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A multiple injection compression molding (ICM) method was proposed on the basis of injection molding and applied for the preparation of polypropylene/short carbon fiber (PP/SCF) high thermally conductive composites in this article. During each injection compression cycle, the thickness of composite sample would be reduced effectively for better SCF orientation along the flow direction. Moreover, the original loose self‐assembled SCF networks obtained from injection process can furtherly transfer into much compact ones under the effect of compression force. The performance differences among SCF/PP composites prepared with one‐time injection molding (IM), multiple IM, and multiple ICM were also investigated. The SCF/PP composite sample prepared with multiple ICM method presented superior comprehensive performance, ~100% and 28% enhancements in thermal conductivity and tensile strength compared with the one‐time IM sample. We believe the multiple ICM method can provide a new idea for industrial production of functional polymer composites, especially for thermoplastic polymer composite. [ABSTRACT FROM AUTHOR]

Polyetheretherketone (PEEK) is a high‐performance plastic with favorable physical, mechanical, chemical, and biological properties for various industrial applications. Most PEEK substrates/components are manufactured using traditional methods like milling, compression molding, injection molding, pressure sintering, and so forth. With the advent of various additive manufacturing (AM) techniques, researchers have been working on optimizing the processing parameters for AM of PEEK. Furthermore, several PEEK composites with improved properties have also been developed, and efforts have also been made to use these PEEK composites in AM. Since AM of PEEK and its composites is a relatively new area of the advanced manufacturing process, the field faces many challenges. There is a dearth of comprehensive reports on this topic. Keeping this perspective in mind, we have tried to collate the relevant information on the composites and AM of PEEK in this review. The review highlighted the influence of variation in composition on material properties and performance of PEEK and showed the correlation with AM processability of such composites. A detailed analysis of the various reports on fused deposition modeling and selective laser sintering based processing of PEEK composites is included in the review. Critical barriers to the AM of these high‐performance polymer composites are pointed out. We have also included the outcome of some interesting studies about the coating of PEEK with various materials/compounds to provide a broader perspective. This review will help the researcher to design and develop additively manufactured PEEK‐based structures with improved and customized properties. [ABSTRACT FROM AUTHOR]

The research article deals with the efficacy of turtle shell powder (TSP) as an attempt at a novel perspective vision, used as a filler material in the fabrication of basalt‐epoxy composites preparation for us as a first opportunity. The fiber reinforced polymer composite made of basalt‐epoxy matrix was fabricated by filling TSP powder with different weight percentage levels of 1%, 3%, and 5% by hand lay‐up process continued by a compression molding technique. In addition, the single laminate basalt fiber ply orientations were configured by symmetric‐quasi‐isotropic. Density, tensile, flexural, impact, and hardness tests were performed to analyze the composite strength and modulus. The morphological traits and TSP elemental composition were analyzed by scanning electron microscope and EDAX, respectively. Results elucidate that the incorporated TSP particle in basalt‐epoxy composite enhanced the mechanical properties. Overall compared with the B0 composite, the B3 composite exhibits the optimal result, the tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength increased by 98.4%, 68.9%, 70.73%, 53.12%, and 76.85% performance explicates, respectively, except hardness, which shows 43.5% higher in 5 wt% composite. The interfacial bonding of basalt‐epoxy composites has been improved by the TSP particle curtailed the microvoids. The basalt‐epoxy characteristics were adversely affected by TSP aggregation that occurred at 5 wt% laminate. The laminated composites are heavily bolstered by the performance of TSP particles and with the addition of ply orientation increased the strong interfacial bonding of TSP‐epoxy‐basalt interactions. [ABSTRACT FROM AUTHOR]

Polymer composites are ubiquitous and indispensable in numerous applications. Coupling the inclusion of reinforcing agents with methods developed to control filler distribution and orientation allow for significant enhancement in mechanical, thermal, electrical, and barrier/transport‐related properties of composites. For practical implementation, ideal approaches to fabricating polymer composites with directionally assembled fillers must consider manufacturing compatibility, scale‐up ease, and aligning efficiency. In this article, we will review a cost‐effective and industrially relevant toolbox for preferential filler alignment in polymer composites. Three main strategies for aligning fillers within polymer composites will be discussed. Specifically, solution casting and compression molding can introduce compression force to assemble fillers along the in‐plane direction of composite films, shear force can be developed during fiber spinning, film blowing, and uniaxial/biaxial stretching processes to align fillers along the shear direction, and external fields (both electric and magnetic fields) can direct assembly of fillers, typically along the out‐of‐plane direction. For each section, we not only highlight the mechanisms of these methods but also demonstrate the critical structure–property relationships through model examples. Finally, a perspective on future opportunities and challenges of anisotropic and performance‐enhanced polymer composite preparation strategies is provided, with a particular focus on additive manufacturing. [ABSTRACT FROM AUTHOR]

A modeling method of the anisotropic magnetic characteristics due to compression molding of a soft magnetic composite (SMC) for inductance calculation of an SMC inductor is proposed. First, a particle model with a flattened iron particle and a uniform layer of insulation is constructed to simulate the anisotropic BH curves in arbitrary directions using the measured limited two BH curves in the compress and vertical directions under compression. Then, the proposed particle model is expanded to include the dc-biased characteristic of permeability. Moreover, the proposed model is applied to two inductors with legs having different compress directions. It is shown that the proposed method can be applied to the optimal design of inductors taking account of the compress direction of SMC. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs)-reinforced polyurethane (PU) composites were fabricated by using solution mixing technique followed by compression molding. Nano dynamic mechanical analysis was carried out to investigate the viscoelastic properties of PU/MWCNTs composites within a frequency range of 5–250 Hz. At higher frequencies (250 Hz), the storage modulus of PU/MWCNTs composites with 10 wt% loading of MWCNTs was enhanced by 148% in equivalence to pristine PU. An improvement of 13.3% in storage modulus was observed at a loading frequency of 250 Hz in comparison to that of a loading frequency of 75 Hz, which indicates that the effect of MWCNTs on storage modulus was more pronounced at higher frequencies. At 75 Hz, a minor composition of MWCNTs (3 wt%) was sufficient to reduce the value of tan δ from 0.20 to 0.15, indicating that the material becomes more elastic after reinforcing MWCNTs. This significant improvement in the mechanical behavior of composite material has been attributed to the uniform dispersion of MWCNTs, and their adhesion with PU molecules. Reported enhancement in the elastic behavior of PU composite will boost the applicability of PU-based composite material for the fabrication of high-strength boots, gloves, and jackets required to absorb high vibration frequencies experienced during conditions such as rock drilling. [ABSTRACT FROM AUTHOR]

The presented research was focused on the development of a new method of sandwich structure manufacturing involving FDM-printing (fused deposition modeling) techniques and compression molding. The presented concept allows for the preparation of thermoplastic-based composites with enhanced mechanical properties. The sample preparation process consists of 3D printing the sandwich's core structure using the FDM method. For comparison purposes, we used two types of GPET (copolymer of polyethylene terephthalate)-based filaments, pure resin, and carbon fiber (CF)-reinforced filaments. The outer reinforcing layer "skins" of the sandwich structure were prepared from the compression molded prepregs made from the LCP (liquid-crystal polymer)-fiber fabric with the GPET-based matrix. The final product consisting of an FDM-printed core and LCP-based prepreg was prepared using the compression molding method. The prepared samples were subjected to detailed materials analyses, including thermal analyses (thermogravimetry-TGA, differencial scanning calorimetry-DSC, and dynamic thermal-mechanical analysis-DMTA) and mechanical tests (tensile, flexural, and impact). As indicated by the static test results, the modulus and strength of the prepared composites were slightly improved; however, the stiffness of the prepared materials was more related to the presence of the CF-reinforced filament than the presence of the composite prepreg. The main advantage of using the developed method is revealed during impact tests. Due to the presence of long LCP fibers, the prepared sandwich samples are characterized by very high impact resistance. The impact strength increased from 1.7 kJ/m2 for pure GPET samples to 50.4 kJ/m2 for sandwich composites. For GPET/CF samples, the increase is even greater. The advantages of the developed solution were illustrated during puncture tests in which none of the sandwich samples were pierced. [ABSTRACT FROM AUTHOR]

