Abstract Epoxy-based composites reinforced with natural fibers and particulate fillers are gaining attention as sustainable alternatives to metallic components. This study investigates tamarind fiber–epoxy composites enhanced with silica (SiO 2 ) and tamarind fruit seed (TS) particles to evaluate their mechanical, and water absorption properties. Composites were fabricated by the hand lay-up process, and their tensile, flexural, impact, and hardness properties were systematically analyzed. The ET (70:30) composition showed superior baseline performance, achieving tensile, flexural, and impact strengths of 56 MPa, 65 MPa, and 12 kJ/m 2 , respectively, with minimal water absorption (15 %). Reinforcement with 3 wt% SiO 2 further improved performance, yielding the highest tensile (67 MPa), flexural (77 MPa), and impact (18 kJ/m 2 ) strengths, along with reduced water absorption (10 %). SiO 2 proved more effective than TS due to its higher stiffness, barrier properties, and interfacial compatibility with the epoxy matrix. These results demonstrate that SiO 2 -reinforced ET (70:30) composites offer excellent strength, toughness, and moisture resistance, making them promising candidates for engineering applications such as automotive components, structural panels, and moisture-prone environments.
Abstract Polyimides (PIs) have been attracting increased attention due to their unique advantages, such as excellent thermal stability, good mechanical properties and low dielectric constants. However, poor solubility hinders their further application. To solve this problem, a series of PIs with different side units (–CH 3 , –CF 3 and –COOH) were synthesized, and the relationship between molecular structure and solubility was thoroughly investigated. In general, solubility has been significantly improved, and all the polymers could be dissolved in hot m-cresol and N-methylpyrrolidone (NMP). With increasing polarity of side units (–COOH > –CF 3 > –CH 3 ), the solubility of their corresponding polymers (PI-COOH, PI-CF 3 and PI-CH 3 ) improved, and PI-COOH could be dissolved in alkaline aqueous solutions. In addition, PI-COOH films showed an outstanding comprehensive performance with a high tensile strength greater than 100 MPa, a high initial decomposition temperature of 420.3 °C, a low coefficient of thermal expansion (CTE) of 9.62 ppm °C −1 and a low dielectric constant of less than 3. PI-COOH also possessed a good charring capacity, and a char yield of 40 % was achieved at a high temperature of 800 °C. Due to characteristics such as solubility in alkaline aqueous solutions, high mechanical properties and good charring capacity, when PI-COOH was added to the poly(vinyl alcohol) (PVA) matrix combined with l -aspartic acid phosphate ionic liquid (ILA), the PVA composite film passed the VTM-0 test and the limiting oxygen index increased from 18.9 % to 29.3 %. Tensile strength increased by 28.3 % from 60.7 to 77.9 MPa, and elongation at break increased by 167.4 % from 95.7 % to 255.9 %. Meanwhile, the high transparency was retained.
Abstract For the high-precision fabrication of medical plastic products featuring both large aspect ratios and complex microstructures, extrusion-injection integrated molding (EIIM) has emerged as an effective manufacturing strategy. However, the interfacial bonding mechanism underlying EIIM remains insufficiently understood. In this study, a microscopic model consisting of an injection melt layer and an extruded polymer layer was established. The interfacial bonding energy of EIIM was systematically investigated. Furthermore, the molecular mean square displacement (MSD), the diffusion coefficient of the injection melt layer, and the density evolution of the overall model during the bonding process were analyzed. The simulation results demonstrate that when the stretching orientation is parallel to the bonding direction, increasing the draw ratio from 1.8 to 2.9 leads to an increase in the interfacial bonding energy, from approximately 1,000 kcal/mol to about 1,800 kcal/mol. In contrast, when the stretching orientation is perpendicular to the bonding direction, the draw ratio exhibits a negligible effect on the interfacial bonding energy. Notably, the interfacial bonding energy in the perpendicular orientation is consistently higher than that in the parallel orientation. This difference is mainly attributed to the orientation-dependent interfacial chain arrangement: chains parallel to the bonding direction can more readily penetrate the injection melt under pressure, while chains perpendicular to the bonding direction maintain a higher and relatively stable interfacial contact density, leading to consistently higher bonding energy. This work is expected to provide theoretical guidance for parameter optimization in EIIM and to offer valuable insights into the interfacial bonding mechanisms of other polymer integrated molding processes.
