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The undesired residual stresses in fiber reinforced polymer composites are developed during their manufacturing processes due to the thermal and chemical shrinkage of the polymer matrix, which negatively affect the performance of the composites. Applying tensile stress to the reinforcement fibers during the curing of the matrix can reduce or eliminate the undesired residual stresses. Furthermore, the undesired tensile residual stress within the matrix can be replaced with beneficial compressive residual stress which can improve the mechanical properties of the composites. In this study, theoretical stress analysis was performed in order to determine the value of the optimum compressive residual stress that is associated with the highest tensile strength. This value was determined based on the tensile testing result of prestressed composites with a 40% fiber volume fraction. For the composites with different fiber volume fractions, a new approach was introduced to estimate the optimum fiber prestressing level which generates the optimum compressive residual stress within the matrix and consequently, the highest tensile strength can be achieved. In order to validate this approach experimentally, prestressed composites with 25 and 30% fiber volume fraction were prepared by applying the estimated optimum fiber prestressing levels during curing of matrix and tensile testing was performed. The result of the stress analysis showed that the value of the optimum compressive residual stress corresponding to the highest tensile strength is 2.5 MPa approximately. The tensile testing results confirmed the validity of the new approach in estimating the optimum fiber prestressing level for the composites with different fiber volume fractions. For both prestressed composites with 25 and 30% fiber volume fraction, the highest tensile strength was achieved when the theoretically estimated optimum fiber prestressing level was applied to the fibers during the curing of the matrix. [ABSTRACT FROM AUTHOR]

The mechanical properties of fiber-reinforced polymer composites depend on several aspects such as the characteristics of constituents, fiber volume fraction, and manufacturing techniques. Fiber prestressing is considered a very attractive manufacturing technique that can be used to produce fiber-reinforced polymer composites with high mechanical properties. This technique has the potential to eliminate or reduce some manufacturing problems like fiber waviness. In the present study, a new approach was used to prepare prestressed fiber-reinforced polymer composites. Unidirectional E-glass fiber-stitched mats were impregnated with epoxy matrix through vacuum-assisted resin transfer molding process. Once the infusion was done, a pre-calculated tensile force was applied to the fiber mats through a hydraulic tensile machine. The impregnated fiber mats were left under tension and vacuum during curing of the epoxy matrix (24 h). Five prestressed samples were prepared by using five different prestressing levels 20, 40, 60, 80, and 100 MPa. In addition, non-prestressed (control) sample was prepared for the purpose of comparison. The influence of fiber prestressing on fiber waviness, fiber volume fraction, and void content was investigated. Flexural, tensile, and compression tests were performed to observe the effect of fiber prestressing on the mechanical properties. The results have shown the success of this new approach in producing prestressed fiber-reinforced polymer composites with high mechanical properties comparing to non-prestressed composites. The microstructure analysis has shown dramatical reduction in fiber waviness for the prestressed samples over control sample. All prestressed samples have shown higher fiber volume fraction and lower void content comparing to the control sample. Also the results have shown as the prestressing level increases, fiber volume fraction increase and void content decreases. Prestressing levels of 40 and 60 MPa were found to be the best candidates, they have led to an increase in tensile strength, compressive strength, and flexural strength by 24.2%, 72.5%, 28% and 28.6%, 100.4%, 26.1%, respectively, comparing to the non-prestressed sample. Ease of implementation and promising results of this new approach would attract the attention toward it. Automotive industry is one potential nominee to apply this approach during manufacturing of fiber-reinforced polymer leaf spring. [ABSTRACT FROM AUTHOR]

Currently, there is a tendency to develop materials that have an increasingly specific purpose for a particular application and the composites can be part of these types of materials. In addition, there is a search for replacement of synthetic fibers with natural ones, because of concerns about the environment. Hybridization of glass fiber composites with sisal fibers can result in improved performance by combining the benefits of each fiber with various applications. Many studies are developed on these types of composites, sisal/glass hybrids, varying certain parameters, such as matrix, orientation of fibers, treatment of fibers, stacking of layers, composition of elements, method of manufacture, among others, characterizing the various types of properties. The present work organizes the researches on the hybrid composites of sisal/glass, in chronological order, highlighting the specifications and parameters used and the main results obtained. [ABSTRACT FROM AUTHOR]

This research was undertaken to investigate the influence of the sizing components, principally coupling agents and film formers, of glass fiber on the interface of reinforced polyurethane composites. The contents of film-forming agents and coupling agents were, respectively, checked by acetone extraction and heat treatment. The categories and chemical structures of the film-forming agents, which mainly exist in the extracting solutions, were investigated by nuclear magnetic resonance spectroscopy. The coupling agents, which mainly existed on the extracted glass fiber surfaces, were analyzed by X-ray photoelectron spectroscopy. Then, the interfacial adhesion properties between glass fibers of untreated, extracted and heat-treated and polyurethane resin were measured with micro-droplet test. The results show that the interfacial shear strength of the glass fiber-reinforced polyurethane composite mainly depends on the coupling agents, in which the N-containing groups play a dominant role. The film formers also take some effects, in which the hydroxyl groups have the greatest contribution. [ABSTRACT FROM AUTHOR]

