Polyethylene Fiber-reinforced Composites Research Articles

Effect of Air Oxidation Treated Carbon Fiber on Mechanical Properties of Carbon Fiber Reinforced Polyethylene Resin Composite

The composite of carbon fiber reinforced polyethylene resin was prepared by using a twin-screw extruder. The effect of carbon fiber oxidation treating on the mechanical properties of carbon fiber reinforced polyethylene resin composite was researched. The tensile fracture failure mechanism of composite was analyzed for both untreated and air oxidation treated specimen. The experimental results indicate that when carbon fiber content is equal, the tensile strength and the elastic modulus of air oxidation-treated carbon fiber-reinforced polyethylene composite are improved than that of the untreated. When the fraction of adding carbon fiber is 3.99%, compared with the pure polyethylene resin matrix, the tensile strength, elastic modulus is increased by 13.12% and 172.91%, respectively. Compared to the untreated carbon fiber reinforced polyethylene resin composite, the tensile strength and tensile modulus is increased by 4.71% and 13.14%, respectively.

Influence of silaned nano-SiO2 on impact properties of carbon fibre-reinforced polyethylene composites

Silaned nano-silicon dioxide (SiO2) was used to improve the adhesion properties of carbon fibre/polyethylene (CF/PE) composites. The nano-SiO2 were treated by silane under different discharge time. And the changes on the surface properties of the treated and untreated composites were studied by impact, three-point bending tests and scanning electron microscopic analysis. The measurement showed that CF increases fracture toughness with the increase in CF content. Too much high content of CF did not further cause the increase in the toughness of CF/PE composite. The impact strength of silaned specimens is still higher than those of the unsilaned ones. The modified composite with the good matrix/fibre adhesion possessed 20% higher interlaminar shear strengths than the composite having weak interface.

RECYCLE OF PLASTIC WASTE AND AGRICULTURAL WASTE

Manufacturing of polymer composites using plastic waste is one of the solutions to solve the environmental pollution problems caused by non-biodegradable polymer. In this study, Rice husk fiber Reinforced Polyethylene composites (RhRP) have been fabricated with rice husk fiber and plastic waste (recycle low density polyethylene) by compression molding method. Effect of fiber volume fraction, pressure and temperature on the properties of the composite samples was studied. In addition, mechanical properties, thermal properties and durability of RhRP composites were measured. Moreover, chemical modification of rice husk fiber was done through acid and aqueous alkaline solution. The modified fiber samples exhibit the higher strength as well as the lower water absorption rate compared with the unmodified fiber composite samples. Therefore, the resistance to aging of the composites in aqueous environment improved significantly for the modified composite samples. Furthermore, Scanning Electron Microscope (SEM) was also used to characterize the surface feature and the interfacial adhesion between fiber and matrix polymer. The modified composite samples reveal better interfacial adhesion than the unmodified composite ones. Thermo Gravimetric Analysis (TG/DTA) was employed to determine thermal stability of the composite samples. The modified fiber samples have higher thermal stability than the unmodified composite ones.

Shear behavior of soft-matrix composites reinforced with polyethylene loop-formed fibers

A soft material is defined as a substance that its mechanical properties depend on ambient conditions, e.g. external stresses, temperature, etc. Since composite structures with soft-material matrix do not have adequate pullout resistance with flat-type reinforcements such as fibers, there are a large number of cases where reinforcements with passive resistance are used in conjunction with ordinary fibers. Randomly distributed loop-formed fiber (RDLFF) is a novel idea to reinforce these types of composite materials. Therefore, the main aim of this paper is to use polyethylene RDLFF elements in soft-matrix composites. First, shear behavior of polyethylene RDLFF-reinforced composite was modeled with the use of force-equilibrium method, and then it was compared with that of flat-polyethylene fiber. In the next step, a set of laboratory direct shear tests was conducted on different samples including the neat treatment, polyethylene RDLFF and polyethylene fiber-reinforced composites. Thus, it was shown that through the shearing, a loop-formed fiber has two reinforcing effects including the “fiber effect” and the “loop effect”. The “loop effect” is the main advantage of using RDLFF to ordinary fibers at the same orientation and it is also the major difference in using the two kinds of fibers. The proposed model also indicated that the number of looped-form fibers, fiber diameter, coefficient of friction between fiber and matrix, loop dimension, tensile modulus of fiber, shearing zone and vertical compressive stress determine the shear resistance of RDLFF-reinforced composite. Therefore, the proposed model adequately predicts the shear behavior of soft-matrix composites reinforced with fibers and/or loop-formed fibers.

