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This study explores the reinforcement potential of nano graphene in a poly latic acid (PLA) matrix. The present work introduces a framework to select reinforcement for the formation of composite that will be feasible to manufacture by using additive manufacturing. Main objective of this research work is to develop the composition of PLA-nano graphene composite to make it feasible to be printed by fused deposition modeling based additive manufacturing. In order to achieve the same, the problem of selecting a reinforcement and constituents of composite is discussed in detail. Based on the literature review, four compositions (1.5 %, 3 %, 4.5 %, and 6 % nano-graphene by weight to PLA) are prepared to find out the optimum composition. In this study, the effects of nano graphene loading on the melt flow behaviour of PLA-graphene composites for extrusion-based fused deposition modeling (FDM) were investigated. The objective was to determine the optimal nano graphene loading that would yield the optimum melt flow index with desirable best mechanical properties. Tests have been performed for three samples of each of four compositions 1.5 %, 3 %, 4.5 %, and 6 % nano Graphene by weight to PLA. The results found that with increasing nano graphene content, both the melt flow index as well as mechanical properties increased significantly. However, when the nano graphene loading reached 6 wt%, a decrement in these parameters was observed due to the agglomeration of fillers onto each other within the composite structures. Therefore, it is concluded that out of the remaining compositions (1.5 %, 3 %, and 4.5 % nano graphene by weight to PLA), 4.5 wt% is an optimal loading level for obtaining desired processing performance and mechanical properties from PLA-graphene composites for FDM application. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) is one of the established thermoplastics with inherent piezoelectric characteristics. In the past two decades, a lot of work has been reported on the use of virgin Polyvinylidene fluoride thermoplastics for sensing applications. But hitherto little has been reported on 3D printing of secondary (2°) recycled Polyvinylidene fluoride as a smart energy storage device (ESD). This work is focused on exploring the possibilities for 3D printing of smart energy storage device comprising of Polyvinylidene fluoride having (melt flow index (MFI) 30 g /(10 min) as per ASTM D 1238) reinforced with MnO2, graphite, ZnCl2, and N H 4 Cl in different weight proportions to form a feedstock filament for fused deposition modeling (FDM) in the first stage. The MFI of Polyvinylidene fluoride composites reinforced with MnO2, graphite, ZnCl2, and N H 4 Cl (34.095, 8.480, 42.982, 11.807 g /(10 min) respectively) was ascertained for possible 3D printing on FDM. The results suggest that even with an acceptable MFI of prepared 2° recycled Polyvinylidene fluoride, the same was not printable. Further for possible 3D printing on FDM, low-density polyethylene (LDPE) was blended in a Polyvinylidene fluoride matrix, and successful 3D printing-based energy storage device was prepared in the second stage. The study also highlights the mechanical, and morphological properties of Polyvinylidene fluoride composites have been improved after processing with a twin-screw extruder (TSE) by using different input parameters (screw temperature (T), screw speed (S), and load (L)). Overall, the study suggests that the proportion of LDPE, MnO2, graphite, ZnCl2, and N H 4 Cl has a significant effect on the rheological, mechanical, and morphological properties. The results have been supported with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier-transformed infrared spectroscopy (FTIR) analysis. [ABSTRACT FROM AUTHOR]

Melt flow index (MFI) is one of the physical properties of degradable plastics that must be considered in the production of well-degradable plastics. This is because MFI affects some of the mechanical properties of degradable plastics. This study aims to model the MFI of degradable plastics using two nonparametric methods, namely principal component analysis (PCA) and deep neural networks (DNN). PCA was used to reduce the dimension of the input data set in the first stage of modeling. Then, the DNN was used as an alternative model to estimate the accuracy of predicting the MFI of degradable plastics. The result shows that the model accuracy is very good, with a least mean squared error of 0.00004 and a mean absolute percentage error of 2.46% using 4 principal components. The study also highlights the advantages of combining PCA and DNN in modeling MFI for degradable plastics and provides some ideas for further research. [ABSTRACT FROM AUTHOR]

In the present work, a combination of virgin polypropylene and E-glass fiber was subjected to ten (10) reprocessing cycles via extrusion and compression molding techniques to mimic recycling and its impacts on the bending properties of the composites. The samples were characterized using Fourier transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), scanning electron microscopy (SEM), and melt flow index (MFI). The results revealed a gradual depreciation in flexural properties after each reprocessing cycle. The XRD analysis indicated a substantial reduction of peak intensities, degrees of crystallinities, and average crystallite sizes, explaining the lowered flexural properties in addition to a possible reduction in glass fiber lengths (fiber attrition). Melt-processing behavior shows a progressive increase of MFI from 7 to 19.16 g/10 min, confirming the probable damage in molecular weight and loss of complex viscosity. Chemical and structural analysis showed no alteration in the polypropylene major functional groups. It is concluded that the reductions in molecular weight and composites' properties occurred due to chain scission from recycling effects; hence, glass fiber-reinforced polypropylene composites can be recycled only three (3) times unless it is refreshed by the addition of virgin parts to compensate for the lost property. [ABSTRACT FROM AUTHOR]

The high-density polyethylene (HDPE) production requires a precise control of process variables which are controlled by various instruments throughout the production process. Among all of them, two stand due to their importance: (i) the solids concentration (SC), which is measured by a nuclear mass measurer, and (ii) the melt flow index (MFI), that is done with a delay of 3 h from reactor. Accurate calculation and variable measurement are of great importance, and thus, the use of intelligent control tools is increasingly required. This study aimed to develop an artificial neural networks (ANNs)-based virtual sensor for the prediction of SC and MFI in the production of HDPE. Using real process data, principal component analysis was used to reduce the number of input variables and then several ANNs were trained. The results showed that the Levenberg–Marquardt algorithm was the most effective. The best result indicated that two ANNs, one for each variable, were necessary: ​​The ANN for SC had an average error of 0.12%, and the ANN for the MFI had an average error of 3.8%. Finally, this study showed that a virtual neural sensor can be an accurate tool for predicting variables in real industrial processes. [ABSTRACT FROM AUTHOR]