Abstract The inherent incompatibility between hydrophilic lignocellulosic fibers and hydrophobic thermoplastic matrices in wood-plastic composites (WPCs) creates significant interfacial bonding challenges that compromise mechanical performance and durability. This study aimed to provide a critical analysis of current trends in WPC development with particular emphasis on the effects of various binder systems on the properties of the resulting WPCs. Binders can be classified based on both chemical nature (thermoplastic, thermosetting, biopolymer, and inorganic/geopolymer) and functional mechanisms (coupling agents vs. compatibilizers), providing an extensive framework for optimal selection. Extrusion dominates industrial production due to cost-effectiveness, while injection moulding offers superior design flexibility. Mechanical property investigations confirmed that appropriate coupling agents, particularly maleated polyolefins, significantly enhance tensile strength, flexural strength, and impact resistance by bridging the compatibility gap between matrix and filler. Thermal studies demonstrated that binder selection directly influences thermal stability, with PVC-based systems showing superior heat resistance compared to polyethylene variants. Morphological analyses revealed that effective binders promote uniform filler dispersion and eliminate interfacial voids, resulting in improved stress transfer mechanisms. This study establishes a foundation for developing next-generation WPCs that balance sustainability goals with enhanced performance characteristics.
The non-biodegradability of traditional plastics poses serious environmental challenges, while the high cost of biodegradable plastics limits their widespread application. Starch, due to its abundance, low cost, and biodegradability, represents a promising alternative. However, the strong intermolecular hydrogen bonding within starch impedes its processing. To address this limitation, a novel plasticizer, 6-hydroxy-N-[2-[(2-hydroxyethyl)amino]ethyl]hexanamide (HEEHA), was synthesized to enhance the thermoplasticity of starch. Thermoplastic starch (TPS) films were fabricated by blending HEEHA with glycerol at varying ratios, maintaining a total plasticizer content of 30 wt% relative to dry starch. Their properties were characterized using FT-IR, XRD, and mechanical testing, while molecular dynamics simulations were conducted to analyze mean square displacement (MSD), radial distribution function (RDF), and hydrogen bond energy, providing insights into the underlying plasticization mechanisms. The combination of HEEHA and glycerol exhibited synergistic effects, achieving optimal performance at a 10 wt% HEEHA/20 wt% glycerol ratio, where both tensile strength and elongation at break surpassed those of single-plasticizer systems. Simulations further revealed that, at this ratio, the plasticizers displayed the highest diffusion coefficients, the most uniform spatial distribution, and the strongest hydrogen bonding interactions. The resulting TPS retained moderate starch crystallinity, contributing to enhanced mechanical properties.
This study addresses the critical challenges of high melt viscosity and matrix brittleness in pultruded continuous glass fiber reinforced polyamide 6 (GF/PA6) composites. A synergistic modification strategy combining a hyperbranched polymer (HBP) flow modifier and a reactive elastomer (POE-g-MAH) was developed to optimize the "process-structure-property" relationship. Results indicate that at a high fiber loading (36 bundles), the addition of 3 phr HBP significantly reduced porosity to 0.49 % and enhanced flexural strength to 928.4 MPa through a "ball-bearing" effect and heterogeneous nucleation. Furthermore, the incorporation of 4 phr POE-g-MAH achieved an optimal stiffness-toughness balance. In-situ interfacial reactions formed stable imide linkages, increasing notched impact strength by 18.6 % while maintaining a high flexural strength of 836.6 MPa. This multi-scale co-design strategy effectively overcomes the trade-off between impregnation quality and mechanical toughening, providing a theoretical framework for manufacturing high-performance thermoplastic pultruded profiles.
The rising prevalence of diseases such as cancer, obesity, diabetes and inflammatory bowel has become a significant public health concern due to its long-term health implications worldwide. Current strategies being deployed for the treatment process are rather nonspecific and have several side effects. There is great need to find safe and alternate strategies for the prevention and treatment of diseases. Pectin, a complex plant-derived polysaccharide primarily composed of galacturonic acid, has garnered significant attention for its versatile applications in the food, pharmaceutical, and biomedical industries. This review provides a comprehensive overview of pectin, with a particular focus on low methylated modified pectin (MP). Various plant sources of pectin are discussed, highlighting waste valorization opportunities, particularly from citrus peels and other fruit by-products. The paper delves into the structural characteristics and physicochemical properties that underpin its functionality. Special emphasis is placed on the role of MP in gut health, including its fermentation by gut microbiota into short-chain fatty acids. It also explores the various sources, extraction from conventional acid to emerging green methods, physio-chemical properties and application of modified pectin.