This paper discusses the fabrication of nano ZnO filled epoxy/basalt fiber composites and investigates the effect of such hybridization on the mechanical properties of the composites. The epoxy resin is modified by the addition of ZnO nanofiller in different wt.% (1–5 wt%). The dispersion of the nanofiller within the epoxy resin is brought about by sonication technique. The composites are fabricated through wet layup followed by curing under compression molding. To ascertain the effect of resin modification, flexural and tensile strengths are evaluated. The inter‐laminar shear strength (ILSS) is determined to identify the compatibility of the ZnO nanofiller with the epoxy and the basalt fibers. The improvement in the ILSS indicates thorough wettability being achieved between all the composite components. The addition of ZnO nanofiller improved the flexural strength, while there was no remarkable improvement in the tensile strength of the ZnO modified epoxy/baslat (BEZ) composite. Maximum improvement in the strengths is observed for BEZ2 composite with 2 wt% of ZnO nanofiller. For BEZ2 composite, the flexural and tensile strength increased by about 22% and 9.78% respectively in comparison to unfilled BEZ0 composite. The ILSS for BEZ2 composite improved by 21.74% in comparison to BEZ0 composite. In addition, more than 2 wt% addition of the ZnO nanofiller resulted in the reduction of flexural, tensile and ILSS of the composite due to agglomeration. Such agglomeration resulted in the failure of the composite due to delamination, matrix cracking and fiber fracture as observed through scanning electron microscopy images of the fractured composites. [ABSTRACT FROM AUTHOR]

With respect to the explosion of single‐use plastic packaging consumption during the COVID‐19 pandemic, environmentally friendly substitutes are critically needful for sustainable development. Therefore, the present work focuses on the functional properties of bioplastic blends prepared through hot compressing molding of thermoplastic starch (TPS) and spent coffee grounds (SCG) in different ratios (0%–20% SCG) as the potential features of SCG were extensively employed in biocomposites for the first time. The insertion of dark brown SCG into TPS hindered UV transmission by 100% at 320 nm and 99.2% at 400 nm. Moreover, the samples with 15% and 20% SCG induced a surge in radical scavenging activity from 7.95% to over 92% at a concentration of 0.1 g/ml owing to the rich source of antioxidants in SCG. The lignin component and high carbon content also improved the thermal performance of TPS/SCG blends, enhancing thermal stability, delaying onset and maximum degradation temperatures, and achieving the HB rating in the UL‐94 test. Compared to a pure TPS matrix, TPS blends incorporating up to 10% SCG exhibited improvement in elastic modulus without deterioration of tensile strength. [ABSTRACT FROM AUTHOR]

Ultra‐low density nitrile butadiene rubber (NBR)/polyvinyl chloride (PVC) composite foams that exhibit satisfactory compressive behavior and energy absorption characteristics were prepared by one‐step compression molding. The properties of the NBR/PVC foams, including the density, hardness, cell morphology, compressive behavior, energy absorption characteristics, and shock absorption characteristics, were studied with various concentrations of azodicarbonamide (AC). Further that, the ideality factor and the energy absorption efficiency of the NBR/PVC foams at a low stress for application in compression and energy absorption were determined. The results revealed that the densities of polymeric foams were crucial in determining the uniformity of cell size and energy absorption characteristics of the composite foams. With increasing AC content, the density of the NBR/PVC foams decreased linearly, whereas the uniformity of cell size and the foaming ratio increased; furthermore, the hardness and compression modulus gradually decreased, and the linear elastic region in the compressive stress–strain curves became narrow. When the applied stress was less than 100 kPa, the foams with a high AC content exhibited higher energy absorption compared to foams with a low AC content capacity because of the deformed cell wall and lower elastic modulus; however, the relation between AC contents and energy absorption was complicated above 100 kPa. The optimum springrate ratio was found at the concentration of 25 phr of the AC blowing agent. [ABSTRACT FROM AUTHOR]

Reinforcing fibers, nanofillers, matrix materials, and manufacturing techniques all have a role in the mechanical characteristics of hybrid composites. MWCNTs-reinforced E-glass/Kevlar/epoxy composites are appropriate fillers for structural applications. The impact of different concentrations of MWCNT fillers (0.4%, 0.8%, and 1.2% wt) on the mechanical characteristics of hybrid composites has been studied. Tensile and bending strength, as well as hardness, were measured in compression-molded composites. The effects of compression pressure, mold temperature, and applied pressure on hybrid (0.8% MWCNT) were investigated. When it came to composite tensile and bending strength, compression pressure was the most important factor, closely succeeded by mold temperature and pressure period. Compression molding were optimized, resulting in a tensile strength of 183 MPa, a bending strength of 158.3 MPa, and a hardness value of 23.8 HV. [ABSTRACT FROM AUTHOR]

The use of amorphous microspheres as filler in composites is promising due to their light weight, low cost, incombustibility, and the ability to alter relevant properties of the final composite. Contrary to glass spheres, perlite microspheres are much cheaper and can be tailor-made to facilitate purpose-oriented alteration of the final composite. We report the use of perlite microspheres for the preparation of: (1) composites, through a compression molding (hot pressing) technique; and (2) composite filaments, in a single screw extruder, as well as their use for sample printing through Fused Deposition Modeling (FDM). Proper characterization of the produced composites allows for their evaluation in terms of physical, thermal, and mechanical properties and with regards to the manufacturing technique, the filler fraction, and size. Composite samples of acceptable quality in terms of filler survival and dispersion as well as mechanical properties were produced through compression molding using fine expanded perlite microspheres (<90 μm) up to an infill ratio of 40 vol.%. Fine fillers (<90 μm) performed well in FDM, allowing printing of composite dogbone samples with a higher Young's modulus and elongation and similar ultimate tensile strength compared to benchmark, up to an infill ratio of 20 vol.%. Composite samples present a slightly lower burning rate compared to those produced solely by ABS. Perlite microspheres present good workability in both applications, possessing satisfactory performance as filler in the composites, and can thus be assumed a promising multifunctional filler for various thermoplastics considering their low price, environmental impact, and fire rating. [ABSTRACT FROM AUTHOR]

The use of carbon fiber-reinforced plastics (CFRP) is markedly increasing, particularly for the manufacturing of automotive parts, to achieve better mechanical properties and a light weight. However, it is difficult to manufacture multi-material products because of the problems due to the adhesive between CFRP and steel. The prepreg compression molding (PCM) of laminated CFRP can reduce the production time and increase the flexibility of the manufacturing process. In this study, a new manufacturing process is proposed for CFRP reinforcement on a hot stamped B-pillar using PCM. A finite element (FE) simulation of the hot stamping process is conducted to predict the dimensions of the B-pillar. The feasibility of PCM manufacturing is explored by the simulation of the thermoforming of a CFRP set on a shaped B-pillar. The temperature conditions of the CFRP and B-pillar for the PCM are determined by considering the heat transfer between the CFRP and steel. Finally, the PCM of the B-pillar consisting of steel and CFRP was performed to compare with the analytical results for verification. The evaluation of the B-pillar was conducted by the observation of the cross-section for the B-pillar and interlayer by scanning electron microscopy (SEM). As a result, a steel/CFRP B-pillar assembly could be efficiently manufactured using the PCM process without an additional adhesive process. [ABSTRACT FROM AUTHOR]