On the basis of the characteristics of low-density polyethylene determined experimentally from the geometric dimensions of the extruder parts and COMSOL MULTIPHYSICS software a digital model of the apparatus was created, and the flow rate of the polymer melt from the extruder nozzle was calculated hydrodynamically. The agreement between the experimentally measured polymer flow rate and the value obtained from the model lies within the permissible error. This establishes the adequacy of the digital twin model, which will be used to predict the viscosity characteristics of composite materials based on low-density polyethylene and the technological regimes of their production by blending in the extruder. [ABSTRACT FROM AUTHOR]

3D printing is one of the plastic recycling processes that deliver a mechanically sustainable product and may be used for 4D printing applications, such as self-assembly, sensors, actuators, and other engineering applications. The success and implementation of 4D printing are dependent on the tendency of the shape memory with the action of external stimuli, such as heat, force, fields, light, and pH. Acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) are the most common materials for fused filament fabrication-based 3D printing processes. However, the low-shaped memory tendency on heating and weaker and less rigidity of ABS limit the application domains. PLA is an excellent responsive behavior when the action of heat has high stiffness. The incorporation of PLA into ABS is one of the solutions to tune the shape memory effect for better applicability in the 4D printing domain. In this study, the primary recycled PLA was incorporated into the primary recycled ABS matrix from 5 to 40% (weight%), and composites were made by extrusion in the form of cylindrical filaments for 4D printing. The tensile and shape memory properties of the recycled ABS–PLA composites were investigated to select the best combination. The results of the study were supported by fracture analysis by shape memory analysis, scanning electron microscopy, and optical microscopy. This study revealed that the prepared ABS–PLA-based composites have the potential to be applied in self-assembly applications.

This work focuses on studying the influence of coupling agents on the degradation in the mechanical properties of Polypropylene (PP)/wood composites. Maleic anhydride polypropylene (MAPP) was used as a coupling agent between the wood flour and PP matrix. As the coupling agent plays an important role in the stability of the WPC, a 10 wt% wood flour was mixed with PP granules along with a UV stabilizer and varying percentages (1, 3, 5 wt%) of MAPP in a twin-screw extruder to obtain PWC granules. The composite granules were injection molded to produce tensile samples for the mechanical characterization of the composites. To test the environmental degradation of the PWCs, the tensile samples were exposed to the environmental conditions for 0, 336 h (14 days), and 672 h (28 days) prior to testing. After the specified exposure time, the samples were mechanically characterized using tensile testing. The degradation characteristics of the WPCs were quantified in terms of the failure strains of the composite with exposure time. The experiments were designed, and various analyses, including ANOVA, regression equation, and prediction tests, were carried out to investigate the impact of parameters on the failure strain of the PWCs. Moreover, the study aimed to examine the effect of parameters such as MAPP and time, on the failure strain of the composites. From the experimental results, it is concluded that the composites containing 1 wt% of MAPP showed superior retention in the degradation of composites when compared with 3 and 5 wt% MAPP content.

High-density polyethylene polymer (HDPE) and carbon black (CB) were utilized to create HDPE/CB composites with different filler concentrations (0.0, 2.0, 4.0, 6.0, 8.0, 10.0, 16.0, 20.0, and 24.0 wt.%). The composites were extruded into filaments, which were then utilized to fabricate 3D-printed specimens with the material extrusion (MEX) method, suitable for a variety of standard mechanical tests. The electrical conductivity was investigated. Furthermore, thermogravimetric analysis and differential scanning calorimetry were carried out for all the HDPE/CB composites and pure HDPE. Scanning electron microscopy in different magnifications was performed on the specimens' fracture and side surfaces to investigate the morphological characteristics. Rheological tests and Raman spectroscopy were also performed. Eleven different tests in total were performed to fully characterize the composites and reveal connections between their various properties. HDPE/CB 20.0 wt.% showed the greatest reinforcement results in relation to pure HDPE. Such composites are novel in the MEX 3D printing method. The addition of the CB filler greatly enhanced the performance of the popular HDPE polymer, expanding its applications. [ABSTRACT FROM AUTHOR]

In metal injection molding, the fluidity of the polyformaldehyde (POM)-based binder is poor, which causes the appearance of defects such as insufficient injection and wrinkles, thus reducing the dimensional accuracy of products. To solve this problem, different Melt Flow Index (MFI) of POM was used to prepare metal injection molding (MIM) 17-4PH stainless steel feedstocks. In this investigation, the fluidity and uniformity of feedstocks prepared by different POM and the effects of different feedstocks on each MIM process were analyzed. The results showed that with the increase of MFI value of POM, the fluidity of feedstock became better, but the uniformity became worse. The feedstock prepared by mixing POM with MFI value of 70 g/10 min and 230 g/10 min has the best dimensional accuracy about ± 0.12%. Therefore, by selecting POM-specific MFI values, it is expected to improve the rheological properties of POM-based binders and obtain products with higher dimensional accuracy. [ABSTRACT FROM AUTHOR]

