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The wet-laid process with flax (base) and polypropylene (binder) fibers has been used to obtain nonwovens for further processing by hot-press molding. Mechanical characterization of nonwovens has revealed that slight anisotropy is obtained with the wet-laid process as better tensile strength is obtained in the preferential deposition direction. The thermo-bonding process provides good cohesion to nonwovens, which is critical for further handling/shaping by hot-press molding. Flax:PP composites have been processed by stacking eight individual flax:PP nonwoven sheets and applying moderate temperature and pressure. As the amount of binder fiber is relatively low (< 30 wt%) if compared with similar systems processed by extrusion and injection molding, it is possible to obtain eco-friendly composites as the total content on natural fiber (flax) is higher than 70 wt%. Mechanical characterization of hot-pressed flax:PP composites has revealed high dependency of tensile and flexural strength on the total amount of binder fiber as this component is responsible for flax fiber embedment which is a critical parameter to ensure good fibermatrix interaction. Combination of wet-laid techniques with hot-press molding processes is interesting from both technical and environmental points of view as high natural fiber content composites with balanced properties can be obtained. POLYM. COMPOS., 2012. (c) 2011 Society of Plastics Engineers, This work is part of the project IPT-310000-2010-037, "ECOTEXCOMP: Research and development of textile structures useful as reinforcement of composite materials with marked ecological character" funded by the "Ministerio de Ciencia e Innovacion," with an aid of 189540.20 euros, within the "Plan Nacional de InvestigacionCientifica, Desarrollo e InnovacionTecnologica 2008-2011" and funded by the European Union through FEDER funds, Technology Fund 2007-2013, Operational Programme on R+D+i for and on behalf of the companies." It is also acknowledged the project "WET-TEX: Implementacion de la tecnologia wet-laid en el desarrollo de nuevos textiles medico-sanitario" with expedient number IMIDIC/2010/137 (total aid of 284400 euro), and the project "WET-TEX II: Implementacion de la tecnologia wet-laid en la investigacion y desarrollo de paneles para aplicaciones tecnicas a partir de residuos procedentes de la industria textil." with expedient number IMDEEA/2011/167 (total aid of 255000 euro) funded by IMPIVA and cofunded (80%) by the European Union through FEDER funds, Valencian Community Operational 2007-2012.

Effect of temperature on hygroscopic thickness swelling rate of lignocellolusic fillers/HDPE (high density polyethylene) composites was investigated. The composites were manufactured using a dry blend/hot press method. In this method, powder of plastic and dried powder of lignocellolusic material were mixed in high-speed mixer and then the mixed powder were pressed at 190°C. Lignocellolusic fillers/HDPE composites panels were made from virgin and recycled HDPE (as plastic) and wood sawdust and flour of rice hull (as filler) at 60% by weight filler loadings. Nominal density and dimensions of the panels were 1 g/cm3 and 35 × 35 × 1 cm3, respectively. Thickness swelling rate of manufactured wood plastic composites (WPCs) were evaluated by immersing them in water at 20, 40, and 60°C for reaching a certain value where no more thickness was swelled. A swelling model developed by Shi and Gardner [Compos. A, 37, 1276 (2006)] was used to study the thickness swelling process of WPCs, from which the parameter, swelling rate parameter, can be used to quantify the swelling rate. The results indicated that temperature has a significant effect on the swelling rate. The swelling rate increased as the temperature increased. The swelling model provided a good predictor of the hygroscopic swelling process of WPCs immersed in water at various temperatures. From the activation energy values calculated from the Arrhenius plots, the temperature had less effect on the thickness swelling rate for the composites including wood sawdust compared with the rice hull as filler and the composites including recycled compared with the virgin HDPE as plastic. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Bismaleimdes (BMI) and experimental polyimides were resin transfer molded into carbon fiber fabrics using a custom-built injection mold placed within a vacuum hot press. This represents the first time that the latter type of materials has been resin transfer molded. This is a critical stage in developing materials and processing methods for future aerospace applications, such as the High Speed Civil Transport (HSCT).

