretch values, and the glue-fixed implants the lower stretch values. All meshes showed good tissue integration within the host tissue regardless of the fixation method used. Our histologic study revealed the generation of a denser, more mature repair tissue when the cyanoacrylate glue was applied as a spray rather than as drops. [ABSTRACT FROM AUTHOR]

ABSTRACT Present work concerns to the study of the dynamic mechanical and thermal responses of selected polypropylene (iPP)/mica composites with a modified interface from the matrix side by using a p-phenylen- bis-maleamic acid grafted atactic polypropylene, coming from a byproduct of industrial polymerization reactors. Thus, the study is mainly focused on the 75/25 iPP/mica ratio since it was identified in previous works as providing the maximum inter mica particle distance to assure they should participate in the overall process of dissipation of the mechanical energy supplied to the composites. Hence, the present dynamic mechanical analysis discussion tries to correlate the damping responses of the injection-molded composites with those previously obtained but over compression molded composites as the basis of further studies all along the compositional iPP/mica map. Therefore, the latter let us, on the one hand, to follow how the main values of the different dynamic mechanical analysis parameters vary because of the interfacial modifier presence, and on the other, to develop a robust correlation between them and the corresponding macroscopic mechanical parameters. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45366. [ABSTRACT FROM AUTHOR]