Glass Fiber Reinforced Polypropylene Composites Research Articles

Enhanced Interfacial Shear Strength and Critical Energy Release Rate in Single Glass Fiber-Crosslinked Polypropylene Model Microcomposites.

Continuous glass fiber-reinforced polypropylene composites produced by using hybrid yarns show reduced fiber-to-matrix adhesion in comparison to their thermosetting counterparts. Their consolidation involves no curing, and the chemical reactions are limited to the glass fiber surface, the silane coupling agent, and the maleic anhydride-grafted polypropylene. This paper investigates the impact of electron beam crosslinkable toughened polypropylene, alkylene-functionalized single glass fibers, and electron-induced grafting and crosslinking on the local interfacial shear strength and critical energy release rate in single glass fiber polypropylene model microcomposites. A systematic comparison of non-, amino-, alkyl-, and alkylene-functionalized single fibers in virgin, crosslinkable toughened and electron beam crosslinked toughened polypropylene was done in order to study their influence on the local interfacial strength parameters. In comparison to amino-functionalized single glass fibers in polypropylene/maleic anhydride-grafted polypropylene, an enhanced local interfacial shear strength (+20%) and critical energy release rate (+80%) were observed for alkylene-functionalized single glass fibers in electron beam crosslinked toughened polypropylene.

Effects of weathering aging on mechanical and thermal properties of injection molded glass fiber reinforced polypropylene composites

The effect of weathering aging on the degradation behavior of injection molded short glass fiber reinforced polypropylene composites (GFPP) is studied. First, the effect of outdoor weathering on mechanical properties of GFPP composite was investigated by tensile, flexural, and impact tests. Furthermore, to clarify the degradation behavior under natural weathering environments, differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) measurements were carried out to analyze the structural and molecular changes during weathering aging. The results show that weathering aging has a significant influence on changes in mechanical properties, melting temperature and the degree of crystallinity of PG6N1 without added carbon black and UV absorbing agent. Those degradations not only occurred on the surface of GFPP but also proceeded to the inner matrix and interface. However, GFPP GWH42 with added carbon black and UV absorbing agent shows excellent weathering stability.

Loading rate and temperature dependence of flexural behavior in injection-molded glass fiber reinforced polypropylene composites

This paper is concerned with the influence of loading rate/temperature and frequency/temperature on static flexural behavior and dynamic mechanical properties of injection molded glass fiber reinforced polypropylene (GFPP) composites, respectively. Furthermore, the mechanism of long-term durability of PP and GFPP was investigated by the master curve of storage modulus constructed based on the Time-Temperature-Superposition (TTSP) method. Three-point bending tests at various loading rates/temperatures and dynamic mechanical analysis (DMA) at various frequencies/temperatures are performed. The time-temperature dependence of static flexural properties (modulus, E, and strength, σ) and dynamic properties (storage modulus, E’) in PP and GFPP is discussed. The results show that both static flexural behavior and dynamic mechanical behavior of PP and GFPP have significant time-temperature dependent phenomenon, which conforms to the time-temperature equivalence principle. The long-term durability of GFPP depends on the matrix resin rather than the GF reinforcement and its interface at temperatures above the glass transition temperature (Tg).

Effect of nano-OMMTs on mode I and mode II fracture toughness of continuous glass fibre reinforced polypropylene composites