In the present study, a positive-pressure filtration method was proposed to prepare carbon nanotube buckypapers (CNT BPs) with desirable porosity and mechanical properties. The obtained BPs were then infiltrated with epoxy via vacuum-aided resin transfer molding (VARTM) process without the use of a solvent. Some of the impregnated composites were directly cured under a vacuum pressure. The others were put into a hot-press to cure under a higher pressure of 0.7 MPa. Results have shown that the tensile strength and modulus of the vacuum cured composites were obtained as 215 MPa and 13.3 GPa, whereas these two values could reach 319 MPa and 20.3 GPa, respectively, for the hot-press cured composites. The glass transition temperature of the hot-press cured composites was also improved by 7% compared with that of the vacuum cured composites. Furthermore, SEM observation revealed that the BPs were infiltrated well with epoxy and good interfacial bonding between CNTs and epoxy was obtained. This study has demonstrated that the random aligned CNT BPs reinforced epoxy composites possessing desirable mechanical properties can be fabricated by using conventional processes when the microstructure of the BPs is improved. POLYM. COMPOS., 2016. © 2016 Society of Plastics Engineers

This study is focused on forming a fibrous-zinc oxide/polyvinylidine fluoride (ZnO/PVDF) nanocomposite and characterizing its dielectric behavior. The nanocomposite is prepared in two steps. First, a network of nanoscale diameter ZnO fibers is produced by sintering electrospun PVA/Zinc Acetate fibers. Second, the ZnO fibrous nonwoven mat is sandwiched between two PVDF thermoplastic polymer films by hot-press casting. Scanning electron microscope images of the nanocomposite show that hot-press casting of the fibrous-ZnO network breaks the network up into short fibers. The in-plane distribution of the ZnO fillers (i.e., the short fibers) in the PVDF matrix appears to comply with that of the pristine ZnO fibers before hot-pressing, indicating that the fillers remain well-dispersed in the polymer matrix. To the authors' knowledge, the work reported herein is the first demonstration of the use of electrospinning to secure the dispersion and distribution of a network of inorganic fillers. Moreover, processing a fibrous-ZnO/PVDF flexible composite as described in this report would facilitate material handling and enable dielectric property measurement, in contrast to that on a fibrous mat of pure ZnO. Because of the high surface area of the short ZnO fibers and their polycrystalline structure, interfacial polarization is pronounced in the nanocomposite film. The dielectric constant is enhanced significantly-up to a factor of 10 at low frequencies compared to the dielectric constant of constituent materials (both bulk ZnO and PVDF), and up to a factor of two compared to a bulk-ZnO/PVDF composite. POLYM. COMPOS., 31:1003-1010, 2010. (C) 2009 Society of Plastics Engineers

© 2021 Society of Plastics Engineers.Thanks to their superior mechanical properties, polymer matrix composites have gained considerable importance. In order to improve the impact resistance of polymer matrix composite materials, a new hybrid material known as fiber metal laminate (FML) has been developed. The aim of this study was to reveal the effect of stacking sequence (SS), metal volume fraction (MVF), and number of layers on ballistic resistance in fiber metal laminates (FMLs). Four types of FMLs in different sequences and MVF (25% and 50%) were produced with hot press and vacuum. Ballistic tests were carried out with a single stage gas gun system. The absorbed energy was calculated from the energy difference that occurred by taking into account the FMLs entry and exit velocity of the projectile and the projectile mass. Damage types were examined after ballistic testing. It was determined that the stacking sequence and MVF significantly affect the impact resistance of FMLs. It was determined that the metal layer, which first encounters the projectile, compared to the polymer matrix composite, is more effective on the impact resistance of FMLs, and the impact resistance increased with the increase of MVF. In addition, the increase in the number of layers, if the top layers remain the same, adversely affected the impact resistance. It was observed that the first layer that encounters the projectile and the amount of MVF have a significant effect on the ballistic impact strength. As the amount of MVF increases, the ballistic impact resistance increases.