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The study focused on the evaluation of the influence of inhibitory compounds such as hydrogen sulfide (H2S) and methanol (CH3OH) on the catalytic productivity and properties of the polymers in the polymerization process with the Ziegler–Natta catalyst. The investigation involved experimental measurements, computational calculations using DFT, and analysis of various parameters, such as molecular weight, melt flow index, xylene solubility, and reactivity descriptors. The results revealed a clear correlation between the concentration of H2S and methanol and the parameters evaluated. Increasing the H2S concentrations, on average by 0.5 and 1.0 ppm, resulted in a drastic decrease in the polymer's molecular weight. A directly proportional relationship was observed between the flow rate and the H2S concentration. In the case of methanol, the change occurred from 60 ppm, causing a sharp decrease in the molecular weight of the polymer, which translates into an increase in the fluidity index and a decrease in solubility in xylene. The presence of these inhibitors also affected the catalytic activity, causing a reduction in the productivity of the Ziegler–Natta catalyst. Computational calculations provided a deeper understanding of the molecular behavior and reactivity of the studied compounds. The computational calculations yielded significantly lower results compared to other studies, with values of −69.0 and −43.9 kcal/mol for the Ti-CH3OH and H2S interactions, respectively. These results indicate remarkable stability in the studied interactions and suggest that both adsorptions are highly favorable. [ABSTRACT FROM AUTHOR]

The mechanical properties improving filler introduction into polymer filaments often lead to the formation of defects in 3D-printed products. Studying the bulk modification of polyethylene terephthalate glycol (PETG) filaments with 0.5–1.5 wt% of natural shungite and molybdenum disulfide, we found the melt flow index (MFI) value reduced by 18%–30%. We investigate the effect of bulk modification on the filaments' rheological properties, develop a technique that eliminates typical additive prototyping defects by regulation of the extrusion parameters in Cura slicing software, and propose an effective method for the MFI-measurement of the 3D-printed filaments that does not require special laboratory equipment (plastometers). [ABSTRACT FROM AUTHOR]

Highlights The increasing production of plastics and its resulting environmental problems and waste management issues have prompted stakeholders and communities to focus on reducing, recycling, and reusing plastic products at the industrial level. While many important initiatives have been launched with a circular economy perspective, there is still a lack of research on the mechanical properties of various mixtures of recycled plastics. To address this research gap, the primary objective of this study is to present a parametric investigation on the homogenization of four different types of plastics: virgin polypropylene, recycled polypropylene, recycled high‐density polyethylene, and recycled low‐density polyethylene. The study aims to develop a homogenization methodology for multimaterial plastics reinforced with carbon nanotubes, focusing on their mechanical behavior, especially the Young's modulus. The second section of the research focuses on studying the Melt Flow Index (MFI) of various mixtures of recycled plastics. By analyzing the MFI, valuable insights can be gained regarding the flow characteristics and processability of these plastic blends. Finally, the research investigates the incorporation of nanoparticles into these novel polymers to enhance their mechanical properties, with a specific emphasis on addressing the reduction in Young's modulus caused by the utilization of recycled plastics. Overall, this study aims to contribute to the understanding of the mechanical behavior and processing characteristics of recycled plastic mixtures, as well as exploring potential strategies for improving their properties through the incorporation of nanoparticles. Mechanical and processing properties of Plastic blends are not studied yet. Proposing parametrical homogenization formulas to predict such properties. Mechanical properties obtained are low and not suitable for structural purposes Adding to the blend carbon nanotubes to increase their properties. Properties are increased up to 11 times for recycled plastics blend. [ABSTRACT FROM AUTHOR]

The effect of γ-irradiation on the surface properties of polypropylene (PP) has been studied as a function of the absorbed dose. It has been established that γ-irradiation leads to an increase in the free surface energy of the polymer, its acid–base component, and the surface polarity. An analysis of the IR spectra of γ-irradiated PP samples indicated the formation of oxygen-containing groups in the composition of PP macromolecules, which was confirmed by the values of the surface acidity parameter. An increase in the dose led to an increase in the concentration of products of radiation-induced conversion. A significant increase in the melt flow index (MFI) of polypropylene up to an absorbed dose of 150 kGy also evidenced the occurrence of oxidation and destruction processes. The MFI decreased at radiation doses above 150 kGy, and this fact indicates that such doses of ionizing radiation lead to the predominance of the processes of polymer structuring or crosslinking. [ABSTRACT FROM AUTHOR]

Pyrolytic gas chromatography and X-ray photoelectron spectroscopy were used to analyze the stability of bridging groups in polyether ether ketone (PEEK) at temperatures of 400–650 °C and bombardment with argon ions of various energies and intensities. Both thermal and ionic exposures lead to the destruction of bridging C=O groups and ether C—O—C bond between the aromatic rings of PEEK. [ABSTRACT FROM AUTHOR]

The presence of impurities such as H2S, thiols, ketones, and permanent gases in propylene of fossil origin and their use in the polypropylene production process affect the efficiency of the synthesis and the mechanical properties of the polymer and generate millions of losses worldwide. This creates an urgent need to know the families of inhibitors and their concentration levels. This article uses ethylene green to synthesize an ethylene–propylene copolymer. It describes the impact of trace impurities of furan in ethylene green and how this furan influences the loss of properties such as thermal and mechanical properties of the random copolymer. For the development of the investigation, 12 runs were carried out, each in triplicate. The results show an evident influence of furan on the productivity of the Ziegler–Natta catalyst (ZN); productivity losses of 10, 20, and 41% were obtained for the copolymers synthesized with ethylene rich in 6, 12, and 25 ppm of furan, respectively. PP0 (without furan) did not present losses. Likewise, as the concentration of furan increased, it was observed that the melt flow index (MFI), thermal (TGA), and mechanical properties (tensile, bending, and impact) decreased significantly. Therefore, it can be affirmed that furan should be a substance to be controlled in the purification processes of green ethylene. [ABSTRACT FROM AUTHOR]