For both environmental and economic consideration, the use of recycled glass fiber-reinforced flame retardant poly(butylene terephthalate) (RGFFRPBT) is of significant importance. In the study, the mechanical, thermal, rheological, and flame retardant properties of RGFFRPBT granulated by different extruders were evaluated. To explore the relationship between the screw structure and the properties of the extruded RGFFRPBT, the carboxyl content (CC), and intrinsic viscosity ([η]) of the processed polymer and the average GF length (L¯) were investigated. Increasing the shear force of the extruder caused both [η] and L¯ to decrease, whereas the CC increase. Variations of these parameters had a different effect on the properties of the RGFFRPBT. Both of mechanical and thermal properties of extruded RGFFRPBT deteriorated with the increase of screw shear force, while the thermal flowability improved. Furthermore, all the extruded products were classified as V-0 with LOI of 32.2%, and passed the glow wire ignition temperature test (GWIT). The results confirmed that the degradation of properties of RGFFRPBT can be controlled by screw-type extrusion. RGFFRPBT granulated by a single screw extruder with 30 mm diameter and length to diameter ratio of 30 was found to produce material with properties meeting the requirements for electronic and electrical applications. [ABSTRACT FROM AUTHOR]

This paper deals with durability of glass fiber-reinforced polymer composites under sustained loads and simultaneously exposed to either saltwater or tap water. The tensile properties of the specimens before and after conditioning were evaluated along with their moisture uptaking behavior to reveal the durability of the specimens under combined effects. The mass change curves under saltwater and tap water immersion exhibited dual-stage diffusion process. The first stage followed Fickian profile, while mass loss occurred in the second stage with increasing immersion time, attributed to hydrolysis of resin. The weight gain in saltwater was greater than that in tap water. Moreover, the mass change curves under varying percentage of sustained loadings exhibited similar trends, while the maximum moisture uptake was obviously affected by the loading conditions. Based on Fick’s second law, the diffusion coefficients in the first stage under different conditions were determined through the least-square regression technique. It was observed that the tensile strength and modulus were increasing initially upon immersion, which was attributed to curing beyond the initial cure during manufacture. Then, the tensile properties decreased with continued immersion in saltwater or tap water. After 180 days of immersion, the tensile properties degraded at a smaller rate, both for specimens with and without sustained loading. For the saltwater immersion of 360 days, the tensile properties decreased significantly as the sustained loading increased. However, the tap water immersion had less detrimental effect on tensile properties of glass fiber-reinforced polymer. Furthermore, based on Arrhenius concept coupled with fracture mechanics principle, a new model was proposed to describe the combined effects of immersion and sustained load. [ABSTRACT FROM AUTHOR]

Glass fibers reinforced polymer composites have been prepared by various manufacturing technology and are widely used for various applications. Initially, ancient Egyptians made containers by glass fibers drawn from heat softened glass. Continues glass fibers were first manufactured in the 1930s for high-temperature electrical application. Nowadays, it has been used in electronics, aviation and automobile application etc. Glass fibers are having excellent properties like high strength, flexibility, stiffness and resistance to chemical harm. It may be in the form of roving’s, chopped strand, yarns, fabrics and mats. Each type of glass fibers have unique properties and are used for various applications in the form of polymer composites. The mechanical, tribological, thermal, water absorption and vibrational properties of various glass fiber reinforced polymer composites were reported. [ABSTRACT FROM AUTHOR]

Epoxy laminates were prepared by using hybridization of glass fibers and multiwalled carbon nanotubes. Mechanical behaviors of the epoxy hybrid composites were characterized by using flexural, impact, and fracture toughness tests. Morphological properties of the epoxy hybrid composites were investigated by using field emission scanning electron microscopy. Water absorption tests were performed at three different immersion temperatures, i.e. 30, 60, and 90℃. The flexural properties, impact strength and fracture toughness of the epoxy/glass fiber composites increased significantly by the incorporation of multiwalled carbon nanotubes. The kinetics of water absorption for the epoxy hybrid composites conformed to Fickian law behavior. Adding multiwalled carbon nanotubes increases the equilibrium moisture content (Mm) and diffusion coefficient (D), but lowers the activation energy of water diffusion (Ea) for epoxy/glass fiber composites. [ABSTRACT FROM AUTHOR]