The influence of nano-organic montmorillonites (nano-OMMTs) on mode I and mode II interlaminar fracture toughness of continuous glass fibre reinforced ammonium polyphosphate polypropylene (CGF/PP/APP) composites was experimentally studied in this paper. Nano-OMMTs modified CGF/PP/APP unidirectional prepreg composites were fabricated by hot-melt impregnation process. To investigate the effect of nano-OMMTs on the interlaminar fracture toughness of composites, double cantilever beam (DCB) test and end-notched flexure (ENF) test were conducted to obtain the mode I initiation interlaminar fracture toughness (GIC init.), mode I propagation interlaminar fracture toughness (GIC prop.), and mode II initiation interlaminar fracture toughness (GII C init.) of samples, respectively. Through comparison against to the neat CGF/PP/APP composites, with the addition of 6.5 wt% nano-OMMTs into PP matrix, the GIC init., GIC prop., and GII C init. of composites can be enhanced from 0.502 kJ/m2, 0.746 kJ/m2 and 0.623 kJ/m2 to 0.712 kJ/m2, 1.119 kJ/m2, and 1.195 kJ/m2, respectively. Finally, it was found that nano-OMMTs in matrix can act as “pins”, which could absorb energy in the forms of nano-particles pullout and enhance the interlaminar fracture toughness values in DCB and ENF tests.

Investigation of static, dynamic and thermal behavior of novel glass fabric reinforced polymer composites

The present study investigates the influence of maleic anhydride compatibilizer on the mechanical and thermal behavior of glass fiber reinforced polypropylene composites. The composites were prepared by hot compression molding using novel glass fabric and functionalized polypropylene. The tensile, open-hole tensile, dynamic mechanical analysis and differential scanning calorimetry tests were performed as per ASTM standards to characterize the prepared composites. The experimental test results revealed that the increase in maleic anhydride concentration initially increased the tensile strength and open-hole tensile strength by 20.69% and 9.8%, respectively, and then decreased. Dynamic mechanical analysis showed the higher thermal stability of thermoplastic composites and also confirmed the enhancement of both the modulus, due to the addition of glass fiber. Differential scanning calorimetry results had shown a significant change in the degree of crystallinity behavior. It was observed by scanning electron micrographs that the functionalized polypropylene has improved the interfacial bonding between the constituent materials and was ascertained by Fourier transform analysis.

Effect of novel intumescent flame retardant on mechanical and flame retardant properties of continuous glass fibre reinforced polypropylene composites

In this study, the influence of a novel intumescent flame retardant (IFR) on the mode I interlaminar fracture toughness and flame retardant properties of continuous glass fibre reinforced polypropylene (CGF/PP) composites is presented. The novel IFR system that consists of ammonium polyphosphate/poly (ethanediamine-1, 3, 5 triazine-o-4-amion-2, 2, 6, 6- tetramentylniperidine) (APP/PETAT) was introduced into the CGF/PP unidirectional prepregs (UD) composites by hot-melt impregnation process. Double cantilever beam (DCB) tests were performed to evaluate the mode I interlaminar fracture toughness (GIC) by using modified beam theory (MBT). It was found from the experimental results that compared to the neat CGF/PP composite, the mode I fracture toughness initiation toughness (GIC init.) and propagation toughness (GIC prop.) of CGF/PP/12.5 wt% IFR composites were increased by an average of 99.7% and 119.11% respectively. Meanwhile, samples with 12.5 wt% IFR could self-extinguish with an oxygen concentration of 32.4% and exhibit lower fire spread speed in UL-94 test. Furthermore, the peak of heat release rate (PHRR), total heat release (THR), fire performance index (FPI), and mass loss rate (MLR) tests indicated that IFR could dramatically enhance the flame retardancy of the composites.

Bleached Kraft Eucalyptus Fibers as Reinforcement of Poly(Lactic Acid) for the Development of High-Performance Biocomposites.

Poly(lactic acid) (PLA) is one of the most well-known biopolymers. PLA is bio-based, biocompatible, biodegradable, and easy to produce. This polymer has been used to create natural fiber reinforced composites. However, to produce high-performance and presumably biodegradable composites, the interphase between PLA and natural fibers still requires further study. As such, we aimed to produce PLA-based composites reinforced with a commercial bleached kraft eucalyptus pulp. To become a real alternative, fully biodegradable composites must have similar properties to commercial materials. The results found in this research support the competence of wood fiber reinforced PLA composites to replace other glass fiber reinforced polypropylene composites from a tensile property point of view. Furthermore, the micromechanics analysis showed that obtaining strong interphases between the PLA and the reinforcement is possible without using any coupling agent. This work shows the ability of totally bio-based composites that fulfill the principles of green chemistry to replace composites based on polyolefin and high contents of glass fiber. To the best knowledge of the authors, previous studies obtaining such properties or lower ones involved the use of reagents or the modification of the fiber surfaces.