The influence of waste rubber on the thermal stability and mechanical properties of polyamide 12 and its nanocomposites is investigated. Organically modified montmorillonite (OMMT), ethylene-propylene diene monomer (EPDM, also referred to as waste rubber), and a polyamide 12 matrix with low melting viscosity and low water absorption are used in this study. The goal is to reduce the amount of scrap rubber in stockpiles for environmental safety. The mechanical test results indicate that higher wt% EPDM to functions as stress concentrator, demonstrating that increased EPDM content diminishes strength and ductility, suggesting inadequate interfacial bonding or particle agglomeration. The incorporation of EPDM diminishes the crystallinity of all ternary composites, but stabilizes the melting point as revealed by DSC. The band at 1,146 cm-1 is due to C-N vibration, and the 1,227 cm-1 band is due to C=N stretching, thereby increasing peak intensities. These peaks appeared when EPDM was injected into the binary nanocomposites, suggesting that it was evenly distributed throughout the PA12/OMMT nanocomposite. The study also found that adding EPDM to PA12/OMMT increases viscosity. However, the Young's modulus decreased in all cases except for the ternary nanocomposite containing 10 % EPDM.
In response to the challenges of the traditional PET industrial fiber development process, where production parameters typically require extensive trial and error and performance testing, leading to prolonged development cycles and difficulties in applying mathematical modeling for process simulations, a data-driven artificial intelligence (AI) strategy for process parameters configuration based on real production processes of PET industrial fibers is introduced. By utilizing a residual neural network, production process parameters are precisely configured according to the property indicators of PET industrial fiber, achieving a configuration determination coefficient (R-2) of 0.98. Further optimization of these parameters using a particle swarm optimization algorithm results in an R-2 value exceeding 0.99. This approach circumvents complex mathematical modeling, enabling rapid configuration of process parameters through a data-driven AI algorithm based on product property indicators, thus significantly reducing the development cycle and cost of PET industrial fibers.
Determining optimal filling conditions in injection molding is essential for ensuring part quality and process stability. Despite the variety of existing approaches, this task remains difficult when the available process information is limited or difficult to obtain. Alternatively, this work presents a simple data-driven optimization strategy based on the combination of multivariable regression (MVR) and a genetic algorithm (GA). This scheme is implemented to predict processing conditions leading to complete cavity filling using only a reduced set of experimental data obtained under short-shot conditions. The case studied is a flat-plate geometry having a hot weld line in the mid plane. Specifically, second-order MVR models were trained to quantify the influence of the most relevant processing variables during the filling stage on two complementary filling indicators: part weight and projected area. Once fitted, the models were integrated into a GA-based inverse optimization scheme to search for parameter combinations that achieve complete filling targets. The parameter combinations predicted by the MVR-GA optimization scheme were experimentally validated, resulting in fully filled parts, with average deviations of approximately 2 % and 0.6 % for weight and projected area, respectively, relative to the nominal target values. The proposed framework allowed the data-efficient exploration of different practical scenarios, where modifying one or more processing parameters requires the corresponding adjustment of the remaining ones while still achieving complete filling.
Understanding how screw geometry influences melt flow and residence time is critical for optimizing single-screw extrusion, particularly for thermally sensitive polymer melts. While the effects of key geometrical parameters such as screw diameter, screw pitch, and channel depth are well-studied, the specific impact of the flight flanks on conveying efficiency remains poorly quantified. In this study, a numerical parametric study was performed using computational fluid dynamics (CFD) to investigate the conveying behavior of three extruder screws with different flank angles under various rheological and operating conditions, including both isothermal and non-isothermal flows. Key metrics included velocity distributions, the degree of stagnation, throughput, and residence time distributions (RTDs). Non-isothermal simulations additionally captured the influence of flight geometry on axial temperature development. The results demonstrate that increasing the flight flank angle streamlines melt flow, reduces stagnant regions, and slightly decreases throughput due to reduced channel volume. RTDs reveal a significant reduction in long-residence-time trajectories for streamlined screws, particularly at low screw speeds, indicating a lower risk of thermal degradation. Non-isothermal simulations show that streamlined flight geometry slightly increases melt temperature, while thermal effects further contribute to a reduction in degree of stagnation. These findings provide a qualitative and quantitative framework linking screw geometry to local and global melt transport and thermal behavior, offering guidance for the design of single-screw extruders to improve processing efficiency and product quality.