The effect of extrusion parameters on the characteristics of nanocomposites based on polypropylene random copolymer and ethylene–propylene block copolymer with carbon black and aluminum nanoparticles and calcium stearate was studied. Printex XE 2-B carbon black with the nanoparticle size of 18–20 nm was used. Exхelor PO 1020 compatibilizer was used for improving the compatibility of the blend components. Introduction of the above fillers allows obtaining a multifunctional nanocomposite that exhibits high levels of electrical conductivity, adhesion to metals, and thermal conductivity and can be processed by pressure casting and extrusion. The effect of the temperature conditions in the extruder material cylinder on the breaking stress and relative elongation of the nanocomposites was considered. The optimum temperature conditions of the extrusion, ensuring relatively high properties of the composite, were determined. [ABSTRACT FROM AUTHOR]

Polymer 3D printing has motivated researchers toward the use of this technology for the maintenance and repair of heritage structures. This results in the exploration of different thermoplastic composites as smart materials having properties like programmable features (one-way, two-way), sensing, etc. Also, the excessive use of thermoplastics in various fields has resulted in plastic solid waste management issues. Several studies have been reported on plastic solid waste management with 3D printing. But hitherto little has been reported on the use of heritage site debris as reinforcement in the thermoplastic matrix for addressing issues of plastic solid waste management as well as for inducing controlled 4D capabilities; for better maintenance and repair of the heritage site with shorter maintenance and repair time. The present study is focused on secondary (2˚) recycling of polyvinylidene fluoride thermoplastic material by reinforcing limestone (CaCO3 of 220 mesh size as per American Foundry Society (AFS)) collected as debris from heritage site for 3D printing applications followed by an analysis of its possible 4D capabilities. Different compositions/proportions of polyvinylidene fluoride–limestone were explored for acceptable rheological (melt flow index and viscosity), thermal (based on differential scanning calorimetry), mechanical (based on universal testing machine), and spectroscopic properties (based on attenuated total reflection-Fourier transformed infrared and photoluminescence). Piezoelectric property analysis of 3D printable composition/proportion and shape-memory effect of each composition/proportion was performed to investigate the 4D characteristics of the proposed composite. The results of the study suggest that polyvinylidene fluoride–6% limestone is a better composition/ proportion with acceptable rheological, thermal, and mechanical properties (melt flow index 2.429 g/10 min, viscosity 12742.9 Pa-s, thermal heat capacity 31.66 Jg−1, and Young's modulus 286.56 MPa) for selected heritage structures. For 4D capabilities, piezoelectric coefficient (D33 21.79 pC/N) and shape recovery (44.31%) have been ascertained for the best composition/ proportion selected. Further morphological analysis has been reported to support the test results. [ABSTRACT FROM AUTHOR]

In this study, the polymeric membranes were prepared using discarded polyethylene terephthalate (PET) bottles. The fabrication of the membrane process was carried out using a dope solution composed of polyethylene terephthalate (polymer), O-cresol (as a solvent), and polyethylene glycol 400 (as an additive). The solubility parameters were studied to dissolve the polymer into the solvent at a specific temperature. The melt flow index and thermal analysis were evaluated for the discarded bottles and prepared membranes to ensure the quality and thermal stability of the PET. The porosity of the membranes was determined using scanning electron microscopy. The temperature required to prepare the dope solution was 80 °C with a stirring speed of 350 rpm. Non-solvent-induced phase separation method was used to fabricate the membranes. The coagulation bath was composed of a water–ethanol mixture. The porosity of the prepared membranes ranges between 30 and 50%. The contact angle was determined for the membrane in the range of 40° to 80°. The flux of the membranes was evaluated using membrane testing cell at a specified pressure which ranges from 80 to 150 Lm−2 h−1. The prepared membranes could be used in various industries like dairy, pharmaceutical, juice, and beverages to separate temperature-sensitive substances. [ABSTRACT FROM AUTHOR]

The paper presents the results of a study of the effect of nitrile butadiene elastomer content on the main physical-mechanical properties of high density polyethylene based compositions. Properties such as tensile yield strength, ultimate tensile stress, elongation at break, flexural strength, thermal stability, and melt flow rate were investigated. To improve the compatibility of the mixed components, a compatibilizer was used, which is a graft copolymer of high-density polyethylene with methacrylic acid. The amount of compatibilizer in the mixture was 3.0 wt%. The concentration of the elastomer in the composition varied from 10 to 50 wt%. Elastomers containing 18, 26, and 40 wt% acrylic acid nitrile (SKN-18, SKN-26, and SKN-40) were used as nitrile butadiene elastomers. It was found that the transition from plastic strain to highly elastic for the high density polyethylene-based composite with SKN-18 starts at 30 wt% content of the elastomeric component. For compositions of high density polyethylene with SKN-26 and SKN-40, this transition occurs at 40 wt% content of the elastomeric component. The influence of the concentration of dicumyl peroxide on the regularities of changes in the properties of these compounds was also studied. It was found that the optimal concentration of the peroxide initiator is 0.5 wt%. The results of the study of electron microscopic analysis and thermomechanical characteristics of mechanical mixtures and dynamically vulcanized elastoplastics were presented, which allow obtaining additional information about the structural features and deformation characteristics of cross-linked polymeric materials. [ABSTRACT FROM AUTHOR]

