Corn oil‐based composites reinforced with continuous glass fibers: Fabrication and properties

Novel thermosetting composites have been successfully developed using glass fibers to reinforce regular corn oil (COR) and conjugated corn oil (CCOR) resins prepared by cationic copolymerization with styrene (ST) and divinylbenzene (DVB). The dependence of morphology and physical properties of the composites on the contents of glass fibers and DVB was determined by scanning electron microscopy, dynamic mechanical analysis, thermogravimetric analysis and tensile testing. The glass fiber loading and polymer matrix composition play an important role in improving the mechanical properties and thermal stability of the resulting composites. As the glass fiber content increases from 0 to 45 wt %, the COR‐based composites show an increase in Young's modulus from 4.1 to 874 MPa and tensile strength from 1.7 to 8.4 MPa. Furthermore, the composites exhibit good damping properties and are suitable for applications where reduction of both unwanted noise and vibration is important. Compared with the composites from COR, the CCOR‐based composites exhibit slightly higher thermal stabilities and mechanical properties, due to higher reactivity of CCOR with comonomers. Increasing the DVB content improves the crosslink density of the polymer matrix, leading to a significant improvement in the thermal stabilities and mechanical properties of the resulting composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3345–3353, 2006     

Fabrication and mechanical properties of glass fiber‐reinforced wood plastic hybrid composites

To fully utilize the resource in the municipal solid waste (MSW) and improve the strength and toughness of wood plastic composites, glass fiber (GF)‐reinforced wood plastic hybrid composites (GWPCs) were prepared through compounding of recycled high‐density polyethylene (HDPE) from MSW, waste wood fibers, and chopped GF. Mechanical tests of GWPCs specimens with varying amounts of GF content were carried out and the impact fractured surface of GWPCs was observed through scanning electron microscope (SEM). The tensile strength of GWPCs and the efficiency coefficient values were predicted by Kelly‐Tyson method. The results indicated that the tensile strength and impact strength of GWPCs could be improved simultaneously by adding type L chopped GF (L‐GF), and would be dropped down when type S chopped GF (S‐GF) was included. The tensile strength of GWPCs was well accordant with the experimental result. The efficiency coefficient values of S‐GF and L‐GF are ?0.19 and 0.63, respectively. Inspection of SEM micrographs indicated that L‐GF had achieved full adhesion with the plastic matrix through addition of maleic anhydride‐g‐polyethylene. The main fracture modes of GWPCs included pullout of GF, broken of matrix, and interfacial debonding. Because of the synergistic effects between hybrid components in GF/wood fiber/HDPE hybrid system, a special 3D network microstructure was formed, which was the main contribution to the significant improvement in the tensile strength and impact strength of L‐GF‐reinforced hybrid composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Dynamic mechanical properties of extruded nylon–wood composites

Dynamic mechanical properties determine the potential end use of a newly developed extruded nylon–wood composite in under‐the‐hood automobile applications. In this article, the dynamic mechanical properties of extruded nylon–wood composites were characterized using a dynamic mechanical thermal analyzer (DMTA) to determine storage modulus, glass transition temperature (T_g), physical aging effects, long‐term performance prediction, and comparisons to similar products. The storage modulus of the nylon–wood composite was found to be more temperature stable than pure nylon 66. The T_g range of the nylon–wood composite was found to be between 23 and 56°C, based on the decrease in storage modulus. A master curve was constructed based on the creep curves at various temperatures from 30 to 80°C. The results show that the relationship between shift factors and temperature follows Arrhenius behavior. Nylon–wood composites have good temperature‐dependent properties. Wood fillers reduced the physical aging effects on nylon in the wood composites. The comparison of the nylon–wood composite with other similar products shows that nylon–wood composites are a promising low cost material for industrial applications. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Experimental investigation on reprocessing of extruded wood flour/HDPE composites