Glass fiber epoxy composites are widely used in industries. Liquid epoxidized natural rubber was added to epoxy as the matrix for a fiber-reinforced composite in order to improve its mechanical properties whilst E-glass fiber was used as the composite reinforcement. Flexural test, Izod impact test, tensile test, thermogravimetric analysis, and scanning electron microscopy were performed to investigate the effect of liquid epoxidized natural rubber addition and glass fiber loadings on the mechanical properties of the composite. It was observed that the flexural strength and flexural modulus of the samples increased with increasing glass fiber percentage with 9% as the maximum weight percentage recorded. The tensile strength and Young’s modulus increased with increasing glass fiber content until it reached the maximum value at 9 wt% of glass fiber. The same trend was observed with the impact value of the samples. All the tests were conducted for the composite with and without liquid epoxidized natural rubber addition. The presence of liquid epoxidized natural rubber improved the mechanical properties of the composites due to the plasticizing effect of the rubber particles in the matrix. Thermogravimetric analysis revealed the thermal stability of the composites whilst the scanning electron microscopy shows a heterogeneous dispersed phase of morphology. There was poor adhesion between the matrix polymer and glass fibers due to the use of untreated glass fibers. [ABSTRACT FROM PUBLISHER]

The tribological behaviors of polyetheretherketone reinforced by short glass fibers have been investigated using the ball-on-disc configuration at different applied loads under dry sliding and water lubrication. The effects of water and GF on the wear properties of the hybrid composite have been discussed. It was found that the glass fiber/polyetheretherketone composite showed excellent tribological performance in water lubrication. High wear resistance and low friction coefficient were achieved under a wide range of applied load. The glass fibers bore the main load between the contact surfaces and protected the matrix from further severe abrasion of the counterpart. At the same time, the cooling and boundary lubricating effects of water hindered the melting of glass fiber/polyetheretherketone surface layer which caused a great improvement in the trobological characteristic. Moreover, the transfer between the counterpart materials and the worn surface of the glass fiber/polyetheretherketone was inhibited accounting for the lower specific wear rate under water lubrication. The glass fiber/polyetheretherketone composite was characterized by mild scuffing and fiber protruding under water lubrication, while the plastic deformation and adhesion were significantly abated compared with those under dry sliding. [ABSTRACT FROM AUTHOR]

The synergetic effect of multi-walled carbon nanotubes (MWCNTs), carbon fiber (CF), and glass fiber (GF) on the static and dynamic mechanical and thermal properties of MWCNTs/epoxy (EP), carbon fiber reinforced polymer (CFRP), and glass fiber reinforced polymer (GFRP)/EP composites were studied. Impact, tensile, and flexural strengths and fatigue cycles of MWCNTs/EP, MWCNTs/CFRP/EP, MWCNTs/GFRP/EP were increased with an increase of MWCNTs content in the epoxy resins. The impact strength of MWCNTs/EP composite is increased dramatically from 4.8 J/M (neat resin) to 12.2 J/M (increased 154.1%) by adding 2.0 phr MWCNTs in the composites. The tensile strength of MWCNTs/CFRP/EP was enhanced from 580.1 MPa (CFRP/EP) to 781.4 MPa (increased 34.7%) by adding 0.5 phr MWCNTs. In addition, the flexural strength of MWCNTs/GFRP/EP was increased from 244.1 MPa (GFRP/EP) to 298.1 MPa (increased 22.16%) by adding 0.75 phr MWCNTs. The fatigue cycles of MWCNTs/GFRP/EP were increased from 959 cycles (GFRP/EP) to 3232 cycles (increased 237%) by adding 2.0 phr MWCNTs. The coefficient of thermal expansion (CTE) of MWCNTs/CFRP/EP was decreased significantly by adding 2.0 phr MWCNTs. The CTE of GFRP/EP had a value of 65.5 ppm/°C by adding 2.0 phr MWCNTs and was lower than that of CFRP/EP. [ABSTRACT FROM AUTHOR]

Hybrid composites of polycarbonate (PC) reinforced with short glass fibers (GF) and short carbon fibers (CF) were prepared by twin-screw extrusion and injection molding techniques. Composites were produced in different ratios of GF and CF by maintaining the total fiber loading at 40 wt%. The mechanical properties such as tensile, flexural strength, and impact of these composites were investigated. It was noted that an increase in GF content led to a higher strength of the hybrid composites as compared to CF. Morphological analysis by using scanning electron microscope reveals that CF had poor fiber-matrix interactions with PC, which brought about the decrement of stress-transfer efficiency. A poor fiber-matrix interaction is believed to be the main cause of the lower strength enhancement by CF than expected. Heat deflection temperatures of composites increased with the increment of GF content. From dynamic mechanical thermal analysis, high-storage modulus is observed at the temperature below Tg. Meanwhile, it was observed that surface and volume electrical resistivity decreased by increasing the CF content owing to its conductivity. [ABSTRACT FROM AUTHOR]