The evolution of morphology, crystallization and static and dynamic mechanical properties of long glass-fibre–reinforced polypropylene composites under thermo-oxidative ageing

In this work, the static and dynamic mechanical properties, crystallization behaviours, and morphology of long glass-fibre–reinforced polypropylene (PP) composites with thermo-oxidative ageing time from 0 day to 50 days at 120°C were investigated and discussed. The static mechanical properties showed a global decrease in tensile, bending and impact strengths with increasing ageing time. From the results obtained by scanning electronic microscopic observations, interface debonding clearly occurred between the glass fibre and PP matrix in the aged samples. The crystallinity ( Xc) of the composites was analyzed by differential scanning calorimetry; annealing process played the leading role in the early period of ageing, while as ageing progressed, the degradation of PP matrix dominated the ageing process and Xc decreased. The dynamic mechanical analysis results indicated that the storage modulus and glass transition temperature of the composites also decreased with prolonging ageing time. Then, the apparent activation energy ( E) of glass transition was calculated by the Arrhenius equation with different scanning frequencies. A higher value of E was obtained for the samples in the later ageing period, which means a higher energy barrier for glass transition.

Predicting the stress relaxation behavior of glass-fiber reinforced polypropylene composites

It is well established that the addition of short elastic fibers slows the relaxation process in composites, but this phenomenon is not well-understood. Our recent study explained changes in the stress relaxation constant by accounting for the time-dependent interfacial shear stress transfer at the fiber-matrix interface. An analytical model was developed and was successfully compared to finite-element experiments. This approach represents a significant departure from the previously published literature, where the effect of fibers on viscoelasticity was typically attributed to changes in the covalent bonds at the fiber-matrix interface. In the present study, the stress relaxation behavior of glass fiber-reinforced polypropylene composites was experimentally measured and compared to analytical model predictions. Further, the effect of additional covalent bonding at the fiber-matrix interface was studied experimentally by introducing an interfacial coupling agent. Good agreement was obtained between the experimental data and the analytical model and it was concluded that most of the stress relaxation behavior of a composite can be predicted using a model that only accounts for the time-dependent matrix modulus and a time-dependent shear stress transfer efficiency.

Effect of an intumescent flame retardant on the fracture toughness (Mode I), thermal, and flame-retardant properties of continuous glass fibre-reinforced polypropylene composites

ABSTRACTTo solve the ‘wicking actions’ caused by fibre, intumescent flame retardant (IFR) was introduced into the resin of continuous glass fibre-reinforced polypropylene (CGF/PP) composites. The influence of IFR on the properties of composites were investigated by a double cantilever beam test, thermogravimetric analysis, limiting oxygen index, vertical burning test (UL-94), and cone calorimetric test. The results revealed that when the content of IFR was 15 wt-%, the initial Mode I interlaminar fracture toughness (GI init.) and propagation fracture toughness (GI prop.)) were enhanced by 123.2 and 70.26%, respectively, compared to composites with no IFR. The maximum weight loss rate (Tmax) was improved to various degrees. Samples could self-extinguish with an oxygen concentration of 32.4% and achieve a UL-94 V-1 rating. Furthermore, the peak of heat release rate, total heat release, fire performance index, and mass loss rate tests indicated that IFR could dramatically enhance the flame retardancy of the composites.