In the past decade, some studies have been reported on the 3D printing of energy storage devices (ESD) by using recycled thermoplastics (such as acrylonitrile–butadiene–styrene (ABS), polyamide, etc.) through fused deposition modeling (FDM). But hitherto little has been reported on the development of recyclable and flame retardant ESD (by using recycled thermoplastics and thermosetting composite). In this work, efforts were made to 3D print ESD with flame retardant capabilities on FDM by using an ABS-melamine formaldehyde (C4H8N6O) (ABSM) based composite matrix. The components of ESD were prepared in four sections/segments. Three sections were: 3D printed ABSM-based composites reinforced with graphite (Gr), MnO2, and electrolyte (NH4Cl + ZnCl2), and the fourth section was of Zn cast plate. The functional prototype as ESD has been prepared by assembling these four sections. Final observations are supported based upon thermal, mechanical, morphological, flame retardant, V-I, and V-R characterization. [ABSTRACT FROM AUTHOR]

Fused Deposition Modeling (FDM) is one of the most efficient and frequently used methods for the development of biomedical implants, bio-sensors, and customized products. In the FDM process, the filament made of polymers or composites is passed through a nozzle in which heaters are provided to melt the feedstock filament. The addition of copper particles to the polymer filament would enhance its thermal and electrical conductivity which finds vast applications in the development of sensors and other electronic components. Thus, it is obligatory to maintain the melt flow index of the filament following the size of the nozzle and the speed of the filament through the nozzle. The virgin polymer materials used as feedstock filament have an appropriate melt flow index (MFI), but the rheological properties of the polymer composites are not defined. This study focuses on the calculation and measurement of the melt flow rate of copper reinforced with acrylonitrile butadiene styrene (ABS) and nylon 6 thermoplastic matrices using fused deposition modeling. The copper particles of different sizes (149 μm, 74 μm, and 37 μm) were added in ABS and nylon 6 thermoplastic matrices to study the mechanical properties. The melt flow rate has been checked for different concentration ratios varying from 1% to 10% of copper reinforcements. The impact of single, double, and triple-sized copper particles on MFI has been investigated. It has been found that with an increase in copper powder concentration in nylon 6, the melt flow index decreases. On the other hand, the MFI initially increases up to 6% and further decreases by adding more particulates of copper powder in ABS. The surface topography of copper reinforced with different percent-compositions of ABS and nylon 6 based polymer composites have been carried out by using scanning electron microscopy. [ABSTRACT FROM AUTHOR]

In past decades, several studies have been reported on the fabrication of thermoplastic matrix-based filaments by mechanical blending with a twin-screw extruder (TSE) for 3D printing applications. But hitherto little has been reported on the chemical-assisted mechanical blending of secondary (2°) recycled acrylonitrile butadiene styrene (ABS) matrix with reinforcement of wood dust (WD) and bakelite powder (BP) for non-structural engineering applications. This study demonstrates the influence of TSE processing parameters on various properties (mechanical, rheological, and thermal) of composite filaments prepared by reinforcing WD and BP in a 2° recycled ABS matrix with the assistance of a chemical (acetone) as a novel fabrication technique. It was observed that chemical blending of reinforcements in ABS resulted in improved mechanical properties as compared to mechanical blending, however, the heat-carrying capacity of filaments with chemical assisted blending was degraded. The enhanced peak strength (PS) along with percentage break elongation (%BE) of ABS+BP-based composite filament was observed at 10 kg (load), 245°C (temperature) and 70 rpm (speed) with the corresponding values of PS and %BE as (30.93 MPa, 5.43%), respectively. The input parameters (10 kg, 225°C, 70 rpm) displayed optimum PS and %BE (35.72 MPa, 6.87%), respectively, for ABS+WD-based composite filaments. [ABSTRACT FROM AUTHOR]

The study focused on the evaluation of the influence of inhibitory compounds such as hydrogen sulfide (H2S) and methanol (CH3OH) on the catalytic productivity and properties of the polymers in the polymerization process with the Ziegler–Natta catalyst. The investigation involved experimental measurements, computational calculations using DFT, and analysis of various parameters, such as molecular weight, melt flow index, xylene solubility, and reactivity descriptors. The results revealed a clear correlation between the concentration of H2S and methanol and the parameters evaluated. Increasing the H2S concentrations, on average by 0.5 and 1.0 ppm, resulted in a drastic decrease in the polymer’s molecular weight. A directly proportional relationship was observed between the flow rate and the H2S concentration. In the case of methanol, the change occurred from 60 ppm, causing a sharp decrease in the molecular weight of the polymer, which translates into an increase in the fluidity index and a decrease in solubility in xylene. The presence of these inhibitors also affected the catalytic activity, causing a reduction in the productivity of the Ziegler–Natta catalyst. Computational calculations provided a deeper understanding of the molecular behavior and reactivity of the studied compounds. The computational calculations yielded significantly lower results compared to other studies, with values of −69.0 and −43.9 kcal/mol for the Ti-CH3OH and H2S interactions, respectively. These results indicate remarkable stability in the studied interactions and suggest that both adsorptions are highly favorable.