In this study, the effect of alkyl ketene dimer (AKD) on the mechanical and physical properties of natural fiber (NF) and glass fiber (GF) reinforced poly(lactic acid) (PLA) composites were investigated in detail. The hybrid PLA composites were manufactured by extrusion method followed by hot press molding. AKD was used to improve the hydrophobicity of hybrid PLA composites and compatibility of NF and PLA in the polymer matrix. The tensile and flexural tests, thickness swelling, water absorption, and contact angle measurements were accomplished for determining the performance of the hybrid PLA composites. The surface morphology of the hybrid PLA composites was also performed by scanning electron microscopy. The incorporation of AKD and NF into PLA matrix improved the mechanical strengths by 40% and above compared to those of samples without AKD. But, tensile and flexural moduli decreased as 7% and 14% of the samples with NF and AKD, respectively. Contact angle was higher for the hybrid PLA composites with AKD compared with the composites without AKD. However, the results revealed that in the presence of GF, AKD had no significant effect on overall properties of the hybrid PLA composites. In the light of the findings, AKD may have a potential usage as coupling agent in the NF filled PLA composites.

Short wood fibers (SWF) and a water based and formaldehyde free cross linking acrylate resin have been used to produce bulk biocomposites, as a possible material for automotive and friction applications. SWFs of 200–400 µm in length were mixed with the resin in various proportions (40–60 wt%) using a kneading device. The mixture was dried in an oven and later cured in a hot press. Two curing cycles were used for this study: (a) curing at a temperature of 150°C and a pressure of 70 bar and (b) curing at 170°C and a pressure of 80 bar. Various morphological features, flexural and thermal properties, density, and specific wear rate under sliding against smooth steel were examined. Results show that increase in fiber weight fraction led to increase in tensile strength when the material was processed with 170°C and a pressure of 80 bar. Composites with 60 wt% SWF processed with 170°C and a pressure of 80 bar exhibited the highest flexural strength (64 MPa) and flexural modulus (7.2 GPa). Composites processed at lower temperature and pressure (150°C and 70 bar) are found to possess inferior mechanical properties compared with those processed at higher temperature and pressure (170°C and 80 bar). This composite also possessed a nearly stable storage modulus up to 50°C. All composites showed specific wear rate between 10−5 and 10−6 mm3/(Nm) and a very high friction coefficient of μ = 1.25 against smooth steel surfaces. SEM images revealed that there is a very good interfacial adhesion between the fibers and the matrix. POLYM. COMPOS., 2017. © 2017 Society of Plastics Engineers

In the presented study, lithium chloride (LiCl) was used as a modifier to reduce the melting point of polyamide 6 (PA6) and low melting point PA6/wood fiber composites (LPA6/WFC) were prepared with a hot-press machine. Non-isothermal crystallization analysis revealed that as little as 3 wt% LiCl decreased the crystallinity of LPA6/WFC from 21.43% to approximately 10% and reduced the melting point of composites from above 220°C to below 200°C, hence the composites can be produced industrially as well as severe degradation of wood fibers can be avoided. Both LiCl and wood fibers increased the glass transition temperature (Tg) of LPA6/WFC, and the Tg of the composites can reach up to 83.2°C, indicating that composites subjected to high temperature circumstances can still retain good dimensional stability and rigidity. In addition, the composites exhibited good mechanical properties, revealed by a flexural strength of the composites of up to 92 MPa. POLYM. COMPOS., 2017. © 2017 Society of Plastics Engineers

Continuous basalt fiber (BF) reinforced epoxy matrix composites with different contents of micro-tungsten powder were fabricated by hot-press process with prospective of combined radiation shielding and mechanical functions. Gamma photon shielding and mechanical properties of the composites were evaluated. The measured mass attenuation coefficient shows that tungsten filler significantly improves the radiation shielding property of BF composite, especially for low and moderate photon energies of 80 and 356 keV. Flexural strength of BF composite decreases along with increasing tungsten concentration, while flexural modulus and interlaminar shear strength are not obviously affected by tungsten content. Given the advantages of lightweight, high mechanical property and good radiation shielding performance, the studied BF/tungsten composite is promising material with integrated shielding and structural properties for use in nuclear industry. POLYM. COMPOS., 00:000–000, 2017. © 2017 Society of Plastics Engineers