There has been extensive research in the field of material-extrusion (Mat-Ex) 3D printing to improve the inter-layer bonding process. Much research focusses on how various printing conditions may be detrimental to weld strength; many different feedstocks have been investigated along with various additives to improve strength. Surprisingly, there has been little attention directed toward how fundamental molecular properties of the feedstock, in particular the average molar mass of the polymer, may contribute to microstructure of the weld. Here we showed that weld strength increases with decreasing average molar mass, contrary to common observations in specimens processed in more traditional ways, e.g., by compression molding. Using a combination of synchrotron infra-red polarisation modulation microspectroscopy measurements and continuum modelling, we demonstrated how residual molecular anisotropy in the weld region leads to poor strength and how it can be eradicated by decreasing the relaxation time of the polymer. This is achieved more effectively by reducing the molar mass than by the usual approach of attempting to govern the temperature in this hard to control non-isothermal process. Thus, we propose that molar mass of the polymer feedstock should be considered as a key control parameter for achieving high weld strength in Mat-Ex. [ABSTRACT FROM AUTHOR]

The aerospace industry has an issue of disposing of waste, unused carbon fiber unidirectional prepreg tapes. This paper explores producing chips using sheet-molding compounding equipment (SMC) for conversion into products via compression molding, which are stronger than traditional glass-reinforced SMC parts due to the carbon fiber and high strength epoxy resin. Without a means to convert the continuous tape prepreg into chips, it will not be possible to convert the prepreg into a useful product and provide a way to reduce flow to the landfill and produce less expensive, lighter, and stronger parts for the transportation industry. The cure state of the epoxy resin in the prepreg tapes, which is affected by the amount of time the material has spent stored at elevated or room temperatures, significantly changes the ability of the material to be chopped into short fiber chips. In addition, equipment-related factors affect the material's ability to be chopped by the SMC equipment. This paper accounts for each of these factors and uses statistical methods to design experiments to investigate the impact each of these material-related and equipment-related factors on the success of the cutting portion of the process. The level of cure, as defined by endothermic peak, glass-transition temperature (Tg), or heat of reaction/degree of cure, has the greatest impact on the cutting process. For material with a moderate level of cure, the sharpness of the blades in the cutting roller also has a major impact on the success of the process. The cutting pressure, roller speed, and tape tension also have an impact on the success of the process, but impact of these factors lessens for feedstock prepreg with a sufficiently high level of cure. An optimal setup was determined, and general rules of thumb for selecting material and equipment settings were established. [ABSTRACT FROM AUTHOR]

The recent global pandemic has created a grave concern and awareness about the importance of the environment. The researchers/engineers/scientists are now focusing their efforts on the development of technologies that can ensure the sustainable growth of communities. Materials are at the core of every technological advancement. Natural fiber-based composites are a class of sustainable materials being used in diverse engineering applications, ranging from automotive to household goods. The processing methods, such as hand lay-up, injection, and compression molding are used extensively to fabricate simple composite parts. However, for complex/intricate product designs, the parts/components are made independently and these are assembled to get the final product. Joining thus becomes an inevitable process ensuring the assembly of parts/components. In the current experimental investigation, the hot-plate welding (HPW) behavior of sisal/jute fiber (both woven and short) reinforced polypropylene (PP) composite specimens fabricated using direct compression molding(DCM) and Extrusion injection molding (EIM) have been analyzed. The process parameters optimization has been achieved using the Taguchi experimental design approach. The hot plate welded joints of jute/sisal/PP composites were further investigated on the basis of their flexural and tensile properties. The failed joint specimens were characterized using TGA and XRD characterization techniques to analyze any changes occurred in their thermal degradation and crystalline behavior during welding process. The failure mechanisms of the joints have been thoroughly analyzed using SEM micrographs. [ABSTRACT FROM AUTHOR]

Replication of micro/nano-scale optical components onto non-planar substrates is considered technically challenging and excessively expensive via existing manufacturing approaches. A low-cost, large-volume and high-precision fabrication approach is thus highly desirable. In this paper, a novel precision compression molding approach that enables large-volume and high-resolution replication of micro/nano-scale optical features from planar to non-planar substrates is proposed. A micro-lens array is demonstrated to be transferred from a planar master mold to a non-planar substrate. In such process, a micro-lens array mold is initially fabricated by single-point diamond turning on a planar mold surface and then replicated by micro-injection molding. After that, the optical structures are transferred from micro-injected polymeric samples to a nickel foil by electro-plating, which is employed as a critical transition medium. To obtain sufficient flexibility with considerable strength, the thickness of the electro-plating mold is controlled to be around 75 μm, which is further integrated with precision molding tools to replicate micro/nano-scale optical features onto cylindrical substrates. Geometrical profile and surface roughness of the fabricated optical components in each processing step are characterized experimentally. The results indicate that the replication of the micro-lens array successfully demonstrates the process to transfer micro-optical components from planar surfaces to non-planar thermo-plastic polymeric substrates with high fidelity and optical-level surface quality. Compared with conventional precision compression molding, this novel proposed method in this research could achieve much higher flexibility and comparable fidelity with low cost on transferring optical structures from planar to non-planar surfaces. The application of this method might be widely extended to numerous replication methods, such as precision glass molding, roll-to-roll and roll-to-plane imprinting. • A new flexible-mold based molding method for micro-optical elements on planar and non-planar substrates is proposed. • The micro-structures on planar surfaces can be precisely transferred onto a flexible metallic mold. • The geometrical accuracy and surface roughness of the molded sample is obtained. • Unlike the conventional polymer-based flexible mold, this method can be widely used in elevated temperature (up to 1,000℃). [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the effect of bis [3(triethoxysilyl) propyl] tetrasulfide (Si69) and 3-Glycidoxypropyl trimethoxy silane (GPS) on the properties of unidirectional enset fiber reinforced Polypropylene (PP) composite. For this purpose, enset fiber was weaved into the mat and treated with 1.5 wt% Si69 and 5 wt% GPS after which it was used to reinforce PP composites through the film stacking method followed by the compression molding. Fabricated composites were characterized by their tensile, thermal, water absorption, image of the fracture surface, and FTIR spectroscopy properties. Among the developed unidirectional reinforced PP composite, the surface-treated enset-woven mat with 1.5wt% Si69 gave the highest tensile strength with an increase of 267.1%, and 36.9% from untreated enset random (EvRa) and unidirectional fiber-reinforced PP composite (EvUnt) respectively. Moreover, 1.5 wt% Si69-treated enset fiber unidirectional reinforced PP composite reduced equilibrium water uptake percentage by approximately two folds, and thermal performance also improved by 12.9% from EvUnt composite. Notably, both silane treatment of enset fibers and composites increased elongation at break compared to EvUnt. Altogether, 1.5wt% Si69-treated enset fiber unidirectional reinforced polypropylene composite achieved a remarkable improvement of property and can be used for high mechanical and long-term performance applications. [ABSTRACT FROM AUTHOR]

Waste poly(vinyl chloride) fill material from the cooling tower of a power plant was used for mechanical recycling. Mechanical recycling is the processing of plastic waste without changing the original chemical structure of the plastic. The waste rigid poly(vinyl chloride) fill material was cleaned, grinded and compression molded at optimized conditions of time, temperature and pressure using a compression molding machine. Virgin poly(vinyl chloride) was purchased and compression molded by the same compression molding machine. The compression molded sheets of waste poly(vinyl chloride) and virgin poly(vinyl chloride) were characterized by attenuated total reflection Fourier transform infrared analyses, tensile properties analyses, and thermal properties analyses. The results revealed that waste rigid poly(vinyl chloride) fill material is mechanically recyclable into new products such as pipes, profiles, furniture and other related products. [ABSTRACT FROM AUTHOR]

Present work attempted to manufacture kenaf/PLLA/HDPE blended composites using a novel technique of microwave-assisted compression molding (MACM). Since the manufacturing of pure PLLA composite is costly as well as its structural instability while manufacturing via MACM. Therefore, blending of HDPE in PLLA was done for structural stability as well as cost reduction purpose. Influence of microwave power and HDPE blend ratio on thermal and mechanical properties of 20 wt.% kenaf/PLLA/HDPE blended composites were investigated. Effect of various microwave power levels (i.e., 180 W, 360 W, and 540 W) and different HDPE blend percentages (i.e., 0%, 10%, 20%, 30%, and 40%) on mechanical properties of PLLA-based composites studied. Composites fabricated at 180 W and 30% HDPE blend exhibited the highest tensile strength. Elongation of composites decreased at higher microwave power due to decreased relaxation time of molecules. Furthermore, the crystallinity of the composites increased with increasing wt.% of the HDPE blend. [ABSTRACT FROM AUTHOR]