This article presents an experimental study on the change in the properties of wood–plastic composites (WPCs) when reprocessed. The degree of properties degradation upon reprocessing, for recycling purpose, can be considered as a key factor to choose an alternative against discarding into the environment. A material which retains its properties when recycled, or at least exhibits insignificant reduction in its properties, is favorable in environmental point of view. To investigate the reprocessing effect on the WPC properties, in this study, cylindrical profiles of WPC, with 60 wt% of wood content, were produced using a twin screw extruder, at first stage (virgin WPC). These profiles were then chopped into granules and used in the reproduction of the same shaped product (recycled WPC). For the measurement of mechanical properties, tensile and three‐point bending tests were conducted. Differential scanning calorimetry (DSC) test was performed to compare thermal behavior of the neat HDPE, virgin and recycled composites. Scanning electron microscopy (SEM) images were also produced to observe the adhesion quality of the components and changes in wood particles size. Physical properties such as density and water uptake were also measured. A reduction in strength was observed upon recycling which was accompanied with the decrease in density, while an increase in the flexural modulus was noticed. The results also indicate that the recycled samples exhibit a higher water uptake. Analysis of thermal behavior showed a slight increase in the melting temperature of the reprocessed composite and decrease in the degree of crystallinity especially at the first stage of the HDPE process. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Soybean and linseed oil‐based composites reinforced with wood flour and wood fibers

Composites consisting of a conjugated linseed or soybean oil‐based thermoset reinforced with wood flour and wood fibers have been prepared by free radical polymerization. The thermoset resin consists of a copolymer of conjugated linseed oil (CLO) or conjugated soybean oil (CSO), n‐butyl methacrylate (BMA), divinylbenzene (DVB), and maleic anhydride (MA). The composites were cured at 180°C and 600 psi and postcured for 2 h at 200°C under atmospheric pressure. The effect of varying filler load, time of cure, filler particle size, origin of the fillers, and resin composition has been assessed by means of tensile tests, DMA, TGA, Soxhlet extraction followed by ¹H‐NMR spectroscopic analysis of the extracts, and DSC. The best processing conditions have been established for the pine wood flour composites. It has been observed that the addition of MA to the resin composition improves the filler‐resin interaction. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Dynamic mechanical behavior of LLDPE composites reinforced with kevlar fibers/short glass fibers

Kevlar fibers (DuPont) and glass fibers have been used to reinforce linear lowdensity polyethylene (LLDPE) by using an elastic melt extruder and the compression molding technique. The impact behavior of hybrid composites of different compositions is compared and has been explained on the basis of volume fraction of fibers. The addition of glass fibers decreases the Izod impact strength of LLDPE. The Izod impact strength of the composite increses when glass fibers are replaced by Kevlar fibers. Dynamic mechanical α‐relaxation is studied and the effect of variation of fiber composition on the relaxation is reported in the temperature range from −50°C to 150°C at 1 Hz frequency. The α‐relaxation shifts towards the higher temperature side on addition of fibers in LLDPE. The addition of fibers increases the storage modulus, E′, of LLDPE. The hybridization of Kevlar and glass fibers helps in desiging composites with a desirable combination of impact strength and modulus. At the low temperature region, E′ increases significantly with glass fibers as compared to that noted with the addition of Kevlar fibers. The α‐transition temperature of composites increases significantly with Kevlar fibers as compared to that observed with addition of glass fibers.     

Mechanical properties of teak wood flour‐reinforced HDPE composites

Mechanical properties such as tensile and impact strength behavior of teak wood flour (TWF)‐filled high‐density polyethylene (HDPE) composites were evaluated at 0–0.32 volume fraction (Φ_f) of TWF. Tensile modulus and strength initially increased up to Φ_f = 0.09, whereas a decrease is observed with further increase in the Φ_f. Elongation‐at‐break and Izod impact strength decreased significantly with increase in the Φ_f. The crystallinity of HDPE also decreased with increase in the TWF concentration. The initial increase in the tensile modulus and strength was attributed to the mechanical restraint, whereas decrease in the tensile properties at Φ_f > 0.09 was due to the predominant effect of decrease in the crystallinity of HDPE. The mechanical restraint decreased the elongation and Izod impact strength. In the presence of coupling agent, maleic anhydride‐grafted HDPE (HDPE‐g‐MAH), the tensile modulus and strength enhanced significantly because of enhanced interphase adhesion. However, the elongation and Izod impact strength decreased because of enhanced mechanical restraint on account of increased phase interactions. Scanning electron microscopy showed a degree of better dispersion of TWF particles because of enhanced phase adhesion in the presence of HDPE‐g‐MAH. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of saline degradation on the mechanical properties of vinyl ester matrix composites reinforced with glass and natural fibers