Long-chain branching (LCB) is achieved in low-density polyethylene (LDPE) via reactive extrusion using a dual-agent strategy. Trimethylolpropane trimethacrylate (TMPTMA) and dicumyl peroxide (DCP) function as a multifunctional grafting agent and free-radical initiator, respectively, and polyhexene-1 is used as a co-component to promote chain scission and enhance branching while suppressing excessive crosslinking. The incorporation of TMPTMA (2 wt%) into the LDPE backbone, verified using Fourier-transform infrared spectroscopy, results in a maximum grafting efficiency of 36.7 %. Rheological characterization reveals that the incorporation of TMPTMA significantly enhances the strain-hardening behavior, zero-shear viscosity, and shear thinning properties, indicative of LCB. Morphological analysis shows that reducing the phase domain size and improving the dispersion of the minor phase in the LDPE matrix increases interfacial compatibility. Notably, loading an excess of TMPTMA (>2 wt%) instigates homopolymerization and reduces the branching efficiency. These results demonstrate that the controlled architectural modification of polyethylene using reactive extrusion enables tailored viscoelastic behavior.
This article presents a novel Euler-Lagrange modelling framework for the dynamic analysis of single screw extruders, commonly used in polymer and food processing industries. Traditional modeling approaches often rely on empirical correlations and steady-state assumptions, limiting their accuracy in capturing transient behaviors and complex interactions within the extruder. The proposed framework leverages the principles of Euler-Lagrangian coupling mechanisms to systematically derive the governing equations for both particles and fluids. By treating the extruder as a system with coupled mechanical and thermal domains, this approach enables a more accurate and physically consistent representation of its dynamic behavior. Simulation results demonstrate the model's capability to predict transient responses and highlight its potential for use in control design, process optimization, and fault detection. This work lays the foundation for a unified and extensible modelling strategy for advanced extrusion systems.
Thermosetting molding compounds such as sheet molding compound (SMC) and bulk molding compound (BMC) are attractive alternatives to high-temperature thermoplastics and light metals for lightweight parts, but detachable joints require suitable joining methods. This work evaluates the feasibility of direct screw fastening in SMC/BMC and quantifies how boss geometry and processing parameters affect pull-out strength. Two SMC grades (electrical and car-body) were compression molded and one BMC grade was injection molded; screw bosses with systematically varied outer and core-hole diameters were produced and assembled with thread-forming/cutting screws. Quasi-static pull-out tests (n = 5) were complemented by Rubber Process Analyzer (RPA) viscosity measurements and X-ray computed tomography (CT) to relate mechanical performance to process-induced defects. Direct screwing proved feasible, reaching pull-out forces up to 2.5 kN for the electrical SMC with a 5 mm screw. The car-body SMC showed markedly lower strengths due to porous/missing material in the core-hole region, consistent with its substantially lower viscosity (RPA). For BMC, weld lines and internal cavities triggered radial cracking or boss bursting during screw insertion; increasing holding pressure and reducing volume flow mitigated defects but only modestly improved strength. Overall, load capacity is governed mainly by material-dependent viscosity effects during cavity filling rather than by mold temperature or pressure within the investigated window, highlighting the need for geometry-specific process control and application-oriented material selection for robust direct screw joints in thermosets.