Snake grass fibers (SGFs)-reinforced polypropylene (PP)-based longitudinal bio-composites (40 wt% by fiber) were successfully manufactured by compression molding and tested for their physicomechanical, hardness, and thermal properties. SGFs were modified with non-ionizing radiation at different intensities and then bio-composites were fabricated. The mechanical properties of irradiated-SGF/PP bio-composites were significantly improved compared to untreated parts. Irradiated SGFs were grafted with 2-hydroxyethyl methacrylate (HEMA) monomers by photocuring under UV light. The number of UV passes and therefore the HEMA concentration were optimized with the extent of grafting of HEMA, tensile, and impact properties. Bio-composites reinforced with 10% HEMA and the 50th UV pass of SGF show maximum mechanical properties. Again, the irradiated SGFs were modified with alkali (NaOH) solutions of different concentrations at different temperatures. Optimized alkali-treated SGFs were then grafted with optimized HEMA by photocured with the same UV-pass and their composite samples rendered the best mechanical properties like tensile strength, tensile modulus, impact strength, and hardness. Optimized alkali-treated SGF with optimized HEMA grafted composite samples had higher thermal stability than other samples. Scanning electron microscopy, water absorption, and weather tests of composites were also investigated. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) is the most popular thermoplastic biopolymer providing a stiffness and strength alternative to fossil-based plastics. It is also the most promising biodegradable polymer on the market right now, thus gaining a substitute for conservative artificial polymers. Therefore, the current research focuses on synthesizing and mechanical characterization of particle-reinforced PLA composites. The hot compression molding technique was used to fabricate PLA-based composites with 0, 2.5, 5, and 7.5 weight % of sawdust, rice husk, and bagasse particle reinforcements to enhance the performance of the PLA. The pellets of PLA matrix were taken with an average size of 3 mm and particle reinforcements of an average size of 50 µm were used as the raw materials. After processing the PLA composites, microstructural and mechanical characterization studies were carried out to check the uniform distribution of the reinforced particles on the PLA matrix and the improvement in their strength, respectively. The results found hardness varied from 29.7 to 36.1 Shore D, tensile strength from 46.2 to 62.5 MPa, impact strength from 14.5 to 17.4 kJ/m² and flexural strength from 78.9 to 93 MPa from all processed composites. In addition, SEM images were taken to perform a microstructural evaluation of the PMCs. was observed on the composites with a reinforcement of 7.5%, and hence it showed lesser performance. Moreover, PLA with 5% rice husk particle reinforcement showed superior performances compared with other reinforcements. [ABSTRACT FROM AUTHOR]

The interest in recycled carbon fiber (rCF) is growing rapidly and the supply chain for these materials is gradually being established. However, the processing routes, material intermediates and properties of rCF composites are less understood for designers to adopt them into practice. This paper provides a practical pathway for rCFs in conjunction with low cost and, for the most part, commodity thermoplastic resins, namely polyethylene (PE), polyamide 66 (PA66) and polyethylene terephthalate (PET). Industrially relevant wet-laid (WL) process routes have been adopted to produce mats using two variants of WL mats, namely (a) high speed wet-laid inclined wire to produce broad good 'roll' forms and (b) 3DEPTM process patented by Materials Innovation Technologies (MIT)-recycled carbon fiber (RCF), now Carbon Conversions, which involves mixing fibers and water and depositing the fibers on a water-immersed mold. These are referred to as 'sheet' forms. The produced mats were evaluated for their processing into composites as 'fully consolidated mats' and 'non-consolidated' as-produced mats. Comprehensive mechanical data in terms of tensile strength, tensile modulus and impact toughness for rCF C/PE, C/PA66 and C/PET are presented. The work is of high value to sustainable composite designers and modelers. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the physical, mechanical, morphological, structural, and thermal properties of polylactic acid (PLA) and polyhydroxybutyrate (PHB) biopolymer composites reinforced with thermally treated wood flour and to determine the formulations having optimum properties by using multi-criteria decision-making (MCDM) methods. As a filler, Scots pine wood flour (untreated and thermally treated at 212 °C) was used at the loading rates of 10% and 30%. The samples were prepared using a twin-screw extruder and then by compression molding. The results showed that the addition of both thermally treated and untreated wood flour slightly increased the density of the composites. According to the color measurement, the thermally treated wood composites were slightly darkened in appearance. In the composites, with both wood fillers, the water absorption and thickness swelling ratios had increased during the 20–250 days of water exposure. Lower water absorption and thickness swelling rates were found for the composites with thermally treated wood filler compared to the other composites. The wood fillers generally lowered the mechanical properties of the PLA and PLA/PHB composites, with the PHB composites as the exception. However, the tensile modulus and Izod impact strength of the composites generally increased with the addition of wood fillers. Morphological examination performed by scanning electron microscopy (SEM) indicated that the wood flour was mostly homogeneously distributed in the matrix, which improved the mechanical properties of the composites. Thermogravimetric analysis (TGA) showed that the addition of wood filler to the neat biopolymers as a rule did not provide significant improvement in the thermal stability; however, the fillers increased the thermal stability of neat PHB. The Fourier-transform infrared (FTIR) spectroscopy detected no differences in the chemical structure of the composites. The X-ray diffraction (XRD) results indicated a general increase in the crystallinity with the addition of wood fillers to the neat biopolymers and the blends. All the findings were subjected to MCDM analysis to determine the formulation having the optimum properties and the results showed this to be the neat PLA sample. [ABSTRACT FROM AUTHOR]

Polystyrene (PS)‐based and carbon fabric‐reinforced polymers (CFRPs) containing elastomer were prepared using the compression molding technique. PS was also reinforced with two types of carbon nanotubes (CNTs), as received and modified with a silane‐coupling agent. Nanocomposites were fabricated with two different methods, masterbatch dilution, and direct melt mixing. The effect of the nanocomposite preparation technique on the mechanical properties, electrical resistivity, and shape memory behavior of the multilayer composites was investigated. The tensile strength and tensile modulus of the multilayer composite containing CNTs modified with silane coupling agent, and prepared with masterbatch dilution method, increased by 33% and 34%, respectively, compared with the composites prepared with melt mixing. With the masterbatch dilution technique, the electrical resistivity was lower, and slightly increased with surface modification of CNTs. In both preparation techniques, the possible combined effect of CNTs and CF on the thermal and electrical conductivity of the composites led to 100% shape recovery lower than 30 s with electrically actuated bending test. [ABSTRACT FROM AUTHOR]

Unsaturated polyester resins (UPRs) are expansively used in different applications and recycling the significant amounts of UPR waste is still a universal problem. Vitrimerization is a feasible, environmental‐friendly, cost effective, and operative method, which can be used for recycling the crosslinked UPRs. In this method, the thermoset permanent network is changed into a dynamic network similar to the vitrimer‐type polymers. The results show that the existence of a transesterification catalyst in the system significantly enhances the efficiency of vitrimerization. The vitrimerized UPR thermosets can be reprocessed three times with mechanical properties comparable to the initial UPR. The results show that the excess of external hydroxyl groups in the system can prevent the formation of zinc ligand complexes in the network and consequently reduce the crosslinked density and mechanical properties of vitrimerized samples. The vitrimerized thermoset powder can be reprocessed through injection molding, extrusion, and compression molding which are conventional thermoplastic processing techniques. The unrecyclable UPR thermoset wastes can be recycled and reused through vitrimerization with the least loss in mechanical properties. [ABSTRACT FROM AUTHOR]