The design, fabrication, and testing of an epoxy-glass reinforced polymer composite pressure vessel suitable for high-pressure gas storage have been reported. In this study composite pressure vessels are made up of aluminum alloy 6063 seamless liner and glass/epoxy composite reinforcement. The aluminum liner, which is developed by extruded aluminum tube of internal diameter 141mm and wall thickness 4 mm, is subjected to super plastic deformation. Continuous glass fibers impregnated in epoxy resin are wound on the seamless liner by filament winding process. In this work, 10 pressure vessels were manufactured for 3.5MPa service pressure with marginal safety of 3. Four pressure vessels were subjected to cyclic and burst test; the burst pressures were 10.9, 11.0, 11.0, and 13.0 MPa. [ABSTRACT FROM AUTHOR]

The chemical resistance of the glass/bamboo fibers reinforced polyester composites to acetic acid, sodium hydroxide, ammonium hydroxide, sodium carbonates, benzene, toluene, carbon tetrachloride, and water was studied. The hybrid fiber composites showed better resistance to these chemicals. Besides this, the tensile properties of glass/bamboo fibers reinforced polyester hybrid composites were studied. The effect of alkali treatment of the bamboo fibers on these properties was also studied. It was observed that tensile properties of the hybrid composites increased with glass fiber content. These properties were found to be higher when alkali treated bamboo fibers were used in the hybrid composites. The elimination of amorphous hemi-cellulose with alkali treatment leading to higher crystallinity of the bamboo fibers may be responsible for these observations. [ABSTRACT FROM AUTHOR]

The mechanical and water absorption behavior of the bamboo--glass mat (strand and woven) reinforced epoxy and polyester laminate composites are studied. The hybridization with glass mat increases the mechanical and water resistant properties of the hybrid composites. The increase in properties is higher in the woven glass mat reinforced hybrid composites compared to the strand mat. For both the epoxy and polyester matrix composites, when two layers of strand glass mat were used the mechanical properties increase, but with three layers it shows a decrease in value. Whereas, with woven glass mat reinforcement the mechanical properties increase as the number of glass mat layer is increased. Addition of glass fiber results in reduction of water absorption by the epoxy and polyester bamboo composites. Water absorption is reduced with increase in the glass fibers in the composite. [ABSTRACT FROM AUTHOR]

Glass fiber (GF)-reinforced biodegradable poly(propylene carbonate) (PPC) composites were prepared by melt blending. The effects of reinforcement on the mechanical, thermal, and morphological properties of the PPC/GF composites were investigated. The mechanical properties of the composites were found to be improved obviously by the incorporation of GF. Experimental results of the thermal properties indicated that the GF addition led to the improvement on the thermal stability of the composites, and that the Vicat softening temperature (VST) of the composites was much higher than that of pure PPC resin. Scanning electron microscopic examination revealed a uniform dispersion of GF within PPC matrix at low GF loading level. It was observed that the GF appeared to be oriented within the PPC matrix to some extent, and there was good interfacial adhesion between GF and PPC matrix. [ABSTRACT FROM AUTHOR]

The flexural, compressive properties of bamboo/glass fiber-reinforced epoxy hybrid composites were studied. The effect of alkali treatment of the bamboo fibers on these properties was also studied. It was observed that both flexural and compressive properties of the hybrid composite increase with glass fiber content. These properties were found to be higher when alkali-treated bamboo fibers were used in the hybrid composites. The elimination of amorphous hemi-cellulose with alkali treatment leading to higher crystallinity of the bamboo fibers with alkali treatment may be responsible for these observations. [ABSTRACT FROM AUTHOR]

The present experimental work is aimed at studying the performance of recycled newspaper and recycled newspaper/glass fiber hybrid polypropylene composites. The effects of glass fiber loading and maleic anhydride (MA) as a coupling agent on the tensile behavior and impact strength of composites containing 30wt% fiber were examined. The results suggest that the tensile strengths of the recycled newspaper/PP composites increase with increasing glass fiber content. A value of 55MPa for tensile strength and 4.1 GPa for the tensile modulus is achieved from a hybrid composite containing 10wt% of newspaper and 20wt% of glass fiber. The impact strength of the newspaper/PP composites progressively decreased with increasing glass fiber content. Adding (MA) by 2wt% in the composite formulation significantly improved both the dimensional stability and mechanical properties. Microstructure analysis of the fractured surfaces of modified composites confirmed improved interfacial bonding. Dimensional stability and strength properties of the composites can be improved by increasing the glass fiber content and or by addition of coupling agent. This project has shown that the composites treated with glass fiber and coupling agents will be desirable as building materials due to their improved stability and strength properties. [ABSTRACT FROM AUTHOR]