Effects of organic peroxide and polymer chain structure on mechanical and dynamic mechanical properties of sisal fiber reinforced polyethylene composites

AbstractThree types of polyethylene (PE), low‐density PE (LDPE), linear low‐density PE (LLDPE), and high‐density PE (HDPE) were used as polymer matrices to prepare untreated as well as dicumyl peroxide (DCP) treated sisal fiber composites. The effect of polymer chain structure, addition of DCP, and sisal fiber loadings on the mechanical and dynamic mechanical properties of the composite was investigated in this study. It was found that the extent of improvement in tensile properties of the composite samples varied with respect to the polymer molecular characteristics. The elongation at break for all the composites decreased significantly. Young's modulus and the tensile strength of the treated LDPE and LLDPE composites increased significantly compared with the untreated composites, whereas Young's modulus of the treated HDPE samples decreased observably compared with the untreated samples. DCP treatment, however, did not change the tensile strength of HDPE and its composites. The storage modulus results for all the PE composites correlate well with the tensile testing results. In the case of the LDPE and LLDPE samples, the curves of the mechanical loss factor (tan δ) show a clear relaxation around −18°C, which shifted to higher temperature in the treated composites, whereas for HDPE this transition was not seen. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Effects of organic peroxide and polymer chain structure on morphology and thermal properties of sisal fibre reinforced polyethylene composites

The effect of polymer chain structure, addition of dicumyl peroxide (DCP) to initiate grafting onto the fibre, and different fibre loadings on the morphology and thermal properties of polyethylene/sisal fibre composites was investigated. The gel content results suggest both crosslinking between the polyethylene chains and grafting onto the sisal fibres. There were significant differences in gel contents between the composites because of the differences in the polyethylene molecular structures. The SEM micrographs of the samples show clear evidence of grafting, particularly in the case of the LDPE and LLDPE composites. The presence of the sisal fibres gave rise to thermally less stable composites compared to the neat matrices, whereas marginal differences in stability were observed between the untreated and peroxide treated composites. The DSC results show interesting trends in terms of the influence of fibre content and dicumyl peroxide treatment on the crystallisation behaviour of the composites.

Directly fabricated inlay-retained glass- and polyethylene fiber-reinforced composite fixed dental prostheses in posterior single missing teeth: a short-term clinical observation.

To evaluate the clinical usefulness of directly fabricated glass and polyethylene resin-bonded fiberreinforced composite (FRC) inlay-retained fixed dental prostheses (FDPs) in posterior single missing teeth over a short period of time. Fourteen inlay-retained FRC FDPs with tub-shaped or box-shaped retainers were directly constructed in patients of both genders. A baseline examination was performed and the patients were examined regularly at 6-month intervals. The sulcus bleeding index, Silness-Löe plaque index, and probing depths of the abutments were checked regularly. Modified US Public Health Service (USPHS) parameters were used to compare the restorations at baseline and final examination. The Kaplan-Meier survival estimation method was performed to detect the overall survival rates and mean survival times of the restorations at the end of the follow-up. The length of the clinical observation was between 16 and 40 months for the FDPs still functioning after the end of the follow-up. No partial or total debonding of the prostheses or fracture of the frameworks was detected. Four veneering composite fractures at the veneer layer/fiber framework interface occurred in the pontic elements of 2 glass FRC FDPs and 2 polyethylene FRC FDPs after 6 and 10 months, and 20 and 22 months, respectively. Periodontal evaluation revealed clinically acceptable results, as did the USPHS evaluation. The overall survival curves of Kaplan-Meier at the end of the follow-up illustrated a 71% survival rate for the both glass and polyethylene FRC FDPs with mean survival times of 27 and 35 months, respectively. This study reported a mean period of service of 19 and 31 months for directly fabricated inlayretained glass and polyethylene FRC FDPs, respectively, with a 71% survival rate for the two framework constructions. Within the limitations of the study, these results can only be considered as preliminary. However, because of the lack of clinical data available for directly fabricated inlay-retained FRC FDPs, the results of this clinical observation may contribute to the still-evolving clinical knowledge of the FRC restorations.

