Thermoplastic Research Articles

Constructing micro-region networks in expanded graphite for bi-directional high thermal conductivity of thermoplastic polymer composite

Thermoplastic polymers have limited application in thermal management due to its low thermal conductivity (TC). Adding high TC fillers and hot-pressing process can effectively improve in-plane TC. However, single filler orientation limits through-plane heat transfer and most of polymer-based composites have low through-plane TC (<10 W/m·K). The preparation of polymer-based composites with bi-directional high thermal conductivity is still a great challenge. In this work, a novel maleic anhydride (MA) modified nano Al2O3 (M−Al2O3)/expanded graphite (EG)/PVDF composite (MAE/P) with bi-directional high thermal conductivity was prepared by a melt self-adsorption and hot-pressing method, where the EG was used for constructing the main thermal conductive network and the M−Al2O3 was embedded in EG 3D structure to build micro-region network to greatly increase the out-plane thermal conductivity (TC) of the composite. Results show that the through-plane and in-plane TC of the MAE/P were 13.78 W/m·K and 102.24 W/m·K (50 wt% filler content), respectively. The finite element simulation computation of microstructure also amply demonstrates the effectiveness of enhancing TC by gap filling. Research shows that the key to achieving bi-directional high thermal conductivity is that more phonon transmissionpathways were constructed along vertical direction when M−Al2O3 is embedded. Moreover, the MAE/P also indicates excellent thermal infrared response capability, electromagnetic interference shielding (87.22 dB at 70 wt% filler content) and mechanics performance (over 130 MPa bending strength at 50 wt% filler content). This work provides a new method to greatly enhance bi-directional TC of thermoplastic polymer-based composites.

Interlaminar toughening and self-healing mechanism for hard-and-soft layered composite laminates

This paper finds a simple and cost-effective design to create high interlaminar toughness and self-healing Euplectella Aspergillum based bio-inspired composite laminates with thermoplastic polymer poly(ethylene-co-methacrylic acid) (EMAA). Three different configuration strategies containing hard/soft structures are proposed and mode I interlaminar toughness is determined to investigate the toughening effect and self-healing behavior. The results show that configuration and fiber types have great influence on toughening and self-healing efficiency. The novel configuration can achieve an improvement of over 600% in toughness for carbon fiber reinforced plastic (CFRP) and close to 100% for healing efficiency in the case of glass fiber reinforced plastic (GFRP) laminates. All the proposed configurations eliminate unstable delamination crack propagation process observed in CFRP woven laminates. In addition, repeated self-healing behavior is studied and self-healing efficiency remains stable after three damage-healing cycles. This study reveals toughening and self-healing behaviors of different configurations and provides novel strategies for laminate design.

Investigation on Failure Mode of Short Carbon Fiber Reinforced Thermoplastic Composites Joints of Non-metallic Pipeline

Investigation on Failure Mode of Short Carbon Fiber Reinforced Thermoplastic Composites Joints of Non-metallic Pipeline

Shear Bond Strength Comparison Between Heat Cure Acrylic Resin and Other Types of Acrylic Denture Bases

Objective: The study purpose was to examine the shear bonding strength of heat cure acrylic resin to thermoplastic resin and three-dimensional printed resin materials. Methods: A total of 30 acrylic specimens were fabricated in this study. Each specimen had a basal and top parts. The basal part was rectangular in shape. We had three different groups: 10 specimens of a basal part made of heat cured polymethylmethacrylate, 10 specimens of a basal part made of thermoplastic, and 10 specimens of three dimensionally printed resin. The top part of which is attached to the basal one was formed into a cylindrical shape made of heat cure poly methyl methacrylate in all three groups. Results: Significant differences were found between the heat cured polymethylmethacrylate and the other two groups (P&lt;.001). Heat cured polymethylmethacrylate showed the highest bond strength (75 MPa), and thermoplastic resins showed the lowest (37 MPa). No significant difference in the shear bond strength was noticed between three dimensionally printed and thermoplastic acrylic. Conclusion: This study revealed that the shear bond strength of heat cured acrylic denture base to the relining/repairing from the same material was significantly higher than three dimensionally printed and thermoplastic resins with HC relining/repairing material.