The effects of weight fraction and length of short bamboo and glass fibers on flexural strength and inter-laminar shear strength (ILSS) of vinyl ester resin and unsaturated polyester (USP) resins were investigated. The bamboo fibers were isolated from the bamboo plant by treating them with dilute solution of sodium hydroxide (0.1 and 1N NaOH) for 72 h and then boiling them in a pressure cooker for 30 min. The fibers were separated, dried, and cut into 5 or 10mm lengths. Composites were fabricated using vinyl ester resin or USP resin as binders. The flexural properties of glass/bamboo fiber reinforced vinyl ester resins were higher than those based on USP resins. This may be due to better wetting of the fibers by VE resins due to their low viscosity and possibility of hydrogen bond formation with hydroxyl group on bamboo fibers. Hybrid composites were fabricated using 50wt% of fibers. The wt% of bamboo fibers in these hybrid composites was varied as 25, 50, and 75wt% of chopped glass fibers (5 mm). Replacement of 25wt% of glass fibers did not affect the flexural modulus and a marginal increase in ILSS was observed. However, replacement of 75% glass fibers by bamboo fibers resulted in a significant decrease in flexural strength, modulus and ILSS. [ABSTRACT FROM AUTHOR]

This article reports the mechanical characterization and sliding wear behavior of glass fiber-reinforced vinyl ester resins of varying acid values, based on epoxy-novalocs in the presence of three different comonomers (styrene, methyl acrylate and butyl acrylate) as reactive diluents. It presents a special account of the optimization of fabrication techniques of glass fiber-reinforced vinyl ester resin composites. It outlines optimum reaction conditions such as temperature, time, monomer type and initiator concentration. The experimental plan consisted of preparation of vinyl ester resin followed by the composite samples. Mechanical characterization was done and a comparison was made between the different samples. It was found that these composites have fairly good tensile and flexural properties. The composites with styrene and butyl acrylate as co-monomers had similar tensile strength which was higher than that of the composite with methyl acrylate. Hardness values of the three composites were almost the same without any significant effect of the comonomer type. Volumetric wear rate was estimated for these samples under various test conditions. A steady wear rate regime after certain amount of sliding was observed all the three cases. [ABSTRACT FROM AUTHOR]

The E glass woven fabrics have been used as a reinforcing agent with amine terminated poly(ethylene glycol) benzoate (ATPEGB) modified epoxy as a matrix, for the preparation of fiber reinforced plastic (FRP) composites. The composite materials so obtained were subjected to dynamic mechanical analysis at a fixed frequency of 1 Hz. The volume fraction of glass was about 0.45. The concentration of ATPEGB in the matrix was varied gradually from 0 to 30 phr (phr stands for parts per hundred parts of resin). To investigate the effect of ATPEGB concentration on the dynamic mechanical properties of the composites, it was found that the tan δ peak temperature and storage modulus gradually decrease with incorporation of ATPEGB. However, the tan δ peak value increases up to 10 phr of ATPEGB concentration and decreases thereafter. Flexural strength of the composites increases slightly up to 10 phr of ATPEGB concentration and decreases thereafter. However, the impact strength of the composites increases significantly up to 10 phr of ATPEGB concentration and decreases thereafter. Scanning electron microscope (SEM) analysis of the fracture surface indicates massive plastic deformation in modified epoxy-based composites. [ABSTRACT FROM AUTHOR]

Acrylonitrile butadiene styrene (ABS)/short glass fiber (SGF) composites were prepared. The effect of fiber volume fraction on the properties of composites was investigated, and test results were compared with theorical equations. SEM micrographs confirmed the reports in other studies that the adhesion between ABS and neat glass fiber is poor. Silane coupling agents with different organofunctional groups were used to improve the interface. The role of these coupling agents was studied by comparing processability, mechanical and physical properties of the composites containing different silane-treated glass fibers. It seems that using coupling agents, especially those with more effective functional groups, reduces the deviation of properties from theory. The affinity of different functional groups to ABS, as well as the strength of chemical and physical bandings formed during the reaction of silane modification, decides the effectiveness of the relative coupling agent. By properties and morphology analysis we concluded that tricholorovinyl silane seems to be the best coupling agent, for this composite. This conclusion is supported by the theorical possibility of forming stronger bands at the interface for this specific coupling agent. [ABSTRACT FROM AUTHOR]

Different samples of acrylonitrile-butadiene-styrene (ABS)/short glass fiber (SGF) composites were prepared. Varying processing conditions such as rotor rate, fiber volume, coupling agent type and amount, and also temperature were applied in order to investigate the effect of different factors on the final properties of the composite produced. All samples were tested physically, mechanically, and morphologically to investigate the effect of varying parameters mentioned above. The best fiber concentration, coupling agent, and temperature were found in a 30 wt% SGF composite coupled with 3 wt% of fiber tricholorovinyle silane and processed at 190°C (rotor rate=80 rpm) which showed the best properties compared with other samples. [ABSTRACT FROM AUTHOR]