This study presents a detailed numerical analysis of a centrifugal dryer in polymer pelletizing systems, focusing on the effects of rotor geometry and speed on mechanical drying performance. Employing a coupled Discrete Element Method (DEM) and Moving Particle Semi-implicit (MPS) approach to simulate particle interactions and fluid dynamics, we investigated rotor flight angles (10 degrees, 45 degrees, and 70 degrees), number of flights (10-25), and speeds (1,280, 1,600, and 920 rpm). Performance metrics included pellet discharge count, discharge time for 1,000 pellets, residence time distribution, and energy consumption. Results indicate that a 45 degrees flight angle consistently promotes stable discharge, efficient pellet transport, and narrow residence time distributions. The configuration with 45 degrees, 14 flights, and 1,280 rpm achieved the highest throughput with well-controlled residence times (1.94-6.95 s) and moderate energy use (16.21 Wh), balancing efficiency and energy consumption. In contrast, 10 degrees configurations lacked sufficient lift, while 70 degrees angles caused recirculation and particle trapping. Increasing flight count improved confinement and uniformity but led to inefficiencies at high speeds. Rotor speed improved performance up to an optimal point beyond which instability and energy loss occurred.
This study systematically investigates the interfacial properties and mechanical performance of polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) composites, which are crucial for automotive and electronic applications. By employing three distinct compatibilizers - styrene-acrylonitrile-glycidyl methacrylate (SAG), methyl methacrylate- butadiene-styrene (MBS), and cyclic butylene terephthalate oligomer (CBT) - and comparing one-step with two-step methods, we identified the critical role of both compatibilizer chemistry and processing strategy. The results demonstrate that the two-step method with SAG achieves superior compatibilization, yielding an optimal impact strength of 60.37 kJ/m2 and an elongation at break of 92 %. This enhancement is ascribed to the formation of covalent "chemical bridges" by SAG at the PC/ABS interface. In contrast, the non-reactive MBS and CBT compatibilizers, which rely on physical-chemical synergy and rheological wetting respectively, provided comparatively weaker improvements. This work elucidates the underlying mechanisms and provides a practical guideline for tailoring high-performance PC/ABS composites through selective compatibilization and processing.
The accuracy of injection molding simulations is largely dependent on the quality of the material data on which the flow calculations are based. Viscosity, as a measure of flow resistance in a plastic melt, is a key material property that significantly affects simulation results, especially the simulated injection pressure. The melt viscosity of a polymer is largely dependent on three factors: temperature, shear rate and pressure. A conventional high-pressure capillary rheometer (HPCR) can be used to measure viscosity in a shear rate range relevant for injection molding as a function of temperature and shear rate. However, conventional HPCR cannot determine the pressure dependence. Special devices, such as back pressure viscometers or back pressure chamber extensions, are required for this, but they are rarely available. Additionally, these measurements are time-consuming and expensive, which is why pressure-dependent viscosity data are rarely available. In this study, pressure-dependent viscosity data are calculated via a correlation between conventional viscosity data and pressure dependent melt density, utilizing the free volume approach based on the Simha & Somcynski equations of state (Simha, R. and Somcynsky, T. (1969). On the statistical thermodynamics of spherical and chain molecule fluids.Macromolecules 2: 342-350, doi: 10.1021/ma60010a005.). The advantage of this model calculation is that it is based on existing material data and is therefore particularly cost-effective. Subsequently, injection molding simulations of a mold with a hot runner manifold were carried out for both amorphous and semi-crystalline thermoplastics, using two different widely used commercial software solutions. The simulations were carried out using conventional pressure independent viscosity data and model-calculated pressure dependent viscosity data. Injection pressures were compared, revealing significantly higher injection pressures for amorphous polymers based on pressure-dependent data. Additionally, experimental injection molding tests were performed at simulated operating points to evaluate improvements in simulation accuracy.