One important application of polymeric composites reinforced with natural fibers is in the area of naval engineering design. The objective of this work was to study the influence of saline degradation on the mechanical properties of vinyl ester matrix composites reinforced with glass, sisal, and coconut fibers and natural fibers modified with bitumen. All samples presented mass loss after exposure in a salt spray chamber. All materials, except the composite reinforced with coconut–bitumen, showed a decrease in toughness after a salt spray test. The fracture of the vinyl ester resin with sisal and sisal–bitumen fibers showed a fiber bridging mechanism. These materials showed the highest value of toughness among the materials studied. The presence of fiber pullout was observed in the samples of vinyl ester resin reinforced with glass, coconut, and coconut fibers covered with bitumen. In these samples, poor adhesion between the fiber and matrix was observed. The treatment of fibers with bitumen increased the mass loss and decreased the stability of samples in a saline atmosphere. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Polypropylene matrix composites reinforced with pre-stressed glass fibers

Thermoplastic matrix composites have recently emerged as promising engineering materials because of their desirable properties such as high service temperatures, high impact resistance, and processing advantages. However, residual stresses in composites introduced during fabrication are cited as one of the most significant problems in the processing of composites. In some instances these stresses have been shown to significantly degrade the strength of the material, resulting in matrix cracking, debonding, reduced fracture toughness, and delamination. In this work, studies have been carried out on glass fiber reinforced polypropylene composites formed by compression molding process from co-mingled fabrics. The fibers were pre-stressed during the process to produce high performance composite products with low residual microstresses, which are harmful to the properties of the composite. Mechanical tests showed that pre-stress can increase the tensile, flexural and interlaminar shear properties of the composites, and there exists an optimum pre-stress level to gain best properties for each external loading condition.     

Dynamic mechanical properties of particle‐reinforced EPDM composites

The dynamic mechanical property of particle‐reinforced ethylene–propylene–diene monomer (EPDM) matrix composites has been studied by using a dynamic mechanical thermal analyzer (DMTA). The individual composite has been reinforced with the various reinforcing particles as follows: silicon carbide particles (SiCps) of 60 μm in average diameter with various volume fractions (i.e., 10–40%); copper (Cu) and aluminum (Al) particles with 20 vol %; and SiCps with 6 and 36 μm in different average diameters with 20 vol % over the total composite volume. It is shown from the experimental results that the dynamic elastic modulus values increase and the composites with 40 vol % SiCps exhibit higher tan δ values through the entire rubbery phase after the glass transition region compared with the composites with lower particle volume percentages. This shows that the composites with 20 vol % Cu particles have the higher dynamic elastic modulus but the lower peak tan δ value than the composites with other particles of 20 vol % do. Scanning electron microscopy results show that the effective particle volume in the composite with Cu particles is higher than the other composites, although the same particle volume fraction of 20% has been used. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1595–1601, 2003     

Procedure effect on the physical and mechanical properties of the extruded wood plastic composites

This article investigates the effect of raw material preparation on the mechanical and physical properties in wood‐plastic composite (WPC) production. Four possible procedures in material preparation to obtain a determined level of wood content are: (i) to use and feed raw materials in the same ratio of the desired composition (single stage), (ii) to use the batch of granules of the same composition (two‐stage), (iii) to add wood to the batch of granules having a lower wood content, (iv) to add polymer to the batch of granules having a higher wood content. The main question then is that, while it is economically attractive to use granules of a fixed wood content in all productions, whether there are noticeable differences in final properties of the products. The examined compositions were 50, 60, and 70 wt% of wood content which are considered as highly filled WPCs and mainly used in the WPC markets. Thus, 12 sets of WPC profiles were manufactured and the processing conditions (temperature, pressure, and outlet velocity) recorded. The flexural properties, impact strength, density, and water uptake were measured. Results revealed that in the production of WPCs with 50 and 70 wt% of wood content, using the WPC granules with the same composition yields better physical and mechanical properties. However, for producing WPC with 60 wt% of wood content, using WPC granules with 70 wt% of wood and adding appropriate amount of polymer exhibit better results. POLYM. COMPOS. 34:1349–1356, 2013. © 2013 Society of Plastics Engineers     