Solid particle erosion of polymer composites is a complex surface damage process, strongly affected by material properties and operational conditions. To avoid repeated experimentation, it is important to develop predictive equations to assess material loss due to erosion wear under any impact conditions. This paper presents the development of a mathematical model for estimating erosion damage caused by solid particle impact on flyash filled glass fiber reinforced polyester composites. The model is based upon conservation of particle kinetic energy and relates the erosion rate with composite properties and test conditions. Another correlation derived from the results of Taguchi experimental design is proposed as a predictive equation for erosion wear of these fiber reinforced composites. Further, considering the complexity and high degree of nonlinearity in the erosion process, an artificial neural networks (ANN) technique is implemented as an effective tool for prediction of wear response of these composites in a larger space. Finally, the results of a mathematical model and the ANN model are compared with those obtained from experimentation. [ABSTRACT FROM AUTHOR]

Glass fiber reinforced vinyl ester polymer composites filled with clay particles were synthesized by a hand lay-up technique with the addition of methy ethyl ketone peroxide (MEKP), cobalt napthalate and benzoyl peroxide. Mechanical and thermal properties of vinyl ester-glass fiber composite and clay particles dispersed vinyl-glass fiber hybrids were investigated in the present work. The hybridization effect of nanoclay dispersion in vinyl ester-fiber composite was discussed. Enhanced mechanical, thermal and vibration properties were observed in nanoclay dispersed composites over vinyl ester-glass fiber composite. [ABSTRACT FROM AUTHOR]

A new flame retardant (FR) was synthesized by using melamine, phosphoric acid and zinc oxide as raw materials. The obtained zinc-ion modified melamine polyphosphate (Zn-MPP) was used as an intumescent flame retardant in glass fiber reinforced polyamide 66 (PA66/GF). The effect of Zn-MPP on flame retardancy, thermal degradation and mechanical properties of intumescent flame retardant reinforced polyamide 66 system (PA66/GF/Zn-MPP) has been investigated. The results demonstrated that Zn-MPP is very effective in flame retardancy of PA66/GF. The limited oxygen index (LOI) value of PA66/GF/Zn-MPP reaches 39.2% when the Zn-MPP loading is 25 wt% in PA66/GF. It was also found that when the Zn-MPP loading is only 22 wt% in PA66/GF, the flame retardancy of PA66/GF/FR can still pass V-0 rating, and its LOI value also reaches 37.8%. TGA data obtained in pure nitrogen demonstrated that Zn-MPP has a good ability of char formation itself, and Zn-MPP shows a high initial temperature of the thermal degradation. It was found that Zn-MPP is comparatively stable in the range of processing temperatures of PA66 and is suitable for flame retarding glass fiber reinforced PA66. The PA66/GF/Zn-MPP (22%) has good properties with flame retardancy UL 94 V-0 rating (1.6 mm), tensile strength 129.4 MPa, flexural strength 185.0 MPa, and notched impact strength 7.0 kJ m-2. [ABSTRACT FROM AUTHOR]

The influence of different conditions on the mechanical properties of short coir fiber reinforced polymer composites as well as glass fiber reinforced polymer composites have been analyzed and compared. Fiber length of 20 mm was found to be optimum for the best result. It is observed that the filler loading of 30 phr was most suitable for best results. Degradation studies were carried out in different solvents like 10% NaOH, 1 N HCl, and 10% NaCl and water. The effect of these solvents and water on the mechanical properties of the composites was studied in detail. The deterioration of mechanical properties of the coir/PE and glass/PE composites by environmental weathering was also studied. [ABSTRACT FROM AUTHOR]

A new technique called rubber pressure molding (RPM), has been developed to fabricate fiber reinforced plastic (FRP) products from glass fiber/polyester resin. The technique is based on the matching die set, where the die is made from mild steel and the punch from a flexible rubber-like material, i.e., butyl rubber, to apply hydrostatic pressure on the various surfaces of a complex shaped product. A split steel die and rubber punch are designed and fabricated to prepare the FRP product. The same split die is also used to cast the rubber punch. Using this new technique, an FRP product called a flanged cone is made from glass fiber. Burn test, coin test, scanning electron microscopy (SEM), and mechanical tests like interlaminar fracture toughness, interlaminar shear test, tension test, etc. were carried out to ascertain the fiber content, void content, presence of delamination, bonding between fiber and resin, microstructure, and mechanical properties. These properties were also compared with FRP components made by the conventional technique to evaluate its performance in the structural applications. It is found that the interlaminar fracture toughness of the specimens made by RPM is 10% higher than the specimens made by the conventional method. The tensile strength of the specimen made by RPM technique is 27% more than the specimen made by the conventional method, whereas tensile modulus and Poisson's ratio are in agreement. Furthermore, the interlaminar shear strength of the specimen made by RPM technique is 33% higher than the specimens made by the conventional method. [ABSTRACT FROM AUTHOR]