The effect of nanosilica content (0, 0.5, and 2 wt%) on mechanical performance of carbon fabric woven cloth reinforced polymerized poly (butylene terephthalate) resin composites (CF/pCBT) is investigated. The catalyst and nanosilica particles are added on the prepreg surface, and hot-press processing is adopted in order to manufacture CF/pCBT composites. The experimental results reveal that nanosilica could enhance the mechanical performance of CF/pCBT composites. After adding nanosilica in the composites, elastic modulus enhances 23.96%, and Mode-II fracture toughness increases 380.43%. Scanning electron microscope observation shows that dispersity of nanoparticles in composites plays an important role on the overall mechanical performance of the obtained composites. Furthermore, failure mechanism has been analyzed according to the damage morphology. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

The polyimide (PI) fabric/epoxy (EP) composites modified with different content of micro-SiO2 hollow spheres were prepared by dip-coating and subsequently hot-press process. For comparison, the pure EP and the unmodified PI fabric/EP composite were also fabricated. The differential scanning calorimetry was conducted to investigate the crosslinking reaction of composites. The results indicated that there exhibited a remarkable improvement in the mechanical and tribological properties of PI fabric/EP composites after incorporating the micro-SiO2. The best tribological properties were obtained when the content of micro-SiO2 was 2 wt%, whose wear rate was 71.9% lower than that of unmodified PI fabric/EP composite. The worn surfaces were observed by a scanning electron microscope to illustrate the friction mechanisms. Note that the skeleton network structure of fabric throughout the whole composites supported the matrix. At the same time, the microparticulates filled in the interstices of fabrics interwoven structure and the gaps between layers of fabrics, which propped up the skeleton network of fabric under the high frictional load and afford excellent interface between fabrics and EP. This ensures the outstanding tribological properties of PI fabric/EP composites. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

Epoxy resin was modified by adding a silane coupling agent/nano-calcium carbonate master batch. Then, samples of binary carbon fiber/epoxy composites and ternary fiber/nano-CaCO3/epoxy were prepared by hot press process. The interlaminar shear strength (ILSS) of the carbon fiber/epoxy composites was investigated and the results indicate that introduction of the treated nano-CaCO3 enhances ILSS obviously. In particular, the addition of 4 wt% nano-CaCO3 leads to 36.6% increase in the ILSS for the composite. The fracture surfaces of the carbon fiber/epoxy composites and the mechanical properties of epoxy resin cast are examined and both of them are employed to explain the change of ILSS. The results show that the change of ILSS is primarily due to an increase of the epoxy matrix strength and an increase of the fiber/epoxy interface. The bifurcation of propagating cracks, stress transfer, and cavitation are deduced for the reasons of strengthening and toughening effect of nano-CaCO3 particles. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

The thermal behavior of chemically modified jute fiber-reinforced polyethylene (PE) nanocomposites was investigated. Nanocomposites were prepared by hot press molding technique using different fiber loadings (5, 10, 15, and 20 wt%) for both treated and untreated fibers. Jute fibers were chemically modified with benzene diazonium salt to increase their compatibility with the PE matrix. Surface and thermal properties were subsequently characterized. Fourier transform infrared spectroscopy and scanning electron microscopy analysis were used to study the surface morphology. Thermogravimetric analysis (TGA) and differential scanning calorimetry were carried out for thermal characterization. Fourier transform infrared spectroscopy and scanning electron microscopy study showed interfacial interaction among jute fiber, PE, and nanoclay. It was observed that, at optimum fiber content (15 wt%), treated jute fiber-reinforced composites showed better thermal properties compared with that of untreated ones and also that nanoclay-incorporated composites showed enhanced higher thermal properties compared with those without nanoclay. POLYM. COMPOS., 38:1266–1272, 2017. © 2015 Society of Plastics Engineers. © 2015 Society of Plastics Engineers