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[Display omitted] • Superhydrophilic and underwater superoleophobic stainless steel felt was developed. • The prepared felt showed tunable pore size and surface charge. • The surface charge of felt can induce the aggregation of oil droplets in water. • The felt can separate various emulsions stabilized by different surfactants. • Charge-induced demulsification was proposed to explain the performance of the felt. Oil-water mixtures, especially the surfactant-stabilized oil-in-water emulsions with high stability, are causing great difficulties in effective separation. In this work, a modification strategy was established to prepare functionalized stainless steel felt for emulsion separation by coating the felt with 3-triethoxysilylpropylamine, followed by the introduction of silica nanoparticles using a sulfur-based three-component coupling reaction. To satisfy the pore size requirement for effective emulsion separation, the developed felt was processed using a compression molding. With special wettability, optimized pore size, and electrostatic demulsification mechanism, the positive charged felt delivered outstanding separation capabilities for oil-in-water emulsions stabilized by various surfactants. Specifically, the flux and COD removal efficiency for the anionic-stabilized emulsion were up to 3911 L m-2h−1 and 95.3 %, while for cationic-stabilized emulsions, which were 1305 L m-2h−1 and 93.1 %. Our comparative results indicated that surface charges played an essential role in governing the separation performance of the felt, and the demulsification arising from the electrostatic attraction demonstrated better separation capability than that caused by the electrostatic repulsion. In addition, the developed felt showed controlled surface charge and anti-fouling performance under cyclic operations. The findings of this study are beneficial for constructing separation material with high separation efficiency and long-term durability for practical applications. [ABSTRACT FROM AUTHOR]

A novel additive manufacturing (AM) methodology combined with a compression molding (CM) process has been previously developed to optimize the microstructure of short fiber thermoplastic (SFTs) composites with higher fiber alignment and lower porosity, yielding superior stiffness, strength, and structural integrity. The current work examines the efficacy of the 'passive' infrared thermography (IRT) techniques for rapid fatigue characterization of SFTs that use the surface temperature evolution during cyclic loading due to self-heating as a fatigue indicator. A comparison of fatigue limits obtained from traditional stress-life (SN) (≈ 53. 1 % σ u t s ) and IRT (≈ 54. 1 % σ u t s ) shows a close match. However, the SN curve required 18 specimens and two weeks of continuous cyclic testing, while IRT used three specimens with 5 h of testing. Thus, the IRT approach provides an accelerated testing framework for rapidly estimating the fatigue limit. Additionally, existing phenomenological approaches to IRT fatigue characterization have been examined. [ABSTRACT FROM AUTHOR]

Natural fiber composites are widely used in a several industrial applications due to their outstanding biodegradability and recyclability. Thermal compression molding is a rapid and easy method to fabricate composite sheets. To better understand the manufacturing process and evaluate the mechanical properties of hemp woven fabrics reinforced thermoplastic composite at elevated temperatures, a detailed investigation is required. In this study, composite sheets were initially fabricated using hemp fiber fabrics (taffeta and serge 2×1) and polypropylene sheets by the thermal compression molding process. Mechanical tests (uniaxial, shear, and biaxial) were carried out at temperatures ranging from 20 to 160 ∘C in order to estimate the mechanical properties of composite sheets. Non-linear behavior was observed during the loading due to the unbalanced weaving pattern of hemp fabric. The biaxial behavior of the composite was estimated using a theoretical method for fabric strength prediction taking into account the interaction effect between the yarns. The experimental results demonstrate that, at high temperature, the polymer softens and the fiber reinforcements dismantle which resulting in a decrease in the mechanical properties of the composite. Two analytical models (Ha & Springer and thermal expansion coefficient) were also proposed to estimate the thermo-mechanical properties of natural fiber composites subjected to various temperatures.

[Display omitted] • First demonstration of catalyst-free, biobased, non-isocyanate polythiourethane foam. • Homogeneous foaming by matching disulfide crosslink formation rate with foaming rate. • Achieving a range of foam characteristics by tuning the reactants and blowing agent. • Highly dynamic disulfide exchange enabling catalyst-free, fast foam-to-film recycling. • First demonstration of catalyst-free refoaming by pseudo-injection molding. We have developed a series of reprocessable, re-foamable, biobased, catalyst-free non-isocyanate polythiourethane (NIPTU) network foams crosslinked via the auto-oxidation of the pendant thiol groups into disulfides. Capitalizing on the interplay of fast ring-opening of cyclic thiocabonate to create linear backbones and slightly slower thiol auto-oxidation to create disulfide crosslinks, the gelling reaction synchronized well with the vaporization of the physical blowing agent. Different physical blowing agents were used to achieve facile tunability of morphological and physical properties. In addition, incorporating a small amount of trifunctional crosslinker significantly enhanced the compressive mechanical properties of the foam. Moreover, we leveraged the rapid and catalyst-free disulfide dynamic exchange to achieve both reprocessability and extrudability of the NIPTU foams. We demonstrated that the foams are intrinsically self-healable and reprocessable by compression molding. We observed rapid stress relaxation at temperatures above 160 °C, prompting us to explore continuous processing techniques like extrusion and pseudo - injection molding. Spent foams can be extruded into bulk films at 180 °C with excellent property retention. Additionally, with our NIPTU system we demonstrated, for the first time, foam-to-foam recycling of non-isocyanate polyurethanes. By adding a small amount of sodium bicarbonate blowing agent into the spent foams prior to extrusion, CO 2 gas was generated during extrusion, leading to a cellular structure. This work highlights the advantages of NIPTU foams: the catalyst-free, rapid synthesis of foams and property tunability, self-healing capability, and amenability towards a family of reprocessing techniques including compression molding, extrusion into bulk films, and foam-to-foam extrusion. [ABSTRACT FROM AUTHOR]

Recycling and reuse of textile waste is a proficient solution in preventing waste going into landfill and causing pollution. This paper reports the use of microdust generated from fibers in textile spinning mills to fabricate composites using compression molding for prospective applications in the building sector. Ten composite samples of 6 mm and 10 mm were developed by changing the microdust-resin blend proportions ranging resin content of 30%–10%. The tensile, flexural and compression properties, fire retardancy, water absorption and the insulation properties of the composites were determined. The results showed that the 6 mm thick composite board with 70% microdust had the most desired mechanical properties with tensile strength of 6.41 MPa, compressive strength of 3.6 MPa, and flexural strength of 10.2 MPa. These properties are superior compared to commercially available false ceiling board made of gypsum material of similar density and thickness. The thermal insulation value was 0.117 m2 K/W which is equivalent to the commercial sample (0.102 m2 K/W) used in similar applications in the building industry. The sample with 80% microdust (10 mm thick) achieved the highest thermal resistance (0.1879 m2 K/W) which is about 50 % higher than a commercial sample of the same thickness. This study shows that the composite panels overall are comparable to the commercially available panel used in the building industry and provides cost effective and sustainable alternatives for thermal barrier panels while overcoming the issue of landing filling of microdust from the spinning mills. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Developed compression molding monitoring system reveals cure shrinkage behavior of epoxy molding compound in curing stages. • FEA considering viscoelastic properties and cure shrinkage accurately predicts warpage behavior of bi-material dummy package. • Optimized post-cure temperature profile reduces bi-material dummy package warpage threefold, enhancing package reliability. Warpage in semiconductor packages is a critical issue that affects their reliability and performance. This study aims to minimize the warpage of a bi-material dummy package by optimizing the post-mold curing (PMC) temperature profile. A warpage simulation model was developed considering the viscoelastic properties and cure shrinkage behavior of the epoxy molding compound (EMC). A compression molding monitoring system was also developed to analyze the cure behavior of the EMC. The gelation point of the EMC during compression molding was determined using a dielectric sensor, while cure shrinkage behaviors were analyzed using a fiber Bragg grating sensor. Viscoelastic properties were characterized through stress relaxation tests, and thermal properties were measured using three-dimensional digital image correlation. The developed simulation model was used to optimize the PMC temperature profile using a genetic algorithm. Experimental validation showed that the optimized temperature profile reduced the warpage from ∼1519 μm to 486 μm compared to a linear profile. The findings of this study have broader implications for the design and manufacturing of semiconductor packages, as the proposed approach can be applied to minimize warpage and improve package reliability. [ABSTRACT FROM AUTHOR]