The effects of curing conditions on the mechanical properties of glass fiber reinforced epoxy composites under different fiber prestressing levels were quantitatively studied. The composite samples were prepared with silica particle modified continuous E-glass fibers, epoxy resin matrix, fiber prestressing and step curing processing. Room temperature cured and isothermal high temperature cured composite samples, with the same content and structure, were made to study the difference of three curing conditions on a quantitative level. Based on the test results of flexural, shear, and impact properties of the composite samples, it was found that the step curing procedure generates composite samples with up to 47% and 14% increased properties than room temperature cured and isothermal high temperature cured samples, respectively, when manufactured under the same fiber prestressing level. The possibility of generating an optimum residual stress within the samples during processing is proposed and discussed to explain the contribution of the step curing process to the composite properties. [ABSTRACT FROM AUTHOR]

This study reports the method of recovery of glass fibers from glass/epoxy composites through the solvent method. It is possible to decompose epoxy resin with a yield of more than 99 wt% soluble products in a nitric acid solution (8 M) at 90°C for 5 h. The decomposition rate of epoxy resin increases with an increase in temperature and concentration of acid solution. The glass fibers can be recovered with very little contamination and they have a tensile strength reduction of 3.5% under decomposition conditions of T=70°C, t=250h, C=6M and α=6g/100mL. These fibers can be used as reinforcement to prepare new composites. The interlaminar shear strength (ILSS) of recovered short fiber-reinforced composites produce strength reductions of only 2.5% compared with pristine composites. [ABSTRACT FROM AUTHOR]

Durability of fiber reinforced polymer composites (FRP) are controlled by the durability of their constituents: reinforcement fibers, resin matrices, and the status of interfaces. A great deal of research has been focused on attempting to assess the relationship between interracial structure and properties of fiber matrix composites. It is at the interracial area where stress concentration develops because of differences in the thermal expansion coefficients between the reinforcement and the matrix phase. A significant mismatch in the environmentally induced degradation of matrix and fiber leads to the evolution of localized stress and strain fields in the FRP composite. The present investigation aims to study the effects of changing hygrothermal conditioning cycles (either by changing relative humidity (RH) and keeping the temperature constant, or by changing the temperature while RH the same is maintained) on moisture gain/loss kinetics and on interlaminar shear strength (ILSS) of varied weight fraction glass fiber reinforced epoxy and polyester matrices composites. The mechanical assessment is extended to evaluate the loading rate sensitivity of hygrothermally shocked glass/epoxy and glass/polyester laminates at 2 and 50mm/min crosshead speeds, respectively. Observations on absorption/desorption kinetics are noticed to be dependent on the nature of hygrothermal shock cycle and on the weight fraction of fiber reinforcement. The results of mechanical performance are statistically significant at different stages of conditioning. Shear values are found to be greater at higher crosshead speed for all undertaken situations. Mechanical responses are observed to be dependent on the matrix resin and the type of hygrothermal shock cycle. Very little and limited literature is open to address the important interactions of polymer composites with this kind of realistic environmental situation. [ABSTRACT FROM AUTHOR]

The glass fiber (GF) reinforced epoxy composite samples used in this study are prepared by four different standardized methods, designated as Methods A, B, C, and D. The GF that is modified with silica particles and prestressed during curing in the composite system (Method D) is proved to be significantly superior as a potential candidate material for use in high impact applications. The impact property of the so-finished composite samples is compared, in turn, with other composite samples prepared by the other methods. There are clean fiber reinforced epoxy composite (Method A), modified GF reinforced epoxy composite (Method B), and prestressed clean GF reinforced epoxy composite (Method C). The results indicate that the impact property of the composites prepared by this novel Method D is greater by up to 100% in comparison with Method A and by lesser but, significant, amounts by the other two methods. [ABSTRACT FROM AUTHOR]

Jute fiber (Hessian cloth) and E-glass fiber (mat)-reinforced, unsaturated polyester (USP) resin along with additives and initiator, composites are prepared by the hand layup technique at room temperature (25°C). Jute fiber content in the composites is optimized with the extent of mechanical properties, and composites with 25% jute show higher mechanical properties. The mechanical properties are found to increase with the incorporation of dissimilar portions of glass fiber into the jute fiber-reinforced composite. Among all the resulting hybrid composites, the composite with a jute to glass ratio of 1 : 3 demonstrates improved mechanical properties, such as tensile strength (TS) 125%, tensile modulus (TM) 49%, bending strength (BS) 162%, and bending modulus (BM) 235% over untreated jute composite. To further improve the properties, the surface of jute and glass fiber is irradiated under UV radiation of different intensities. UV pretreated jute and glass fibers (1:3) at optimum intensities show the highest mechanical properties, such as TS 70%, TM 33%, BS 40%, and BM 43% compared to untreated jute-and glass-based hybrid composites. UV-modified jute/glass-reinforced hybrid composites also show the best of Charpy impact strength (40k J/m²). The interfacial adhesion between jute/glass and USP is monitored by a scanning electronic microscope (SEM). [ABSTRACT FROM AUTHOR]