This work evaluates different chemical treatments on cellulose fibers as reinforcement agents in poly(ethylene-vinyl acetate) (EVA) composites. The cellulose fibers were prepared with three chemical modifications using triethoxyvinylsilane, acetic anhydride (AA), and glycidyl methacrylate (GMA). Composites were prepared with 10 phr of cellulose fibers by means of extrusion and hot press conformation. The fiber treatment levels were successfully demonstrated through Fourier transform infrared spectroscopy with the appearance of characteristic bands in each chemical group, and scanning electron micrographs showed altered textures on the surfaces, polymerized material and fiber agglomerations after the chemical treatments that were most evident in the AA and GMA treatments. The composites reinforced with treated fibers showed improvement in their mechanical properties at the yield points and were reduced in deformation. When activated with dicumyl peroxide, the mechanical properties were even more improved and the interface regions exhibited better interactions between the cellulose fibers and the EVA matrix. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

Fiber hybrid polyimide-based (PI-based) composites reinforced with carbon fiber (CF) and poly-p-phenylene benzobisthiazole (PBO) fiber of different volume fractions were fabricated by means of hot press molding technique, and their mechanical properties and tribological behaviors under sea water lubrication were systematically investigated in relation to the synergism of CF and PBO fiber. Results showed that the incorporation of CF or PBO fiber improved the tensile strength, hardness, and wear resistance of PI. More importantly, because of the synergistic enhancement effect between CF and PBO fiber on PI matrix, the combination of 10%CF and 5%PBO fiber reinforced PI-based composite had the best mechanical and tribological properties, showing promising application in ocean environment. POLYM. COMPOS., 37:1650–1658, 2016. © 2014 Society of Plastics Engineers

The flake graphite, polytetrafluoroethylene, and molybdenum disulfide (MoS 2 ) filled phenolic resin-based composites were prepared by hot press molding. The thermal, mechanical, and tribological properties of composites were studied systematically. The morphologies of the worn surfaces and the change of chemical compositions during the sliding process of the composites were analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. It was found that the heat-resisting performance and the hardness of the composites are less affected by solid lubricants, while the solid lubricants did harm to the flexural strength of the composites. The friction and wear behaviors of composites highly depended on the volume fractions of solid lubricants and the sliding conditions. The wear resistance increases and the coefficient of friction decreases when the filler load increases. In addition, the appropriate content of solid lubricants is beneficial to reducing the sensitivities of the composites to load and sliding speed.

Vapor-grown carbon nanofiber (VGCNF)/water-borne epoxy (WEP) and SiO2/WEP composites were successfully synthesized via freeze drying and hot-press molding. VGCNFs were mixed directly with a WEP emulsion, while SiO2 was synthesized by in situ hydrolysis of TEOS solution (3-triethoxysilylpropylamine (KH550): tetraethoxysilane (TEOS): absolute ethanol = 1:5:20, w/w/w) dispersed in the WEP emulsion. WEP composites were obtained from these mixtures by freeze drying and compressing under a pressure of 10 MPa at 120°C for 2 h. The morphology and mechanical properties of the WEP composites were investigated by transmission electron microscopy, scanning electron microscopy, dynamic mechanical analysis and tensile testing. The shape memory (SM) properties of the WEP composites were evaluated by fold-deploy SM testing. The effects of filler content and recovery temperature on the SM properties were revealed through systematic variation. The results confirmed that VGCNF and in situ hydrolyzed SiO2 were homogenously dispersed and incorporated into the WEP matrices. Thus, significant improvements in the mechanical and SM properties of the composites were achieved. POLYM. COMPOS., 36:1712–1720, 2015. © 2014 Society of Plastics Engineers

Nanocomposites of blends of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) with multiwalled carbon nanotubes (CNTs) were prepared by melt mixing and hot press molding followed by quenching or annealing (120°C, 24 h). PMMA-rich nanocomposites showed higher electrical conductivity than PVDF-rich samples at identical CNT loading. At a specific composition, the quenched nanocomposites showed electrical conductivity values three to four orders of magnitude higher than those observed in annealed samples. Measurement of the dielectric constants also supported the electrical conductivity results. In the annealed samples, agglomerated CNTs located mainly in the PVDF crystalline phase were observed. Addition of CNTs promoted the crystallization, and especially, the formation of β-crystals, which was confirmed by X-ray diffraction. The thermal behavior of nanocomposites from differential scanning calorimetry (DSC) analysis was explained in terms of the three-phase model involving the presence of the rigid amorphous fraction, the mobile amorphous fraction, and the crystalline phase. POLYM. COMPOS., 36:1195–1204, 2015. © 2014 Society of Plastics Engineers