For the production of lightweight, eco-friendly, and incredibly robust products, hybrid bio-epoxy composites stand out as an outstanding material choice in the manufacturing sector. This study focused on creating a composite, where in the epoxy resin infused with microcellulose fillers is reinforced by stacking four layers of basalt-jute-jute-basalt woven mats. The composite was made through the hand lay-up process, followed by the meticulous process of compression molding. The inclusion of microcellulose, sourced from the leaves of the Musa paradisiaca plant (MPPL), was a key component. The extraction of microcellulose from the MPPL involves alkali treatment, acid hydrolysis, bleaching, and slow pyrolysis. This micro cellulose was introduced to the layered composite in varying proportions (ranging from 0 % to 10 %). Subsequently, we carried out comprehensive tests in line with ASTM standards to assess the material's effectiveness with regard to thermo-mechanical properties and water absorption characteristics. The outcomes of these evaluations highlighted that the composite featuring a 5 % Musa paradisiaca plant leaf micro cellulose content within the basalt-jute-jute-basalt layers exhibited notably superior attributes in tensile strength (99.74 MPa), flexural strength (77.87 MPa), impact strength (40.27 kJ/m2), hardness (97 HRRW), and crystallinity index of 6.3 %. Furthermore, our investigation extended to the analysis of fractural morphology to understand the bonding behaviour and fracture patterns within the composite. • Basalt and Jute fabrics with agro waste based microcrystalline cellulose reinforced Composites properties were studied. • FTIR results confirmed the presence of cellulose Materials. • Thermal analysis revealed that this novel Composites have moderate thermal stability. • Mechanical properties ensured the possibility to use this Materials for lightweight applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Vitrimers are made from two renewable resources, lignin and epoxidized linseed oil. • Bio-based vitrimer composites are described as new green adhesives. • Vitrimers have shear lap strengths of about 10–17 MPa. • Bio-based adhesives are reprocessable, reweldable and biodegradable. The market of epoxy resin-based adhesives is constantly growing in the automotive, electronics, and healthcare industries thanks to their unique features such as high bonding strength, durability, and corrosion resistance. In this work, alternative sustainable vitrimer adhesives, containing from 20 to 50 wt% of lignin microparticles, were prepared from epoxidized linseed oil (ELO) and a boronic ester dithiol crosslinker (DBEDT), in the absence of solvents and catalysts. The addition of unmodified commercial Kraft lignin to the composites directly influences their thermal and mechanical properties and determines their bonding capacity between several adherent substrates, also affecting the rewelding potential. The lignin-vitrimer composites and the corresponding neat vitrimer matrix exhibited values of lap shear strengths in the range of 9 to 17 MPa, when tested as adhesives with aluminum, stainless steel, and wood specimens, and good to excellent rewelding capability. The amount of lignin microparticles influences the balance between cohesive and adhesive forces during the separation of the adhered aluminum surfaces and the eventual joint failure. In the case of the composites with 20 wt% of lignin, lap shear strength remains constant even after four cycles of rebonding via compression molding, indicating that the best rewelding performance is associated with previous cohesive failure when the adhesive remains on both aluminum sheets' surfaces. In addition, the adhesion was preserved for 83 % of the initial value after 24 h immersed in water. Importantly, biodegradability in both soil and seawater was enhanced by the presence of the lignin filler. In summary, the simple preparation strategy of bio-based vitrimer composites coming from two natural sources could pave the way to green alternatives for industrial applications, such as epoxy-based adhesives. [ABSTRACT FROM AUTHOR]

This study presents a novel approach to manufacturing carbon fiber and carbon nanotube-reinforced PEEK hybrid composites (CF/CNT/PEEK) using compression molding. The hybrid composite characteristics were compared with those of a control composite (CF/PEEK). Various tests were conducted on both composite types to investigate the impact of incorporating a carbon nanotube sock layer (an ultra-thin layer of a low-density CNT network), including three-point bend, electrical conductivity, and EMI shielding. The research also underscored the importance of EMI shielding simulation. An important aspect of the study involved performing multiscale simulations on control and hybrid composites, employing a digital twin methodology, and validating the results with experimental findings. For the hybrid composite, double multiscale simulations were performed by integrating two local-scale models, a CF/PEEK unit cell (micro-scale) and a CNT/PEEK representative volume element (RVE) (nano-scale), into a global-scale model. A detailed post-processing analysis of the simulation results was conducted to analyze stress distribution on local and global scale models. It was noted that there was an over 8 % increase in the flexural strength of the hybrid composite, along with a reduction of over 27 % in the standard deviation of the results. The introduction of CNTs enhanced the electrical conductivity by more than 36 %. It conferred remarkable EMI shielding effectiveness exceeding 50 dB across the entire X-band frequency range, attributed to enhanced reflection and absorption. EMI shielding simulations suggest that refining the manufacturing process of the hybrid composite could enhance its shielding properties. The developed multiscale simulation has been demonstrated as an efficient prediction tool, as the simulation outcomes closely align with experimental findings. The resultant hybrid composite is promising for potential multifunctional applications. [ABSTRACT FROM AUTHOR]

Vitrimers are thermally reversible crosslinked polymers that combine the performance of thermosets with the benefits of melt (re)processing. However, existing high-storage modulus vitrimers lack this melt-reprocessibility. This study reports on high storage modulus vitrimers obtained by grafting vinyltrimethoxysilane onto high-density polyethylene (HDPE) using silyl ether crosslinker, bis[3-(trimethoxysilyl)propyl]amine. We also explored the effects of 2,2,6,6-tetramethyl-4-piperidinol and diethyl maleate on the performance of these vitrimers. All vitrimers reported herein are prepared in one step via melt-extrusion without the use of any solvent or catalyst. These vitrimers were characterized via differential scanning calorimetry, Fourier-transform infrared spectroscopy, thermogravimetric analysis, dynamic mechanical analysis and mechanical testing. Selected vitrimers were melt-reprocessed six times and assessed for changes in their storage modulus and mechanical strength by industry-relevant extrusion processing. This study is the first of its kind to offer a solvent-free, single-step approach for the synthesis of vitrimers from HDPE. These vitrimers exhibit an impact strength five times higher relative to that of conventional HDPE, a very high storage modulus (1.58 MPa) at 180oC, and full melt-reprocessability. Considering that extrusion and injection molding is used, the storage modulus achieved in this study is significantly higher than that of vitrimers generated by compression molding, which is commonly used in previous research. [Display omitted] • Demonstrated high storage modulus silyl ether HDPE vitrimers. • Investigated TEMPO and diethyl maleate effect on vitrimers performance. • A solvent-free, single-step approach for preparing silyl ether-based HDPE vitrimers. [ABSTRACT FROM AUTHOR]