The primary (1°) recycled acrylonitrile butadiene styrene (ABS) is one of the most acceptable thermoplastic for 3D printing applications. For ascertaining rheological and dimensional features of 3D printed functional prototypes, one must have control on feed stock filament volume and its melt flow index (MFI). Some studies have reported investigations on mechanical and thermal properties along with dimensional features and MFI of 1° recycled ABS. But hitherto little has been reported on effect of cryogenic milling (CM) on rheological, morphological, and surface properties of feed stock filament (for possible 3D printing). This article reports the effect of CM on 1° recycled ABS for 3D printing applications. The effects of CM input parameters such as vibration frequency (Hz), CM time (min), and weight of grinding media (g) have been investigated for rheological (MFI, sample volume), surface (Shore D hardness, porosity), and morphological (based upon photomicrographs) properties. Based upon analysis of variance for sample volume and MFI of the 1° recycled ABS, grinding frequency was observed as most significant factor (91.88% for sample volume and 76.59% for MFI) at 95% confidence level in the present case study. The results of study suggest that sample volume and MFI observations are in line with Shore D hardness and porosity. [ABSTRACT FROM AUTHOR]

Ultra-high molecular weight polypropylene (UHMWPP), with a molecular weight of more than 106 g/mol, is expected to have superior properties, such as high mechanical strength, high thermal properties, high chemical resistance and outstanding tribological properties. However, UHMWPP has a very poor processability due to its high melt viscosity. Therefore, we aimed to improve processability of UHMWPP by blending it with a low molecular weight polypropylene (LMWPP). We attempted to improve the interfacial miscibility and intermolecular entanglement of the UHMWPP/LMWPP system by using a kneader machine. The addition of LMWPP tended to change the mechanical, thermal, and rheological properties of the blend system. [ABSTRACT FROM AUTHOR]

Thermoplastic elastomers, such as styrene–butadiene–styrene (SBS), significantly enhance the properties of asphalt binders. This study first highlights the drawbacks of binder modification using chemically grafted polyethylene (g-PE) and then demonstrates the process by which g-PE can be used in combination with SBS. The important role of chemical grafting, sulphur content, and melt flow index (MFI) value in obtaining practically usable 'g-PE/SBS' modified binders have been illustrated. The results show that ungrafted and g-PE produces modified binders with highly inferior properties, and the polymers phase separate from the binder within few hours of preparation. % Elastic recovery of the ungrafted and g-PE modified binders was < 30%, and the softening point was 10 to 25 °C lower than SBS modified binders. Modification using the '50/50' g-PE/SBS blend also resulted in inferior modified binders. On the other hand, the '25/75' g-PE/SBS blend resulted in modified binders with properties similar to SBS modified binders. Chemical grafting, sulphur content of 0.21 wt.%, and melt flow index value > 2 are the essential factors that resulted in acceptable '25/75' g-PE/SBS modified binders. Cost analysis shows that the use of g-PE can reduce the overall cost of asphalt pavement. The strategy illustrated in this study can be adopted for low-cost polymers and the effective utilization of waste plastics. [ABSTRACT FROM AUTHOR]

A procedure was developed for preparing polyphenylene sulfide with low melt viscosity by liquid-phase polycondensation at pH > 12 with stepwise heating from 160 to 220°С in the prepolycondensation step and from 230 to 260°С in the afterpolycondensation step. The polyphenylene sulfide melt flow index can be varied from 300 to 18 g/10 min by stepwise variation of the Na2S excess and temperature in the course of polyphenylene sulfide polycondensation. The optimum time of the polyphenylene sulfide synthesis was 16 h. The polyphenylene sulfide exhibits the physicomechanical properties similar to those of Ryton@ XE5500BL thermoplastic (Solvay) but is characterized by 50% lower water absorption. [ABSTRACT FROM AUTHOR]

In the past decade, the use of secondary (2°) recycled polymers (such as polyvinylidene fluoride (PVDF) and polyurethane) has been explored for smart engineering applications such as self-healing, self-expanding, and contracting. But hitherto little has been reported on the use of tertiary (3°) recycled polymers for such applications. In this work, 2° and 3° recycled PVDF-based thermoplastic composites have been compared to establish a suitable recycling process for 3D-/4D-printing applications in the repair of heritage structures. The 3° recycled composite matrix was prepared by chemical-assisted mechanical blending (CAMB) also known as solution blending of PVDF and CaCO3. The rheological, thermal, mechanical, bonding, morphological, and piezoelectric properties of prepared composites were compared with composite prepared by 2° recycling (mechanical melt blending). Further chemical treatment (as a stimulus) was performed to investigate the effect on the one-way programming of the composite. The results of the study outlined that CAMB is more suitable than mechanical melt blending as a material processing route for PVDF–CaCO3 composite with acceptable one-way programming features. In this study, the rheological, thermal, mechanical, and piezoelectric properties of 3° recycled composite were observed better than those of 2° recycled composite. Further, the observations from morphological (scattered scanning microscopy—energy-dispersive spectroscopy), bonding characteristics (x-ray diffraction, Fourier transform infrared spectroscopy), magnetic properties (vibration sample magnetometry), and photoluminescence analyses of the composite supported the outcome. [ABSTRACT FROM AUTHOR]

Poly(propylene carbonate phthalate) (PPC-P) is a chemically modified poly(propylene carbonate) (PPC) biodegradable thermoplastic by introducing phthalic anhydride (PA) as the third monomer into the copolymerization of propylene oxide (PO) and CO2. To enhance the thermal and mechanical properties of PPC-P, a branching agent pyromellitic anhydride (PMDA) was introduced into the terpolymerization of PO, PA and CO2. The resulting copolymers with branched structure, named branched PPC-P, can be obtained using metal-free Lewis pair consisting of triethyl borane (TEB) and bis(triphenylphosphine)iminium chloride (PPNCl) as catalyst. The products obtained were analyzed by NMR spectroscopy and their thermal, mechanical properties and melt processability were evaluated by DSC, TGA, tensile test and melt flow index (MFI) measurement. The obtained branched PPC-P has a high molecular weight up to 156.0 kg·mol−1. It shows an increased glass transition temperature (Tg) higher than 50 °C and an enhanced tensile strength as high as 38.9 MPa. Noteworthily, the MFI value decreases obviously, indicative of an improved melt strength arising from the branched structure and high molecular weight. What is more, the branched PPC-P exhibits reasonable biodegradability, which demonstrates the great potential as a new green thermoplastic for the family of biodegradable plastics. [ABSTRACT FROM AUTHOR]