Nanosilica/polyarylene ether nitriles terminated with phthalonitrile (SiO2/PEN-t-Ph) composites were prepared by hot-press approach. To ensure the nano-SiO2 can disperse uniformly, the solution casting method combined with ultrasonic dispersion technology had been taken previously. The mass fraction of nano-SiO2 particles was varied to investigate their effect on the thermal, mechanical, and dielectric properties of the nanocomposites. From scanning electron microscope images, it was found that the nanoSiO2 particles were dispersed uniformly in the PEN-t-Ph matrix when the addition of nano-SiO2 was less than 16.0 wt%. However, when the mass fraction of nano-SiO2 increased to 20.0 wt%, the nano-SiO2 particles tend to self-aggregate and form microns sized particles. Thermal studies revealed that nano-SiO2 particles did not weaken the thermal stabilities of the PEN-t-Ph matrix. Mechanical investigation manifested that the SiO2/PEN-t-Ph nanocomposites with 12.0 wt% nano-SiO2 loading showed the best mechanical performance with tensile strength of 108.2 MPa and tensile modulus of 2107.5 Mpa, increasing by 14% and 19%, respectively as compared with the pure PEN-t-Ph film. Dielectric measurement showed that the dielectric constant increased from 3.70 to 4.15 when the nano-SiO2 particles varied from 0.0 to 20.0 wt% at 1 kHz. Therefore, such composite was a good candidate for high performance materials at elevated temperature environment. POLYM. COMPOS., 35:344–350, 2014. © 2013 Society of Plastics Engineers

[EN] In this work, green composites from renewable resources were manufactured and characterized. A fibrous material derived from Posidonia oceanica wastes with high cellulose content (close to 90 wt% of the total organic component) was used as reinforcing material. The polymeric matrix to bind the fibers was a protein (wheat gluten) type material. Composites were made by hot-press molding by varying the gluten content on composites in the 10¿40 wt% range. Mechanical properties were evaluated by standardized flexural tests. Thermo-mechanical behavior of composites was evaluated with dynamic mechanical analysis (torsion DMA) and determination of heat deflection temperature. Morphology of samples was studied by scanning electronic microscopy and the water uptake in terms of the water submerged time was evaluated to determine the maximum water uptake of the fibers in the composites. Composites with 10¿40 wt% gluten show interesting mechanical performance, similar or even higher to many commodity and technical plastics, such as polypropylene. Water resistance of these composites increases with the amount of gluten. Therefore, the sensitiveness to the water of the composites can be tailored with the amount of gluten in their formulation., The authors would like to acknowledge the Wallenberg and Lars-Erik Thunholms Foundation for the economical support through the concession of a Postdoctoral Fellowship in Forest related. Authors would also like to thank Marcos and Elena for helping in collecting P. oceanica balls.