A green, efficient preparation and high-value recycling of cardanol-based polyurethane (CPU) foams from cashew raw materials has been achieved. Cardanol-based polyphenols are synthesized by Friedel-Crafts alkylation of cardanol and guaiacol. The resulting polyphenols can be used as precursors to produce renewable CPU foams, which have excellent properties and serve as sustainable alternatives to traditional PU. CPU foams containing phenol-carbamate bonds can be reprocessed into CPU films that have adjustable mechanical properties and can undergo multiple reprocessing cycles. Using a simple compression molding process, cashew shell waste and CPU foams can be fused to form CPU-Wood films with repairability, reprocessibility and reshaping properties. [Display omitted] • Cardanol-based polyphenols were prepared by Friedel-Crafts alkylation. • Cardanol-based polyurethane (CPU) foam were made from cardanol-based polyphenols. • The CPU foam could be processed into CPU films through thermal compression molding. • Wood-plastic films were produced using CPU foam and cashew shell as the matrix. The economic processing, sustainable recycling, and environmentally friendly application of polyurethane (PU) foams are important issues that need to be addressed urgently. In this study, we propose a strategy for the comprehensive utilization of cardanol and cashew shells to design cardanol-based PU (CPU) foams and wood-plastic films that can be recycled and reused. Firstly, cardanol-based polyphenols (CBPs) with a phenolic hydroxyl content of 3.29 mmol/g were prepared by Friedel-Crafts alkylation reaction using cardanol and guaiacol as raw materials. Subsequently, CPU foams were prepared by reacting CBPs with isocyanate, and the vertical and parallel compressive strengths could reach up to 0.27 MPa and 0.32 MPa, respectively, when the addition of CBPs was 80 %. These CPU foams, containing dynamic phenol-carbamate bonds, could be hot-pressed into transparent and smooth CPU films with tensile strengths of up to 30.5 MPa and could be re-formed at least three times. Finally, CPU foam and cashew shell waste were mixed and hot-pressed to produce a green wood-plastic composite with a tensile strength of up to 38.8 MPa. The resulting CPU-Wood films could be repaired or reshaped at least five times (38.0 MPa and 38.1 MPa) and could be formed into various shapes. This research paves the way for large-scale industrial production of recyclable and regenerative bio-based foams, making effective use of waste materials to achieve environmentally friendly production processes. [ABSTRACT FROM AUTHOR]

• The virtual fabric model can be used for the simulation of actual weaving process. • Virtual fabric composed of truss elements predicts the microstructure of 3D woven fabric. • Friction and yarn tension affect the trajectory and cross-sectional shape of the yarn. • The intersection-induced tension between warp and weft yarn causes fabric deformation. • The corners of the mold induce the interlayer slippage of fabric and alter the trajectory of the warp yarns. This article introduces a modeling method aimed at predicting the internal geometric structure of 3D warp interlock fabric. Inspired by the digital element method, the method employs truss elements to model the yarns as fiber bundles, and considers their material properties. This technique allows for predicting the microstructure of 3D woven fabric based on simple input characteristics. By varying the elastic modulus of virtual fibers, the friction coefficient between fibers, and the tension load at the ends of yarns, and designing compression molding molds to compress the fabric into shape, the virtual fiber fabric predicted the influence of variables on the fabric. The study found that the structure of the samples obtained through CT scanning is generally consistent with the structure of the virtual fiber fabric. The elastic modulus has a relatively minor impact on the fabric structure, whereas the friction coefficient and tension load significantly affect the cross-sectional shape of the yarns. During compression molding, deformation within the mold leads to interlayer fabric slippage and changes in the cross-sectional shape of the fabric. This suggests the feasibility and applicability of virtual simulation testing methods for analyzing the behavior of various types of 3D woven fabrics. [ABSTRACT FROM AUTHOR]

Efficiently thermal management in electronic devices calls for creating polymer composites that have superior thermal transport abilities. Compared with single-filler composites, hybrid-filler composites have gained significant attention as they not only utilize the advantages of each filler individually but also allow for the potential cooperation in constructing filler networks between them. Differing from the previous research on hybrid-filler size, geometry, composition, and content and their impact on thermal conductivity (TC) in composites, this study aims to examine the spatial distribution effects of hybrid-fillers. A binary-filler strategy comprising of anisotropic 2D h- BN and 0D isotropic S–Al 2 O 3 has been proposed, with the primary h -BN filler aligned to filly utilize its anisotropy and intrinsic TC properties. Furthermore, positioning a small quantity of S–Al 2 O 3 between adjacent parallel h -BN considerably improves TC in the non-oriented direction of silicon rubber (SiR) composites. A special focus is given to the influence of the interstitial S–Al 2 O 3 filler on the individual through-plane TC (λ ⊥) and in-plane TC (λ ⫽) variation of the binary-filler hybrid SiR composites, which are perpendicular and parallel to the oriented h -BN. When incorporating 40 vol% h -BN and 5 vol% S–Al 2 O 3 , the binary SiR composites exhibit the highest concurrent λ ⫽ and λ ⊥ values of 14.581 and 2.132 W/m·K, respectively. The corresponding effects on the ductility, hardness, and dielectric properties of the SiR composites were explained. Moreover, the use of commercially available TC fillers, along with the effortless preparation method, enables the potential to produce h -BN based TIMs materials on a large scale for thermal management usage. [Display omitted] • A binary filler system consisting in-plane oriented 2D h -BN and 0D isotropic S–Al 2 O 3 is designed. • The addition of S–Al 2 O 3 filler between adjacent parallel h -BN flakes facilitates vertical heat transfer. • The binary structure of h -BN/S–Al 2 O 3 exhibits an anisotropic feature in the filler contact thermal resistances. • The binary filler strategy mitigates the trade-off between in-plane and through-plane thermal conductivity. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT) heat absorbers were developed to enhance the direct solar heating of liquid tin as a heat-transfer fluid in ground solar receivers. To improve the thermal transfer of absorbed solar energy to tin, absorbers reinforced with carbon black (CB) were fabricated by compression molding. As the compressive strength increased, the CNT absorber formed denser nanotube arrays, which increased the thermal conductivity by 1.68 times. Increasing the CB content further enhanced the conductivity by 1.19 times through grape cluster-like structures. The thermal properties of CNT absorbers predominantly depend on the compressive strength and CB content, and a correlation is proposed for predicting the conductivity. The most effective absorber was prepared at 50 kPa with a CB/CNT ratio of 1.0. The heat absorption characteristics of the solar receivers (50 mm i. d., 60 mm high) with the prepared CNT absorbers were determined. Tin temperatures with CNT absorbers rose more steeply than in bare tin systems, exhibiting a higher temperature increase per irradiance. The efficiency of the bare tin system improved from 24.8 % to 45.4 % using absorbers at 50 kPa and to 46.4 % using a CB/CNT ratio of 0.75 at 20 kPa. Under wind-free conditions, the receiver with the highest thermal conductivity achieved 67.7 % efficiency, a 1.69-fold increase over a tin-only receiver. This study confirmed that the improved thermal conductivity of the CNT absorbers significantly enhanced the receiver efficiency by facilitating rapid solar-energy transfer to liquid tin. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Effects of high temperature and high humidity on copper/epoxy bond were studied in nanoscale. • Experiments and auxiliary molecular dynamics simulations were performed. • The water absorbed in the epoxy caused complex physical and chemical changes at the copper/epoxy interface. • The crystal orientation of cuprous oxide significantly influenced its bonding with epoxy. • The higher bonding strength is not equal to the higher reliability. Epoxy encapsulation is a promising technique to reduce the size of the power module. Its reliability is a key aspect. Many previous studies developed new epoxy materials or new surface treatment methods to improve reliability. However, reliability mechanisms are still not well understood. This study focused on the reliability of copper/epoxy bonds under high temperature and high humidity conditions because previous studies did not reach a unified conclusion on this issue. The copper/epoxy bonds are fabricated by compression molding. Then, these copper/epoxy bonds are placed in the 85 ℃/85 %RH reliability test for 1000 h. The bonding strength change was measured. Surprisingly, the bonding strength between copper and epoxy increased after the 85 ℃/85 %RH reliability test. The possible reason was investigated by observing the fracture surface and bonding interface in a nanoscale. In addition, molecular dynamics simulations were performed to better understand the experimental results. The results showed that the water absorbed in the epoxy caused complex physical and chemical changes at the copper/epoxy interface. The formation of a new cuprous oxidation layer with aligned crystal orientation is supposed to be the reason for the bonding strength increase. Our findings will provide a better understanding of copper/epoxy bonds. [ABSTRACT FROM AUTHOR]

The compression molding performance of a substrate block has a significant effect on the quality and stability of mechanical transplanting. The physical experiment and DEM simulation were combined to evaluate the compression molding behavior of substrate block in this study. A calibration procedure of DEM parameters of peat particles was proposed at first. Then, the above parameters were brought into the contact model of the compression system–particles, and the effect of the loading speed on the compression behavior of the peat substrate block was investigated. The compressive force–displacement curves of the simulated and measured tests were all contained in the initial linear stage and non-linear stiffing stage. The particle number of central sections was higher than side section, and the variable coefficient was greater at higher loading speed. The substrate blocks all expanded after demolding. The higher the loading speed, the greater the expansion in the height’s direction, and the easier it was for cracks to be generated near the bottom. This study will provide a reference for the design of substrate block forming machines.