Polymeric materials are essential for mechanical and aerospace applications due to their versatility. Among them, epoxy resin, a well-known thermosetting polymer, is frequently used as an adhesive, coating, and composite matrix because of its high performance, ease of processing, and low cost. However, the crosslinked structure of epoxy resin makes it brittle and limits its crack resistance. Adding nanofillers to the epoxy matrix can significantly improve mechanical strength, hardness, toughness, and multifunctionality. Three-dimensional graphene oxide (3D-GO) has an ultra-lightweight, porous structure with excellent electrical, thermal, and mechanical properties. Nanocomposites made with this structure outperform traditional two-dimensional graphene-based materials. In this study, 3D-GO was synthesized using a hydrothermal process followed by freeze-drying. The chemical composition and morphology of the resulting nanomaterials were characterized with diffraction, microscopy, and spectroscopy techniques. Then, a probe ultrasonicator was utilized to ensure uniform dispersion of nanoparticles within the epoxy resin over five consecutive 5-min intervals. This process resulted in the creation of a 0.5 wt% 3D-GO/epoxy nanocomposite for reinforcement testing. The mechanical behavior of the nanocomposite was experimentally evaluated under various loading conditions. Reinforcement using 3D-GO resulted in a 31 % and 37 % enhancement in compressive modulus and strength, a 18 % and 32 % increase in tensile modulus and strength, a 16 % and 41 % improvement in flexural modulus and strength, and a remarkable 98 % rise in impact strength. The results of this study indicate that incorporating nanoparticles into the resin not only enhances the mechanical properties but also significantly improves impact resistance. This demonstrates the substantial effect of 3D-GO nanoparticles in reducing the susceptibility of epoxy resin to dynamic loads. Therefore, it is anticipated that using this hybrid system will be advantageous for applications subjected to dynamic loading conditions. Fractographic analysis revealed that the three-dimensional structure of the reinforcing nanoparticles effectively mitigates interlayer bond failure and layer slippage within the matrix, thereby improving fracture resistance.
Plasticization of banana fiber (BF)-reinforced thermoplastic starch (TPS) must balance melt flowability during compounding with stability during service. Here, a stoichiometry-resolved processing map is established for an amine-based deep eutectic solvent (DES), choline chloride-monoethanolamine (ChCl:MEA; salt:donor 1:2-1:5), in composites containing 15 wt% BF, benchmarked against glycerol and reline (choline chloride:urea, 1:2). Processability was quantified by internal-mixer steady torque, specific mechanical energy (SME), and melt flow index (MFI). Solid-state response and early-life stability were assessed by dynamic mechanical analysis (DMA; glass transition temperature, Tg), scanning electron microscopy (SEM) fractography, and tensile testing after aging at 23 degrees C and 50 % relative humidity (RH) for up to 56 days. Replacing glycerol with ChCl:MEA halved the mixing load (torque: 9-10 N m; SME: 36-39 kJ/kg) and increased MFI from 0.89 to 1.67-2.01 g/10 min. A low-energy/high-flow window (SME <= 40 kJ/kg; torque <= 10.5 N m; MFI >= 1.8 g/10 min) occurred at ChCl:MEA = 1:3-1:4. Tg (DMA tan delta peak) decreased from 109.2 degrees C (glycerol) and 97.3 degrees C (reline, ChCl:Urea 1:2) to 84.1-74.8 degrees C across ChCl:MEA (1:2-1:5) at BF = 15 wt%, and day-56 elongation retention reached 80-84 % for 1:4-1:5 versus 50-60 % for the controls. Stoichiometric tuning of ChCl:MEA therefore enables efficient compounding while preserving early-life ductility.
With the growing demand for lightweight solutions to reduce emissions, especially in the transportation, automotive and aerospace sectors, recyclable, continuous fiber-reinforced plastic composite laminates with a thermoplastic matrix are of rising interest. To achieve their maximum mechanical properties, the fiber-matrix adhesion (FMA) is critical. In this work, continuous fiber-reinforced thermoplastic laminates (CFRTPL) with a polypropylene (PP) matrix and twill woven glass fiber fabrics are produced by film stacking. The films used contain different amounts of maleic-anhydride-grafted PP (MA-g-PP) as a coupling agent to produce CFRTPL of different mechanical strengths. To analyze the FMA, the CFRTPL are subjected to Charpy-impact and tensile tests. Additionally, single fiber pull-out tests (SFPT) are conducted to further investigate the effect of MA-g-PP on the FMA. The results of the SFPT show an improvement in apparent interfacial shear strength (AIFSS) when the MA-g-PP content is increased, which can be attributed to an increase in FMA. However, the research shows that MA-g-PP has a low impact on the mechanical properties if the force is applied parallel to the warp and weft threads during tensile testing and the results of the Charpy-impact testing suffer from embrittlement of the matrix material. Subsequently, the results of this study are compared to three-point flexural tests conducted in a previous study. It can be concluded that tensile and impact tests are not suited to investigate FMA on a macroscopic scale, while SFPT and flexural tests provide a better alternative.