Core-shell composite nanofibers with PA-6 (Nylon-6) as core and Poly (methyl methacrylate) (PMMA) as shell were fabricated by a coaxial electrospinning method, which were later made into nanofiber reinforced transparent composites through a hot press treatment. Morphological and structural characterizations for the composite nanofibers and the transparent composites were realized in terms of SEM, TEM, and FTIR techniques. The fiber reinforcement feature of the PA-6 was demonstrated by the SEM photos of a composite sample fractured in liquid nitrogen. Through TGA and DSC tests, it was observed that thermal endurance and glass-transition temperature of the nanofiber reinforced composites altered in variation with the contents of the reinforcing PA-6. Experimental results indicated that the mechanical performance of the nanofiber reinforced transparent composites was obviously improved, and its transparency decreased a little with an increase in the PA-6 content. As long as, however, a sacrifice of 10% in transparency was specified, an increment of more than 20% in the mechanical properties of the composites was achievable. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Poly(phthalazinone ether sulfone ketone) (PPESK) is a novel high performance thermoplastic with outstanding high temperature resistance and excellent mechanical properties and therefore, it is a very ideal candidate matrix for advanced composites. However, its high melting viscosity makes the melting process difficult. In this article, two well-known high performance thermoplastics, polyetherimide (PEI) and polyethersulfone (PES) were introduced to PPESK in order to reduce the melting viscosity of PPESK and to improve the properties of composites. The effect of addition of PEI and PES on the resultant composites was studied. A series of unidirectional composites were made of PPESK and its PEI and PES blends as matrix and continuous carbon fiber (T700) as reinforcement. The solution prepregging method and hot-press molding method were used in preparation of composites. The effects of polymer blends matrix on mechanical properties, interfacial adhesion, and fracture mode were studied by three points bending, interlaminar shearing, porosity, and scanning electron microscope test. The results show that the mechanical properties and interfacial adhesion increases, and the porosity decrease after blending PEI or PES in the matrix. Addition of PEI and PES to PPESK results in an obvious transition of fracture mode. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Blends based on various compositions of low-density polyethylene (LDPE) and plasticized starch (PLST) were prepared by melt extrusion and molding in the form of sheets under hot press. The rheology properties during mixing were studied in terms of torque and temperature against mixing time. The structural properties of LDPE/PLST blends before and after electron beam irradiation was characterized by IR spectroscopy, tensile mechanical testing, and scanning electron microscopy (SEM). The torque-time curves during the mixing process showed that the values of torque in the first region of mixing for pure LDPE or LDPE/PLST blends are higher in the presence of the compatibilizer PEMA than that in the presence of EVA. In addition, the stability of mixing was attained after a short time in the presence of PEMA. The IR spectroscopy suggests that the compatibilization by EVA and PEMA compounds proceeds through the formation of hydrogen bonding during mixing and this compatibility was improved after electron beam irradiation. The stress–strain curves of pure LDPE and its blends with PLST showed the behavior of tough polymers with yielding properties. The SEM micrographs of the fracture surfaces give supports to the effect of EVA and PEMA as compatibilizers and the effect of electron beam irradiation. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers

The possibility of producing wood-plastic panels using a melt blend/hot press method was studied in this research. The studied panels were compared with conventional medium density fiberboard (MDF) and particleboard (PB) panels. Wood-plastic panels were made from high density polyethylene (as resin) and MDF waste and PB waste (as natural fiber) at 60, 70, and 80% by weight fiber loadings. Nominal density and dimensions of the panels were 1 g/cm3 and 35 × 35 × 1 cm3, respectively. Mechanical properties of the panels including flexural modulus, flexural strength, screw and nail withdrawal resistances, and impact strength were studied. Results indicated that the mechanical properties of the composites were strongly affected by the proportion of the wood flour and polymer. Maximum values of flexural modulus of wood plastic panels were reached at 70% fiber content. Flexural strength, screw and nail withdrawal resistance, and impact strength of wood plastic composites declined with the increase in fiber content from 60 to 80%. This was attributed to the lack of compatibility between the phases. The produced panels outperformed conventional PB panels regarding their mechanical properties, which were acceptable when compared with MDF panels as well. The best feature in the produced panels was their screw withdrawal resistance, which is extremely important for screw joints in cabinet making. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers

Process simulation is of great importance in the development of processes for cost-effective fabrication of composite structures, particularly for thermoset matrix composites. For the simulation of autoclave or hot press process, it requires knowledge of the compaction behavior and the saturated transverse permeability of fiber reinforcements. In this paper, a simple method without any sophisticated equipment is shown, which can simultaneously measure the compaction curve and the saturated transverse permeability as a function of fiber volume fraction. The method was used to measure the properties of S-2 glass rovings and T700S carbon rovings prepregs. The effects of the impregnating fluid variety, the initial fiber volume fraction of prepreg, and the lay-up type on the compaction behavior were investigated. The transverse permeability was also studied as a function of fiber content for various lay-up types. The results indicate that Gutowski's compaction model and the modified Kozeny-Carman equation proposed by Gutowski, which are important input parameters for the resin flow model, can be used to adequately fit the experimental data. POLYM. COMPOS. 28:61–70, 2007. © 2007 Society of Plastics Engineers