Quantitative Prediction of Polymer Dielectric Constants Using an Improved Mathematic Correlation Based on Molecular Polarity Components

ABSTRACTThe advancement of communication technology has significantly promoted the development of dielectric polymers. However, the quantitative prediction of dielectric constant for rapid material screening is hard due to the low precision of existing theories. In this paper, a new model was developed to calculate the dielectric constants of organic materials through theoretical deduction correlating to the dielectric and polar Hansen solubility parameter (HSP) functions (). This model treated the permanent dipole moments as the primary function determining the dielectric constant and the corresponding polar HSP, which was demonstrated to be in good agreement with experimental data and produced reasonable fitting for organic solvents, thermoplastic polymers, and thermoset polymers, yielding R2 of 0.7488, 0.8104, and 0.7450, respectively, and it demonstrated better fitting with R2 of 0.9043 when applied to organic solvents having low hydrogen bonding component (, &lt; 12.5). This new correlation produces the highest accuracy of prediction when compared to the existing models and provides a better mathematical tool to help design and screen dielectric polymers.

Enhancing friction with additively manufactured surface‐textured polymer composites

AbstractIncreasing rubber's friction on slippery surfaces provides protection against falls; however, surface‐textured composites, despite their potential, remain susceptible to wear. To address this issue, part of our team previously patented a surface‐textured composite made from thermoplastic polymers and microfibers. This study investigates the impact of manufacturing processes and 2D filler, which are known for their hydrophobicity and large surface area. It enhances our patented composite by integrating 2D graphene nanoplatelets (GNP), hexagonal boron nitride (hBN), and fillers like styrene‐butadiene‐styrene (SEBS), and silica, while comparing the properties of composites fabricated via injection molding (IM) and fused filament fabrication (FFF). The results demonstrate that 2D fillers enhance both abrasion resistance and ice friction, while FFF‐fabricated composites consistently exhibit superior properties across all compositions. Notably, hBN‐reinforced samples exhibited hierarchical surface texturing, leading to enhanced abrasion resistance (FFF: 146.63% ± 3.39%; IM: 133.83% ± 6.8%; p = 0.036), and effective ice traction (FFF: 0.58 ± 0.04; IM: 0.54 ± 0.06; p = 0.043). These outperformed ice‐traction properties of all other FFF‐fabricated composites, including a previously patented composite (0.52 ± 0.05) as well as composites with GNP (0.53 ± 0.02), SEBS (0.42 ± 0.05), and hBN + SEBS (0.45 ± 0.02). Additionally, the patented composite produced via FFF exhibited moderate oil traction (0.121 ± 0.001), outperforming others. This study highlights the potential of FFF and 2D fillers to enhance traction and durability in composites.Highlights Surface‐textured composite introduced via additive manufacturing. Abrasion resistance and friction analysis on icy and oily conditions. Reveals the potential for new composite to improve traction and longevity. Highlights the importance of controlled fiber distribution and orientation.

Multilayer composites for improved mechanical performance of flexible rapier tape

Currently, laminated composites are used in the design and development of commercial rapier tapes employed in rapier weaving machines for weft insertion mechanisms. However, 3D woven reinforcements have the potential to enhance the mechanical performance of rapier tapes. This study focuses on comparing textile composites made from three different woven reinforcements i.e. plain 1/1, 2/2 twill, and a 3D woven orthogonal through the thickness and three different resins i.e. unsaturated polyester, epoxy, and acrylic. The developed composites underwent mechanical testing tailored for flexible rapier tapes. The results revealed that 3D-reinforced rapier tape composites (RTCs) exhibited higher tensile stress, strain at break, flexural force, flexural modulus, storage modulus, and stiffness compared to RTCs with 2D woven reinforcements. Among the resins, epoxy demonstrated superior mechanical performance across most properties, outperforming unsaturated polyester and thermoplastic acrylic resin. The developed single 3D multilayer reinforcement presents a feasible alternative for fabricating RTCs, with the potential to reduce energy.