Effect of the delignification of wood fibers on the mechanical properties of wood fiber–polypropylene composites

The effect of the delignification of hornbeam fibers on the mechanical properties of wood fiber–polypropylene (PP) composites was studied. Original fibers and delignified fibers at three levels of delignification were mixed with PP at a weight ratio of 40:60 in an internal mixer. Maleic anhydride (0.5 wt %) as the coupling agent and dicumyl peroxide (0.1 wt %) as the initiator were applied. The produced composites were then hot‐pressed, and specimens for physical and mechanical testing were prepared. The results of the properties of the composite materials indicate that delignified fibers showed better performance in the enhancement of tensile strength and tensile modulus, whereas the hardness of the composites was unaffected by delignification. Delignified fibers also exhibited better water absorption resistance. Notched impact strength was higher for delignified fiber composites, but it was reduced at higher delignification levels. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4759–4763, 2006     

Effect of structure on mechanical properties of vinyl ester resins and their glass fiber‐reinforced composites

The article describes the effect of structure of vinyl ester resins (VE) on the mechanical properties of neat sheets as well as glass fabric‐reinforced composites. Different samples of VE were prepared by reacting ester of hexahydrophthalic anhydride (ER) and methacrylic acid (MAA) (1 : 1 molar ratio) followed by reaction of monomethacrylate terminated epoxy resin with glutaric (E) or adipic (F) or sebacic acid (G) (2 : 1 molar ratio). The neat VE were diluted with styrene and sheets were fabricated by using a glass mold. A significant reduction in the mechanical properties was observed by increasing the methylene content of resin backbone (i.e., sample E to G). Glass fabric‐reinforced composites were fabricated by vacuum assisted resin transfer molding (VARTM) technique. Resin content in the laminates was 50 ± 5 wt %. Increase in the number of methylene groups in the vinyl ester resin (i.e., increasing the bridge length) did not show any significant effect on limiting oxygen index (LOI) value (21 ± 1) of the laminates but tensile strength, tensile modulus, flexural strength, and flexural modulus all increased though these values are significantly lower than observed in laminates based on resin B. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of talc/MMA in situ polymerization on mechanical properties of PVC‐matrix composites

In this study, polymethyl methacrylate (PMMA)‐coated talc was produced by the in situ polymerization of methyl methacrylate on the talc surface. The polymerization reaction was performed by both batch and semicontinuous emulsion processes. The polymerization kinetics, particle size and distribution, grafting efficiency, and coated‐talc morphology were systematically investigated. It was found that the talc particles have no effect on the polymerization of PMMA. The PMMA produced was found to cover the talc surface well. However, only a small amount can be grafted onto the talc. The size distribution of talc particles treated by semicontinuous emulsion polymerization is more uniform than by batch polymerization. The treated talc was subsequently used as filler in a poly(vinyl chloride) (PVC) matrix, and mechanical properties of the PMMA‐coated‐talc/PVC composites were studied. Morphological structure of PVC‐matrix composites revealed that the PMMA coating on talc improved the dispersion of talc in the PVC matrix and enhanced the interfacial adhesion between the talc and PVC. The mechanical properties of the composites, especially the impact strength, were found to be improved. There appears to be a critical covering thickness of PMMA on the talc surface for optimum toughening. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2105–2112, 2001     

Effects of some PVC‐grafted maleic anhydrides (PVC‐g‐MAs) on the morphology,and the mechanical and thermal properties of (alfa fiber)‐reinforced PVC composites