The effects of the fiber compression and the length distribution on the flexural properties of short kenaf fiber-reinforced biodegradable composites were investigated. Two types of kenaf (KU and KT) that were different in the density and the length distribution were used as reinforcements. These fibers were mixed with a corn–starch-based resin, and the composite specimens were fabricated by a hot press forming. The flexural modulus in the KU specimens was not different from that in the KT, despite the difference of the fiber Young's modulus (KU 14.5 GPa and KT 22.1 GPa). This was because the KU was compressed more than the KT in the composite specimen because of the lower density structure. However, in the longest fiber (10.5 mm), the flexural strength in the KT specimens was considerably higher by 67% than that in the KU. The reason was that the KT did not include the fibers below the critical length (4.2 mm) because of the narrower fiber distribution than the KU. In fact, the flexural strength in the KT specimen significantly decreased with decrease in the average fiber length, which included the fibers below the critical length. Moreover, the flexural modulus agreed well with the calculated values by Cox's model that incorporated the effect of the fiber compression. POLYM. COMPOS. 27:170–176, 2006. © 2006 Society of Plastics Engineers

This study examined the differences between formaldehyde-free wood composite panels made with maleated polyethylene (MAPE) and maleated polypropylene (MAPP) binding agents. Specifically, the study investigated the contrasts of (a) base resin type, PE vs. PP, (b) molecular weight/maleic anhydride content in MAPP binding agents, and (c) the manufacturing methods (reactive extrusion vs. hot press) on the physicomechanical properties of the composites. FTIR and XPS analyses of unmodified and modified wood particles after reactive extrusion with maleated polyolefins provided evidence of chemical bonding between the hydroxyl groups of wood particles and maleated polyolefins. Although extruding the particles before panel pressing gave better internal bond (IB) strength, superior bending properties were obtained through compression molding alone. MAPP-based panels outperformed MAPE-based panels in stiffness. Conversely, MAPE increased the IB strength of the panels compared with MAPP. Polymer base resin had no effect on modulus of rupture or screw holding capacity. Differences between the two maleated polypropylene compounds were not significant for any of the mechanical properties tested. Formaldehyde-free wood composites manufactured in this study often outperformed standard requirements for conventional particleboard, regardless of material composition or manufacturing method used. POLYM. COMPOS., 27:599–607, 2006. © 2006 Society of Plastics Engineers

A forecast-based thermal control system was developed to cure thick composite laminates that produced large exothermic reactions. The system used process simulation models for heat transfer and compaction to predict future cure conditions at a designated forecast time so that the system can respond to avoid approaching adverse conditions. The thermal control system derived cure cycles that eliminated exotherms and maintained uniform through-the-thickness temperature gradients for 3-cm-thick AS4/35016 laminates. The on-line results indicated that cure cycles were slightly different from off-line simulation results, mainly because of the slow response of the hot press. Nevertheless the system was able to satisfy the cure criteria under such unforeseen circumstances, which demonstrated the flexibility of the forecasting method.

Long-fiber reinforced thermoplastic composites were made from 9 mm long glass fiber reinforced PP pellets by alternative procedures of roll-mill and hot-press molding. The severe problem of fiber breaking during the process could be avoided by this method. The average fiber length of this composite was ∼7 mm long. More than 80% of fibers in the composite were aligned within the 20° range. In the major fiber-oriented direction, at 25°C, the tensile strength of this composite was 205 MPa. At elevated temperatures in the range of 25°C to 125°C, the tensile strength was inversely proportional to the temperature. The two-parameter Weibull distribution function was used to simulate the strength distribution of the composite. Results showed that the strength distribution curve shifted from high to low as the temperature increased.