The objective of this study is to develop a new method of manufacturing glass fiber reinforced epoxy composites and to quantitatively show that the properties of such a new material are superior to that of a conventional fiber reinforced polymer composite of the same material base composition. To achieve this objective, the glass fiber (GF) reinforced epoxy composite samples are prepared in four different ways: Method A, using 'clean' GF as the reinforcement (i.e., with no modification or additional treatment to the as-received fiber); Method B, modifying the surface of the GF with silica particles before applying in the composite system; Method C, prestressing the clean GF during the curing procedure of the composite; and Method D, prestressing the silica modified GF during the curing procedure of the composite. Preparation by Method D is the newly developed method. The finished composite samples are tested by the three-point bend test and the short-beam shear test under ASTM standard conditions. The results indicate that the composites prepared by the new method, which include the GF surface modification and the GF prestressing preparation conditions, have an excellent combination of properties when compared to the specimens made by the other three methods. [ABSTRACT FROM AUTHOR]

The present literature suggests the need for investigating and characterizing the freeze-thaw response of polymer composites under different loading rates and also at ambient and sub-ambient temperatures. The present experiment has been carried out with three different weight fractions (i.e., 0.55, 0.6, and 0.65) of glass fiber-reinforced polyester composites. The short beam shear specimens are suddenly exposed to -80°C for 2 h and then a three-point bend test is conducted instantaneously at this temperature. Another batch of samples is allowed to thaw at ambient temperature for 1 h and tested on flexural mode at ambient temperature. The testing was carried out for a range of 0.5-500mm/min crosshead speed. The shear strengths at cryogenic temperature and thawing temperature are compared with the room temperature-tested data of the shear value of laminates. [ABSTRACT FROM AUTHOR]

Degradation of glass fiber-reinforced polyester composite by hydrothermal shock cycles is studied experimentally. The interface/interphase in glass fiber composites is assumed to be a polymer film, thus, it may be susceptible to perish through environmental shock. Glass fibers of 55, 60, and 65 wt% are used to fabricate polyester matrix polymer composites. The test specimens are first treated in a water bath of 50 °C for 30 min and then immediately immersed in another water bath at 100°C for the same time. The treatment is repeated for different cycles. The short beam shear (SBS) test is performed at room temperature on the conditioned samples for two different crosshead speeds (2 and 50mm/min). The objective of the experiment is to assess the deteriorative effect of hydrothermal shock on the interfacial bonding of varied weight fraction constituents in the composite. The fiber-matrix interfacial damage is reflected in the three-point SBS test. The fall in shear values is observed to be 19-27%, depending on the volume fraction of constituents. The variation in loading speeds is taken into consideration for the assessment of interlaminar shear strength (ILSS). [ABSTRACT FROM AUTHOR]

Many theories point out the complexity of the phenomena that manifest at the fiber-matrix interface or interphase. The interphase in glass fiber composites is reasonably reported to be a film, which is also a polymer. Glass fibers of 55, 60, and 65 wt% are used to fabricate epoxy matrix polymer composites. The test specimens are treated first at 50°C in a water bath for 30 min and then immediately immersed in another water bath at 100°C for the same time. The hydrothermal treatment was carried out for different cycles. The three-point bend short beam shear test was performed on the conditioned samples for two different crosshead speeds (2 and 50 mm/min). The aim of the experiment is to assess the weakening effect of thermal shock and fatigue during hydrothermal aging on the interlaminar adhesion of varied weight fraction constituents in the composite. The variations in loading speed and the moisture content were taken into consideration for the assessment of interface-matrix damage by the cyclic conditioning. [ABSTRACT FROM AUTHOR]

Glass-fiber-reinforced unsaturated polyester and epoxy resin composites were exposed to 75°C temperature gradient thermal shock for ten times in different stages of conditioning times. The other lot of short-beam shear specimens were conditioned with a thermal shock of again 75°C temperature gradient for the different cycles. The three-point bend test was performed on the conditioned specimens to evaluate the value of interlaminar shear strength. These conditionings may induce matrix cracking because of large misfit strain. The present experiments aim to study the fiber--matrix debonding effect of thermal shock--thermal fatigue, post-curing hardening phenomena of thermal conditioning, and also the mechanical keying factor of sub-zero conditioning. [ABSTRACT FROM AUTHOR]

The variations of flexural strength and flexural modulus of unsaturated polyester-based sisal/glass hybrid composites with fiber content have been studied. The hybrid composites showed an increase in flexural properties with glass fiber loading. The effects of alkali treatment and silane treatment of fibers on the flexural properties of these sisal/glass hybrid composites have also been studied. No significant effect on the flexural properties has been observed by silane treatment but a small increase in these properties has been observed by alkali treatment. [ABSTRACT FROM AUTHOR]