Analysis of Mechanical Properties of Components Produced by Additive Manufacturing

This paper analyses the effect of various lattice structures and lattice vectors on the mechanical properties of components made with acrylonitrile butadiene styrene (ABS) material by fused deposition modeling (FDM) technique. ABS is a well-known thermoplastic polymer that is being used in a variety of applications because of its high durability and good adaptability. A total of nine varieties of lattice structures are examined, including regular variations like hexagonal and cubic patterns and more complex ones like Gyroid patterns in this paper. Lattice vectors like 4–6 mm were considered while preparing the components. The densities of the specimens were estimated, and the specimens were tested for their flexural strength and compression strength. The results show that “Gyroid minimal surface” structures are a better choice for flexural and compression strength applications.

Multi-scale numerical calculations for the interphase mechanical properties of carbon fiber reinforced thermoplastic composites

This study employs a multi-scale numerical calculations method based on molecular dynamics and finite element modeling to investigate the stress transfer mechanisms within the interphase of unidirectional (UD) carbon fiber reinforced thermoplastic polymers (CFRTP) composites, based on which exponential decay model (EDM) was developed to predict the interphase strength and modulus. Revealing that the interphase strength and modulus are approximately 0.5–0.7 times that of the fibre/interphase interface or 1.2 to 1.7 times matrix. The EDM was validated using a coupled experimental-representative volume element modeling method. By calibrating the interphase fracture energy, the mechanical properties predicted by the EDM aligned well with the experimental results of UD CFRTP composites. Finally, the damage evolution and failure modes were analyzed, revealing that the transverse failure of UD CFRTP composites is dominated by the interphase, while longitudinal failure is primarily governed by the fibers, consistent with scanning electron microscope observations. This confirms the accuracy of the EDM, and application this method can be used to quickly and accurately assess the strength and modulus of the interphase in CFRTP composites to significantly reduce the numerical analysis time.

Epoxy-Benzoxazine Powder Binders for Producing Reinforced Composites with a Matrix Gradient

Carbon composites with graded binder distribution along the product cross-section were developed using epoxy-benzoxazine powder binders. Their rheological, thermophysical, and physicomechanical properties were analyzed. It was demonstrated that graded compositions offer certain advantages in providing control over the parameters of the production process, both during the plate consolidation and the final product formation by pressing. The production of dry prepregs by electrostatic spraying of powder binders on carbon fiber followed by melting, the consolidation of prepregs into plates by vacuum bagging, and subsequent pressing of the plates to obtain the product were optimized. The feasibility of producing a graded carbon composite with enhanced physicomechanical and thermophysical properties was revealed for powder compositions based on benzoxazine, thermoplastic polymer, and epoxy-novolac and epoxy resins. Binder compositions with a gradient of components were proposed. A positive effect of the matrix gradient on lowering the temperature gradient during thermal pressing was confirmed.

Carbon Nanotube-Based Segregated Thermoplastic Nanocomposites Structured via Electromagnetic Melt Processing.

A cutting-edge method that uses electromagnetic (EM) energy for the melt processing of thermoplastic polymer nanocomposites (TPNCs) is reported. The properties and microstructures of TPNCs produced via the proposed EM-processing method and TPNCs via conventional heat processing are contrasted. The EM-processed TPNCs prepared with EM-susceptible carbon nanotubes (CNTs) exhibited a significant enhancement in transport and mechanical properties, outperforming the conventionally processed TPNCs. Thus, the EM-processed TPNCs demonstrated an ultralow electrical percolation threshold (∼0.09 vol %) and a remarkable increase in volume electrical conductivity of 8 orders of magnitude (i.e., 1.1 × 10-5 S/m) at only 1.0 wt % CNT loading, compared to their hot-pressed counterparts. This highlights the superior network formation, level of segregation, and structuring enabled by EM processing. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) revealed that EM-processed TPNCs exhibited higher crystallinity (∼9% higher) and a predominantly α crystal phase compared to the hot-pressed TPNCs. Microstructural inspection by electron microscopy disclosed that EM processing led to segregated but interconnected multiscale networks of a thin and well-defined CNT interphase that encompassed from the nanoscale of the CNTs to the macroscopic scale of TPNCs. In contrast, conventional processing developed a more diffused CNT interphase with less interconnectivity. The EM-processed TPNCs developed a statistically higher stiffness (+20%) and in certain cases, even better strength (+10%) than the hot-pressed TPNCs. However, the EM-processed TPNCs displayed significantly lower ductility, owing to their higher crystallinity, more brittle crystal α phase, and the potential formation of microvoids in the bulk of the TPNCs inherent to the unoptimized EM processing. This work provides an understanding of an alternative and unconventional processing method capable of achieving higher structuring in nanocomposites with advanced multifunctional properties.