This study aims to explore the compression forming of greening substrate bricks, covering the raw material preparation, pressing procedure, bricks characterization, finite element method (FEM) simulation, and the parameter optimization. 1) Raw material preparation: The rice straw was crushed by the grinder to mix with the cow dung. The aerobic fermentation was adopted to be completely decomposed the materials. Among them, the premixed materials was hold by hand and molded for reserve. Polyacrylic acid sodium, insecticide and fungicide were mixed to dissolve as the premixed liquid. The premixed materials and liquid were mixed in the proportion for the raw material of greening substrate bricks. 2) Pressing procedure: A pressing process of three-layer composite was utilized to make the greening substrate bricks. Among them, three layers was in the middle, including the upper and lower matrix layer, as well as the greening substrate layer. The greening substrate brick was made and dried below 60 ℃ for the subsequent transportation and storage. 3) Bricks characterization: The physical properties were characterized for the greening substrate bricks after molding and drying. Specifically, the bulk density, the total porosity, and the aeration porosity were 0.62 g/cm³, 63.09%, and 27.78%, respectively. The material properties of greening substrate brick were fully met the needs of plant growth, such as the bulk density and porosity. The physical and chemical indexes were within a reasonable range (pH=7) to balance the nutrition of greening substrate brick. 4) FEM simulation: A three-dimensional numerical model was established, where the materials to be compressed and naturally stacked in the forming mold were selected as the research objects. A systematic investigation was made to determine the variation in the stress along the height during compression and extrusion at different times. The distribution of compression stress was found: the extrusion pressure and friction force, the inner wall of the forming die produced the radial pressure on the material. The material was first extruded from the upper and outer layers to the central layer, and then flowed to the lower layer. 5) Parameter optimization: A pore channel model was constructed to determine the internal pore connectivity and dynamic water migration during compression. A pore channel and a skeleton were included, where the former was a solid matrix bonded and wound by the rice straw and cow dung, while, the pore channel included the channels and blind channels with the divergence and permeability. The compression molding of greening substrate brick was divided into the loose, compaction, pressure maintaining, combined with the pore channel model. It was verified the relationship between the pore coefficient ratio of the model and the porosity of the greening substrate brick after molding with the different holding time, indicating that the holding time posed an important influence on the compression molding. The longer the holding time was, the better the compression molding and molding stability were, particularly with the reduced total porosity. 6) The optimal molding process parameters of greening substrate brick were achieved using the single factor test method. Specifically, the moisture content of materials, compression time, compression stress, and cow dung mass percentage were taken as the experimental factors, whereas, the drying time, water absorption after drying and destructive strength were taken as experimental indexes. An optimal combination was achieved, where the moisture content was 60.4%-80.8%, the compression stress was 0.17-0.33 MPa, the compression time was 2-4 min, and the mass percentage of cow dung was 20%-40%. A four-element quadratic orthogonal rotation combination test was designed for the variance analysis and response surface analysis using Design-Expert 12.0 and Excel 2016 software. The optimal parameters were as follows: the moisture content of material was 75.7%, the compression stress was 0.29 MPa, the compression time was 2.5min, the mass percentage of cow dung was 30%, the drying time of greening substrate brick was 656.9 min, the water absorption after drying was 74%, and the destructive strength after drying was 11.8 N. The forming and cultivation tests were conducted to verify the optimal parameters. The germination rate of greening substrate brick was maintained at 88%, and the number of repeated water absorption was more than 50 times. The plant grew well and the root system was developed, which met the requirements of normal growth and development of plants. This finding can provide a strong reference for the production of greening substrate bricks, the comprehensive utilization of agricultural organic wastes for the upgrading of urban greening products. [ABSTRACT FROM AUTHOR]

Milled waste feathers and chopped kenaf short fibers were used as the matrix resin and reinforcements, respectively, and the production of totally bio-based composites was attempted via hot-press compression molding, changing the fiber content and/or fiber length of the kenaf fibers to optimize the properties. The tensile strength of the composites increased with increasing the fiber content at first. However, the increase of the tensile strength of the composites leveled off and then decreased over the fiber content of 30 wt% due to the occurrence of insufficient filling of the matrix feather resin around the fibers which, we suggest, was due to the low fluidity of the feathers during the molding. However, the thermal stability could be enhanced when the fiber content was set at over 50 wt%. The increase of the loss modulus, E″, of the composites in the temperature range above the softening temperature of the feather resin was greatly suppressed, and E″ became almost unchanged, even at 200 °C, when the fiber content was set at 60 wt%. [ABSTRACT FROM AUTHOR]

Biodegradable Mater-Bi (MB) composites reinforced with hazelnut shell (HS) powder were prepared in a co-rotating twin-screw extruder followed by compression molding and injection molding. The effects of reinforcement on the morphology, static and dynamic mechanical properties, and thermal and rheological properties of MB/HS biocomposites were studied. Rheological tests showed that the incorporation of HS significantly increased the viscosity of composites with non-Newtonian behavior at low frequencies. On the other hand, a scanning electron microscope (SEM) examination revealed poor interfacial adhesion between the matrix and the filler. The thermal property results indicated that HS could act as a nucleating agent to promote the crystallization properties of biocomposites. Furthermore, the experimental results indicated that the addition of HS led to a significant improvement in the thermomechanical stability of the composites. This paper demonstrates that the incorporation of a low-cost waste product, such as hazelnut shells, is a practical way to produce low-cost biocomposites with good properties. With a content of HS of 10%, a remarkable improvement in the elastic modulus and impact strength was observed in both compression and injection-molded samples. With a higher content of HS, however, the processability in injection molding was strongly worsened. [ABSTRACT FROM AUTHOR]

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Phase change microcapsule/diatomite composite was prepared by using n-octadecane phase change microcapsule as heat storage materials. Phase change microcapsule/diatomite thermal storage plate (TSP) was prepared by compression molding. Differential scanning calorimeter, scanning electron microscope and fourier infrared spectrometer have been used to test and analyze the properties of composite materials. The thermal conductivity of the thermal storage plate was tested, the heat storage and release performance of the thermal storage plate was tested, and its heat storage performance was analyzed. It is concluded that: the melting and solidification temperatures of the phase change microcapsule/diatomite composite material are 25.64°C; and 24.04°C;, respectively, and the latent heat of melting and solidification are 59.51 J/g and 56.97 J/g, respectively. The TSP has obvious hysteresis in the temperature change, and helps to adjust the indoor temperature balance. [ABSTRACT FROM AUTHOR]

Recently, the natural fibers replaced the synthetic fibers to a great extent as reinforcement to the polymer composites. Among the natural fibers, coir fibers has the potential to be used in various applications because of its abundancy, non-toxicity, low cost, and resilient properties. Generally, the polymeric materials are very sensitive to the flame. That is why it is inevitable to measure the performance of the polymer composites prior to the applications such as construction, automotive parts, etc. Coir fibers have high lignin content that makes it a preferable reinforcement in the development of polymer composites to enhance the fire resistant properties. The aim of this work is to study the flammability properties of coir fibers reinforced polypropylene composites along with the thermal stability and mechanical properties. Composites were fabricated by melt compounding with micro-compounder followed by compression molding. The dynamic mechanical properties were analyzed. The storage modulus of coir/polypropylene composites was found to be increased than the neat polypropylene but the damping properties of the composites were decreased. The flammability properties have been studied using horizontal burning test by UL-94. It is observed from the study that the composites with 30 wt% of coir fibers content achieved V-0 rating. The flame propagation speed increased for composites up to 20 wt% of coir fibers content and after that it was decreased. The thermal stability of the composites was found to be increased with the increase in fiber loading. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)