For recycling purposes, the thermal degradation of post-consumed (pc) ABS/HIPS and PP/PE blends derived from waste electrical and electronic equipment (WEEE) was obtained by multiple extrusions. The evolution of molar mass (Mw), melt flow index (MFI), and ultimate elongation (εr) of reprocessed blends was evaluated as a function of extrusion cycles. The degradation mechanism of ABS/HIPS blends corresponds to a random chain scission as indicated by a diminution of εr correlated to an increase in MFI and decrease in Mw after 30 cycles of extrusion. The same type of degradation mechanism occurs on the PP/PE blend as shown by the drop in Mw and thus an increase in MFI by a factor of six but only after 11 cycles, thus suggesting the higher thermomechanical resistance of ABS/HIPS. The beginning of the critical molar mass for embrittlement (M'c) zone was reached around 130 and 200 kg/mol for ABS/HIPS and PP/PE, respectively, which can be related to the beginning of the critical MFI zone around 12 and 63 g/10 min (230 °C/2.06 kg), respectively. As a result, we propose an innovative embrittlement criterion using MFI measurements that allow a quick and easy analysis of post-consumed polymer blends.

Polyvinyl chloride compositions are widely used to obtain various types of products. In the composition of the PVC composite, one of the main ingredients is a plasticizer, the introduction of which makes it possible to vary the characteristics of the obtained polymeric materials and products and significantly expand the range of their application. Manufacturability in the processing of polyvinyl chloride compositions serves as an important criterion for the suitability and economic efficiency of the developed plasticizer. In the modern world, the high quality of products is directly related to their environmental safety. In this regard, the work describes the production of environmentally friendly plasticizers based on adipic acid and ethoxylated butanol. Their physicochemical indicators have been investigated. The effect of the obtained additives on the rheology of PVC composites has been studied. The values of the flow characteristics of the melts of the developed PVC compositions plasticized with butyl butoxyethyl adipate and decyl butoxyethyl adipate were estimated. It was shown that the fluidity of melts, in comparison with compounds of a similar composition containing industrial dioctyl phthalate, is characterized by even slightly higher values. [ABSTRACT FROM AUTHOR]

Among various nanomaterials used for food packaging, zinc oxide (ZnO) nanoparticles are one of the best choices due to their high antimicrobial property. However, for biodegradable materials like poly(butylene adipate-co-terephthalate) (PBAT), biodegradability can be limited by the antibacterial function. Thus, in the present study, reinforced PBAT films with different weight percentages (1, 3, and 5 wt%) of ZnO nanoparticles were prepared by the casting process to investigate the effects of ZnO on the thermostability, mechanical, and antimicrobial properties of the PBAT film. The results showed that the small amount of ZnO (1 wt%) reduced the decomposition temperature of the PBAT film by nearly 50 °C, and the thermal stability was significantly decreased with the increasing ZnO content. Melt flow index comparison showed that the ZnO nanoparticles accelerated the room temperature degradation rate of PBAT films. In addition, due to the degradation effect of ZnO nanoparticles, the mechanical properties such as the total percentage of elongation (at break), the tensile strength, and yield strength decreased with the addition of ZnO nanoparticles. The antibacterial test showed that PBAT + 1 wt% ZnO films could achieve high antibacterial activity (R = 6.8) against Escherichia coli. This study is important for controlling the degradation period of biodegradable materials. [ABSTRACT FROM AUTHOR]

This work focuses on studying the influence of coupling agents on the degradation in the mechanical properties of Polypropylene (PP)/wood composites. Maleic anhydride polypropylene (MAPP) was used as a coupling agent between the wood flour and PP matrix. As the coupling agent plays an important role in the stability of the WPC, a 10 wt% wood flour was mixed with PP granules along with a UV stabilizer and varying percentages (1, 3, 5 wt%) of MAPP in a twin-screw extruder to obtain PWC granules. The composite granules were injection molded to produce tensile samples for the mechanical characterization of the composites. To test the environmental degradation of the PWCs, the tensile samples were exposed to the environmental conditions for 0, 336 h (14 days), and 672 h (28 days) prior to testing. After the specified exposure time, the samples were mechanically characterized using tensile testing. The degradation characteristics of the WPCs were quantified in terms of the failure strains of the composite with exposure time. The experiments were designed, and various analyses, including ANOVA, regression equation, and prediction tests, were carried out to investigate the impact of parameters on the failure strain of the PWCs. Moreover, the study aimed to examine the effect of parameters such as MAPP and time, on the failure strain of the composites. From the experimental results, it is concluded that the composites containing 1 wt% of MAPP showed superior retention in the degradation of composites when compared with 3 and 5 wt% MAPP content., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests., (© 2024 Published by Elsevier Ltd.)