Boosting the structure, thermal, optical and dielectric properties of a thermoplastic polymer by some nanoperovskites

Boosting the structure, thermal, optical and dielectric properties of a thermoplastic polymer by some nanoperovskites

Theory-guided machine learning for thermal modeling of in-situ automated fiber placement of thermoplastic composites

In-situ Automated Fiber Placement (AFP) of thermoplastic composites has several advantages over traditional manufacturing techniques, with the main benefit being eliminating secondary thermal processing. Without secondary heat treatment, the in-situ thermal history becomes the critical process parameter that governs bond development, crystallization kinetics, and the development of residual stresses. This work improves the thermal modeling of the in-situ Automated Fiber Placement (AFP) manufacturing process by leveraging Theory-Guided Machine Learning (TGML). A novel theory-guided neural network (TgNN) with theory-based pre-layer transforms models the three-dimensional temperature distribution during in-situ AFP manufacturing. The TgNN is fit on experimentally measured temperatures for various combinations of hot gas torch temperatures and heat source velocities. Feature engineering is implemented by applying theory-based pre-layer transforms to the input features time, the thermocouple coordinates, hot gas torch temperature, and heat source velocity. Compared to a theory-agnostic neural network, the TgNN with theory-based pre-layer transforms has improved predictive ability and requires fewer training data for equivalent performance. The trained model is computationally efficient and can be leveraged for online process control.

Multi-Scale Mechanical Behavior of Liquid Elium® Based Thermoplastic Matrix Composites Reinforced with Different Fiber Types: Insights from Fiber–Matrix Adhesion Interactions

Multi-Scale Mechanical Behavior of Liquid Elium® Based Thermoplastic Matrix Composites Reinforced with Different Fiber Types: Insights from Fiber–Matrix Adhesion Interactions

Experimental study on the electrical conductivity and strain sensitivity of fibre-reinforced thermoplastic for structural health monitoring

This experimental study explores the mechanical, electrical, and piezometric characteristics of conductive thermoplastic polymers reinforced with short carbon and glass fibres. The work investigates how the local anisotropy induced during the manufacturing injection process impacts the properties of the composite. Tensile tests showed that the material orientation respect to the injection flow direction significantly affects the mechanical properties due to the alignment of the fibres with the injection flow, as shown through microscopy analysis. Contrarily, electrically conductive tests showed that the influence of the orientation on the conductive properties of the material is negligible. The study also unveils the difference in the surface and bulk conductivity with the increasing distance of the electrodes. Tensile tests with in-situ electrical measurements were conducted to assess strain sensitivity by correlating stress–strain curves with changes in material conductivity. The results demonstrate the predominant impact of local anisotropy on piezometric response. Finally, a model for the piezometric response of the material is proposed and applied for the structural health monitoring of a tensile specimen, revealing its ability to detect local damage before final failure. This application underscores the prognostic capabilities of this material and its potential significance in ensuring structural integrity.

The Role of Chemical Treatments on Curaua Fibers on Mechanical and Thermal Behavior of Biodegradable Composites