This work studied the poly(vinyl chloride) (PVC) chemically modified with maleic anhydride (MA) through reactions in solution, using benzoyl peroxide as an initiator. Quantities of the grafted MA were determined by the titration of carboxylic acid groups derived from the anhydride functions. Estimation of the grafted MA level was also performed by using IR absorbance ratio. Increases in reaction time led to higher levels of grafted MA. The effects of three different PVCs grafted with maleic anhydride (PVC‐g‐MAs) types on the morphological, mechanical, and thermal properties of PVC/alfa (fiber) composites were examined. The interfacial properties between fiber and PVC were improved after the addition of PVC‐g‐MA, as was evident from SEM morphology study. Enhancements of the mechanical properties and thermal stability of the PVC‐g‐MA‐treated composites were strongly dependent on the amount of MA grafts. J. VINYL ADDIT. TECHNOL., 19:225–232, 2013. © 2013 Society of Plastics Engineers     

Investigation of mechanical properties of alumina nanoparticle‐loaded hybrid glass/carbon‐fiber‐reinforced epoxy composites

This research work investigates the tensile strength and elastic modulus of the alumina nanoparticles, glass fiber, and carbon fiber reinforced epoxy composites. The first type composites were made by adding 1–5 wt % (in the interval of 1%) of alumina to the epoxy matrix, whereas the second and third categories of composites were made by adding 1–5 wt % short glass, carbon fibers to the matrix. A fourth type of composite has also been synthesized by incorporating both alumina particles (2 wt %) and fibers to the epoxy. Results showed that the longitudinal modulus has significantly improved because of the filler additions. Both tensile strength and modulus are further better for hybrid composites consisting both alumina particles and glass fibers or carbon fibers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39749.     

Thermal expansion of polyurethane reinforced with continuous glass fibers

This paper is concerned with the study of the thermal expansion properties of polyurethanes which are reinforced with randomly oriented continuous glass fibers. The thermal expansion of reinforced polymers is of prime importance since it has a significiant effect on the overall dimensional stability of molded products. In this work the coefficient of linear thermal expansion (CLTE) is measured for both soft and rigid polyurethane containing various amounts of glass fibers. The experimental results show that: (1) there exists a maximum in the CLTE-temperature curves, the position of which depends on the type of resin and not on the glass content; (2) over the range of 0 to +70°C for rigid polyurethane, and –30 to +70°C for soft polyurethane, the CLTE decreases with temperature. The existence of a maximum in the above findings is confirmed with computations from a theoretical expression which was modified by the introduction of an efficiency factor. In applying this expression, parameters such as the Poison's ratios, elastic moduli, and the CLTe's of the resins had to be evaluated at various temperatures. Based on these results, the CLTE-temperature curves were obtained and found to be in agreement with the experimental observations.     

Effect of wood fibers on the rheological properties of i‐PP/wood fiber composites

The effects of wood fibers on the melt rheological behavior of isotactic poly(propylene) (i‐PP)/wood fiber (WF) composites have been studied at WF concentrations of 0–32.2 vol % at 493 K. Shear stress–shear rate variations obeyed a power law equation, and the composites exhibited shear thinning, which increased with filler content. At a low shear rate, the apparent melt viscosity increased, while melt elasticity, after an initial decrease, also increased with WF concentration. At a higher shear rate, after an initial decrease, the melt viscosity showed an increase, as did melt elasticity, with increase in filler content. A titanate coupling agent, LICA 38, used to modify the wood fiber surface, modified these rheological parameters by functioning as a plasticizer/lubricant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 644–650, 2004     

Experimental investigation on the influence of the composition on the morphology and the mechanical properties of short glass fiber‐reinforced polypropylene nanocomposites

Polypropylene composites containing 0–5 wt% layered silicate and 0–30 wt% short glass fibers are prepared by melt compounding. To investigate the influence of different compositions on the mechanical properties of short glass fiber‐reinforced polypropylene nanocomposites, materials with various filler contents are prepared. At a glass fiber content of 10 wt% Young's modulus of the layered silicate‐containing composites decreases by around 30% compared to conventional glass fiber‐reinforced polypropylene. But at higher glass fiber loadings, an increasing modulus of up to 10% is observed. However, the addition of layered silicate results in large decreases of the tensile and the notched impact strength. A maleic anhydride‐grafted polypropylene enhances Young's modulus and the tensile strength. © 2012 Society of Plastics Engineers