The recycling of plastic waste is undergoing fast growth due to environmental, health and economic issues, and several blends of post-consumer and post-industrial polymeric materials have been characterized in recent years. However, most of these researches have focused on plastic containers and packaging, neglecting hard plastic waste. This study provides the first experimental characterization of different blends of hard plastic waste and virgin polypropylene in terms of melt index, differential scan calorimetry (DSC), thermogravimetric analysis (TGA), mechanical properties (tensile, impact and Shore hardness) and Vicat softening test. Compared to blends based on packaging plastic waste, significant differences were observed in terms of melt flow index (about 10 points higher for hard plastic waste). Mechanical properties, in particular yield strain, were instead quite similar (between 5 and 9%), despite a higher standard deviation being observed, up to 10%, probably due to incomplete homogenization. Results demonstrate that these worse performances could be mainly attributed to the presence of different additives, as well as to the presence of impurities or traces of other polymers, other than incomplete homogenization. On the other hand, acceptable results were obtained for selected blends; the optimal blending ratio was identified as 78% post-consumer waste and 22% post-industrial waste, meeting the requirement for injection molding and thermoforming. [ABSTRACT FROM AUTHOR]

This study deals with the friction stir welding of 3D printed thermoplastic composites. In this study, the electrolytic Al metal particulate reinforced with the acrylonitrile butadiene styrene (ABS) and polyamide 6 (PA6) with 15% and 50% weight proportion respectively confirmed the feasibility of joining. Investigations have been made on welded joints prepared with consumable friction stir welding tool on 3D printed functional prototypes of ABS-15Al and PA6-50Al thermoplastic composites (for optimizing mechanical, morphological, and thermal properties). The online monitoring of temperature and friction stir welding (through thermal imaging camera) and axial force measurement (based upon milling dynamometer) has been made to understand the mechanism/changes in the mechanical, morphological, and thermal properties. Overall, best mechanical properties were observed at 1400 r/min, 50 mm/min feed rate, and 4 mm consumable plunge depth. [ABSTRACT FROM AUTHOR]

In Part I of this two‐part series the most important aspects of antioxidants (primary and secondary), processing aids, metal deactivators and some light stabilizers were described and highlighted together with their mechanisms, problems, and interactions. Emphasis was placed on synergism and antagonism in performances and color problems with a special insight regarding PVC. Part 2 of this article presents in a similar way general perspective on the type, mode of action, properties, uses, problems (and circumvention) of light stabilizers and of some important fillers and pigments. Montmorillonites, silica, carbon blacks, and titanium dioxide will be the main features with an emphasis on structure, activity, and formulations in polymer systems. Additive interactions between stabilizers and fillers/pigments is a major controlling factor in the end use performance from a physical, esthetic, structural, mechanical, and chemical point of view. Indeed, with filled polymers one enters an overly complex world of interactions giving rise to some extreme synergistic and often antagonistic problems which can in many cases destroy or even enhance the activity of functional processing additives. Several of these will be highlighted to provide the technologist with at least some experience such that one can be alert to any potential issues in formulating more complex packages where not just color but high performance is also required. [ABSTRACT FROM AUTHOR]

The article presents an original technique that does not require the use of specialized laboratory equipment for measuring the melt flow rate of a composite filament obtained as a result of bulk modification of the polyethylene terephthalate glycol matrix with shungite and molybdenum disulfide. In the empirical study of the rheological properties of the formed polymer composites, it was found that the rate of filament extrusion through the nozzle (∼∅500 μm) FFF (Fused Filament Fabrication) of a 3D printer (Anycubic Mega S) differs significantly from the values of the melt flow index (MFI) measured using an industrial plastometer (IIRT-5). The obtained results must be taken into account when slicing stereolithography (STL) models for the directed control of 3D models extrusion parameters in software's (Cura, Simplify3D or others) to improve the quality of 3D printed products. • A new technique for measuring the melt flow rate of a composite filament is proposed. • Results must be taken into account when slicing STL-models for the directed control of extrusion parameters in software's. • Transformed: Simulation and experiment shows synergistic effect of the bulk and surface modification by the fluorination of PETG-filament. [ABSTRACT FROM AUTHOR]

Polyvinyl chloride (PVC) is used to obtain a wide range of materials for various purposes. High demand of PVC is explained by possibility to modify polyvinyl chloride and produce broad range of materials with improved properties as well as to have cost efficient ratio: productivity, available raw materials, saving of natural resources. However, under normal temperature polyvinyl chloride is brittle and inelastic, that limits the fields of PVC application. The production of basic PVC compositions is impossible without plasticizers – low-molecular compounds that allow direct regulating physical and mechanical properties of polymer. Production of plasticizers became one of the most important branch of petrochemical industry. Recently, however, the range and production of plasticizers have drastically decreased due to the increased cost, which reduced the competitiveness of plasticized PVC products. Therefore, the expansion of plasticizer variety for PVC is a strategic task of great practical significance. The present work describes synthesis methods of esters on the basis of oxyalkylated alcohols suggested as polyvinyl chloride plasticizers. Physico-chemical properties of synthesized compounds were studied. Conditions for their production with maximum outcome were selected. The results of experiments in which obtained compounds were tested as additives in the plasticization of PVC showed that the obtained samples of cable plastic, adhesive PVC tapes and multi-layered polyvinyl chloride linoleum satisfy all the technical requirements by the main indicators: cable plastic compound – GOST 5960-72 with amendment 1-9; a PVC adhesive tape – Technical Conditions – 2245-001-00203312-2003; multilayered linoleum – GOST 7251-77. According to the experimental results, phthalates of oxyalkylated alcohols possess rather high efficiency as plasticizers of polyvinyl chloride and are recommended for use in the above-mentioned industrial PVC recipes

In this study, the changes in mechanical, rheological and morphological properties of glass-fiber reinforced poly(oxymethylene) composite after ageing were investigated. Samples were prepared with plastic injection molding method. Ageing process was done by waiting samples at laboratory temperature and water during 28 days. Tensile and 3 point flexural tests were done to determine the mechanical properties, melt flow index (MFI) was measured to determine the rheological property and scanning electron microscopy (SEM) was used to observe the morphological structure. From experimental results, it was seen that mechanical, rheological and morphological properties were affected by the ageing environment. It was found that mechanical properties of aged samples were lower than that of unaged sample. The most decrement in the mechanical properties was occurred at the aged in water samples. Ageing process increased MFI value.