Biodegradable composites combining thermoplastic polymers and natural fibers could originate materials with synergetic mechanical and thermal properties, keeping their biodegradability. This paper describes biodegradable polymers’ mechanical and thermal properties, such as polylactic acid (PLA) and polyhydroxybutyrate (PHB) reinforced with curaua fibers. To improve the interface between matrix and reinforcement, the curaua fibers were treated by two routes: (1) treatment with hot water and subsequent mercerization with NaOH; (2) treatment with chlorite and subsequent mercerization with NaOH. The composites of PLA and PHB reinforced with natural or modified fibers (10 and 20 wt%) were obtained by extrusion and injection molding. The influence of fiber content and treatment on composite properties was studied by tensile and flexural tests, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results showed the removal of hemicellulose and lignin from the fibers, increasing their crystallinity and slightly decreasing their thermal stability after chemical treatments. Also, the DSC technique showed that the insertion of the curaua fibers increased the crystallinity index of all composites/PLA. The mercerized-curaua (20 wt%)/PLA composite showed the best result in the mechanical behavior, both in tensile and bending tests. The PHB composite, reinforced with curaua fibers and treated with hot water and mercerization (20 wt%), showed the best result regarding mechanic performance. To conclude, all composites improved mechanical properties compared to pure polymers.

Recent advances of interfacial modifications toward carbon fiber‐reinforced thermoplastic polypropylene and polyamide composites

AbstractThe performance of carbon fiber‐reinforced thermoplastic composites (CFRTP) has been restricted by the performance of the interface. In general, the interfacial properties of CFRTP are determined by both the surface properties of the carbon fiber (CF) reinforcement and the infiltration properties of the thermoplastic matrices, which possess high melt viscosity and seem difficult to sufficiently infiltrate the fiber reinforcement. As a result, the melt flow characteristics of different matrices significantly influence the interfacial melt penetration and mechanical properties of CFRTP. In this paper, in order to explore the influence of melt flow characteristics of various thermoplastic resins toward CFRTP interfacial behaviors, high‐polarity polyamide (PA) and low‐polarity polypropylene (PP) resins are selected as representative resin matrices among commonly used resin systems. Specifically, the polarity differences and interface‐forming mechanisms of CFRTP are first established. Following a systematical discourse on the latest research progress of interfacial modifications in PP/PA‐based CFRTP are described, centering on the effects of various modification methods on improving the interlaminar/interfacial strength, toughness, impact strength, and bending strength of the composites. In addition, this paper also classifies the interfacial mechanisms of CFRTP in terms of interface bonding, interface strengthening, and interface failure. Finally, the shortcomings and future research directions are pointed out to achieve effective interfacial construction and innovative modification of CFRTP.Highlights An introduction of resin polarity differences of CFRTP is established. An introduction of interface‐forming mechanisms of CFRTP is established. State‐of‐art characterization techniques of CFRPs interface are provided. Effect of melt flow property on the interfacial behavior of CFRTP was explored. The interfacial mechanisms are systematically analyzed.

Green and highly efficient preparation of superfine fiber yarns via vortex airflow-assisted melt differential electrospinning

Vortex airflow-assisted melt differential electrospinning for preparing superfine fiber yarns was proposed. This method with solvent-free exhibits a higher yield of 20 ± 5.17 m/min compared to the range of 0–5 m/min achieved by solution electrospinning with organic solvents. Simulation and high-speed photography show that the fibers are aggregated by suction airflow and twisted into yarns by vortex airflow. Polylactic acid (PLA) superfine fiber yarns exhibit fine fiber diameters ranging from 0.96 to 5.57 μm, a yarn diameter of 211.7 ± 40.8 μm, and a high tensile strength of 39.4 ± 3.12 MPa. Furthermore, these PLA melt electrospun yarns can be woven into fabric with a water contact angle of 120.1° and triboelectric voltage of 7.41 V, demonstrating their potential in self-cleaning textiles and flexible smart textiles. Moreover, this method is generally applicable to thermoplastic polymers including polyethylene terephthalate (PET), polypropylene (PP), and polycaprolactone (PCL). It provides a promising approach for green industrialization of superfine fiber yarns.

Study of alternatives for preserving enamelled goldware using thermoplastic acrylic resin via scientific examination

Study of alternatives for preserving enamelled goldware using thermoplastic acrylic resin via scientific examination

Fiber-Reinforced Thermoplastic Composites for Future Use in Aircraft Radomes: Biomimetic Design Approaches and Its Performances

Fiber-Reinforced Thermoplastic Composites for Future Use in Aircraft Radomes: Biomimetic Design Approaches and Its Performances