X-Ray Stress Measurement of Fiber Reinforced Plastics Composite Material

X-ray stress measurement with sin2ψ method is one of useful tools to detect residual stresses in manufactured products. In this study, the residual stresses in the tungsten fiber reinforced polyethylene composite were examined by X-ray stress measurement technique. The transmission diffraction method was employed in residual stress measurement of polyethylene matrix. The X-ray elastic constant of high density polyethylene (HDPE) which formed matrix of the composite was estimated before residual stress measurement. The results of sin2ψ diagram with transmission method show good linearity under the several tensile loading. After that the residual stresses in the composite were investigated for HDPE matrix phase. From the measurement results, the tensile residual stresses existed in fiber longitudinal direction and compressive ones in transverse direction for HDPE matrix.

Coconut fibre reinforced polyethylene composites: effect of natural waxy surface layer of the fibre on fibre/matrix interfacial bonding and strength of composites

Coconut fibre has been used as reinforcement in low-density polyethylene. The effect of natural waxy surface layer of the fibre on fibre/matrix interfacial bonding and composite properties has been studied by single fibre pullout test and evaluating the tensile properties of oriented discontinuous fibre composites. The waxy layer provided good fibre–matrix bond such that removal of the layer resulted in drastic decrease of the fibre pullout stress, increase of the critical fibre length and corresponding decrease in tensile strength and modulus of the composites. The waxy layer of polymeric nature also exhibited a stronger effect on interfacial bonding than by grafted layer of a C 15 long-chain alkyl molecule onto the wax-free fibre. The morphological features of the fibre along with its surface compatibility with the matrix favours oriented flow of relatively long fibres along with the molten matrix during extrusion.

Effect of Strain Rate and Temperature on the Tensile Failure of Pineapple Fiber Reinforced Polyethylene Composites

The dependence of temperature and strain rate on the mechanical properties of pineapple leaf fiber (PALF) reinforced polyethylene (LDPE) composites has been investigated. The effects of fiber loading, fiber orientation, and fiber treatment on the test properties were studied. The tensile strength of the composite was found to be decreased and elongation increased up to 40'C, decreasing thereafter as the temperature was increased from 40 to 80'C. Failure at low temperature and or high strain rate occurred due to brittle matrix fracture, which was evident from SEM micrographs. Activation energy of the failure was calculated using an Arrhenius equation. Failure envelope is generated in order to understand the effect of temperature and strain rate on composite properties. Composites with longitudinally oriented fibers showed higher retention of tensile properties at elevated temperatures. Fibers treated with poly(methylene) poly(phenyl) isocyanate (PMPPIC) showed maximum retention in strength at higher temperature.

Stress Relaxation Behavior of Short Pineapple Fiber Reinforced Polyethylene Composites

Stress relaxation behavior of short pineapple fiber reinforced polyethylene composites in tension has been studied with special reference to the effect of fiber loading, fiber length, chemical treatment and fiber orientation. Chemical treatments of fiber with reagents such as isocyanate, silane, alkali and peroxide were carried out to improve the interface adhesion between fiber and matrix. The effects of strain level, chemical treatments, pre-straining, and aging on the rate of relaxation have been investigated. It was found that the stress relaxation rate decreases with strain level. It was found that incorporation of fiber results in two relaxation processes. The rate of relaxation is decreased with fiber content. It is observed that chemical treatment has significant influence on the relaxation behavior. Composites containing fibers oriented longitudinally have higher relaxation rate than transversely oriented composites. Aging of samples improved the relaxation modulus due to improved interfacial adhesion at higher temperature. It has been demonstrated that the stress relaxation modulus values measured at different strains can be superimposed by a shift along the logarithmic time axis to yield master curves of modulus over an extended time period.

Aqueous powder slurry manufacture of continuous fiber reinforced polyethylene composite

AbstractA model and experiment of an aqueous slurry process are reported. According to an ideal structure of a fiber‐reinforced composite, we present a square geometrical model to build up the relationships among some important parameters in the process such as power particle diameter, wet slurry concentration, flow distance of melting power particle, and fiber volume fraction of the composite. Practical experiments based on these relationships provide the optimum parameters for manufacturing the continuous fiber reinforced polyethylene matrix composite.

Influence of Short Glass Fiber Addition on the Mechanical Properties of Sisal Reinforced Low Density Polyethylene Composites

This paper presents the evaluation of enhancement in the mechanical properties of short sisal fiber reinforced polyethylene composites by the incorporation of short glass fiber as an intimate mix with sisal. Intimately mixed short glass-sisal hybrid fiber reinforced polyethylene composites (GSRP) were prepared by solution mixing technique. The effects of fiber orientation and alkali treatment on sisal fiber in GSRP were studied. Addition of relatively small volume fraction of glass (0.03) to the sisal reinforced polyethylene matrix (SRP) enhances the tensile strength of longitudinally oriented composites by about 80%. Addition of the same volume fraction of glass to the alkali treated sisal incorporated SRP enhances the tensile strength by more than 90%. The flexural strength of the longitudinally oriented composites was also studied. The incorporation of glass fiber ( V f = 0.03) to SRP enhances the flexural strength by more than 60%. The effect of hybridization on water absorption tendency of the sisal fiber was studied by immersing SRP and GSRP in boiling water for 3 hours. It was observed that water uptake of GSRP was 2 to 4 times less than that of SRP composites. Halpin-Tsai equation for composites was tried for calculating the tensile modulus of longitudinally oriented GSRP.

Improved interactions in chemically modified pineapple leaf fiber reinforced polyethylene composites

Mechanical properties of pineapple leaf fiber reinforced low density polyethylene composites have been studied with special reference to the effects of interface modifications. Various chemical treatments using reagents such as NaOH, PMPPIC, silane and peroxide were carried out to improve the interfacial bonding. Both infrared spectroscopy and SEM were used to characterize the interface and the modified fiber surface. It has been found that the treatments improved the mechanical properties significantly. However, the effect varied according to the nature of the treatments. SEM studies on the fracture surfaces revealed the extent of fiber-matrix adhesion. It has been observed that the PMPPIC treatment reduced the hydrophilicity of the fiber and thereby enhanced the mechanical properties of the composites. The addition of a small quantity of peroxide and silane increased the mechanical properties considerably. The action of peroxide is associated with the peroxide-induced grafting of polyethylene on the fiber surface. Among the various treatments, PMPPIC treatment of fiber exhibits maximum interfacial interactions. Attempts have been made to illustrate the interfacial bonding with the help of schematic models.

Failure of Spectra® Polyethylene Fiber-Reinforced Composites under Ballistic Impact Loading

Failure modes of Spectra polyethylene fiber-reinforced composites were examined under ballistic impact loading. Both woven fabric-reinforced laminates and angle-plied unidirectional fiber-reinforced laminates were found to exhibit sequential delamination, cut-out of a plug induced by through-the-thickness shear, and combined modes of shear and tensile failure offibers as obserxed in the cases of glass and graphite fiber composites. At low areal density, both laminates demonstrated similar ballistic limits. However, as areal density increased, differences in ballistic limit became more apparent, with angle-plied composite laminates showing higher values. When subjected to the repeated impact of a constant striking velocity below the ballistic limit, a progressive growth of local delamination was observed until gross failure of composites occurred. The use of lower striking velocity of the projectile led to the increase in cumulative numbers of impacts for full penetration defining an impact fatigue lifetime profile. The results of impact testing indicated that Spectra fiber-reinforced composites with vinyl ester resin matrix have a higher ballistic limit and longer impact fatigue life at a given striking velocity than the polyurethane matrix composites. Less effective absorption of impact energy by flexible polyurethane matrix composites was attributed to much more restrained pattern of delamination growth. Correlated with the results of dynamic mechanical analysis, these trends indicated that the stiffness of resin matrices plays an important role in controlling the ballistic impact resistance of Spectra fiber composites. Damping factor and resultant stress wave attenuation characteristics of materials seem to be less important parameters.

Application of the J‐integral concept for the description of toughness properties of fiber reinforced polyethylene composites

AbstractFor the determination of toughness properties of HDPE/glass fiber and HDPE/cotton fiber composites, an instrumented Charpy impact test has been used. The interpretation of impact load‐deflection curves has been carried out with several concepts of fracture mechanics. Here the limits of linear elastic fracture mechanic (LEFM) have been shown. The change of toughness properties with increasing fiber volume can be described for short fiber reinforced composites with the help of the J‐integral concept in a suitable mode. An application of the conventional Charpy impact test will result in an overestimation of material behavior because of the energy of crack propagation. With the help of a micromechanical model to describe failure processes, taking account of energy dissipative processes, it is possible to calculate fracture mechanical material parameters. Because of the peculiarities of deformation and fracture behavior, the application of elastic‐plastic fracture mechanic (EPFM)‐concepts for fiber reinforced polymers is required.

Surface induced crystallization in ultrahigh-modulus polyethylene fiber-reinforced polyethylene composites

Surface induced crystallization in ultrahigh-modulus polyethylene fiber-reinforced polyethylene composites