Effects of thermal‐oxidative aging on the flammability, thermal degradation kinetics and mechanical properties of DBDPE flame retardant long glass fiber reinforced polypropylene composites

Long glass fiber reinforced polypropylene composites containing 2,2′,3,3′,4,4′,5,5′,6,6′‐decabromobibenzy flame retardants (LGF/DBDPE/PP) are prepared by melt blending method. The flame‐retardant properties of the composites with various thermal‐oxidative exposure time (0–50 days) at 140°C were investigated by the limiting oxygen index (LOI) and UL‐94 vertical burning test. The LOI values vary slightly with increasing the aging time, while the UL‐94 level maintains a constant V‐0 rating. The results demonstrate that the flammability of LGF/DBDPE/PP composites can remain at a relatively stable level in long time thermal‐oxidative aging process, which can be attributed to the excellent efficiency of DBDPE fire retardant and the impacts of thermal‐oxidative aging on the thermal stability of the composites turned out to be small. The thermal degradation kinetics of the unaged and aged LGF/DBDPE/PP composites are investigated by the Flynn‐Wall‐Ozawa and Kissinger methods. The obtained activation energy values can further provide objective evidence for revealing the regularities about the flammability of the LGF/DBDPE/PP composites during the thermal‐oxidative aging process. However, the crystallinity and mechanical properties of LGF/DBDPE/PP composites show a slow downtrend after thermal‐oxidative aging. POLYM. COMPOS., 39:E1733–E1741, 2018. © 2018 Society of Plastics Engineers

Study on strain-rate-dependent behaviour and constitutive model of long glass fibre reinforced polypropylene composite

Accurate material model under different strain rates (˙ε) is important for numerical simulations in vehicle design and crashworthiness assessment. Therefore, the objectives of this study are to develop the constitutive model of long glass fibre reinforced polypropylene composite (hereinafter referred to as 'LGFRP') which related to strain rate range of 10-3/s-50/s. Tensile and compression tests are conducted at different strain rates. The experimental results show that the failure strain and ultimate strength increase as increasing strain rate. The elastic modulus is sensitive to strain rate in tensile tests, but less sensitive to strain rate in compression tests. According to the experimental results, a novel constitutive model proposed by the authors is used to represent stress-strain relationship related to strain rate of the LGFRP. The analysis results show that the novel constitutive model agrees well with the experimental results.

Study on strain-rate-dependent behaviour and constitutive model of long glass fibre reinforced polypropylene composite

Accurate material model under different strain rates (˙e) is important for numerical simulations in vehicle design and crashworthiness assessment. Therefore, the objectives of this study are to develop the constitutive model of long glass fibre reinforced polypropylene composite (hereinafter referred to as 'LGFRP') which related to strain rate range of 10-3/s-50/s. Tensile and compression tests are conducted at different strain rates. The experimental results show that the failure strain and ultimate strength increase as increasing strain rate. The elastic modulus is sensitive to strain rate in tensile tests, but less sensitive to strain rate in compression tests. According to the experimental results, a novel constitutive model proposed by the authors is used to represent stress-strain relationship related to strain rate of the LGFRP. The analysis results show that the novel constitutive model agrees well with the experimental results.

GF/PPプレス射出ハイブリッド成形品の機械的特性評価

GF/PPプレス射出ハイブリッド成形品の機械的特性評価

Tribological and mechanical performance of sisal-filled waste carbon and glass fibre hybrid composites

Abstract This study has been carried out to show the use of natural fibres as the potential substitute of synthetic fibres in tribo-composites. The abrasive wear behaviour and mechanical properties of waste sisal/glass, sisal/carbon hybrid fibre reinforced polypropylene (PP) composites were analysed in this study. Results showed that increasing the sisal fibre weight content in the composites increases the coefficient of friction. The abrasion volume of sisal/glass hybrid composites showed significantly lower than those of sisal/carbon hybrid composite for the same hybrid ratios. This means that addition of sisal fibres on waste carbon and glass fibre reinforced PP composites decreased the potential of tribological performance. Although adding of sisal fibres as a natural substitute fibre source to waste short carbon fibre composites lead to inferior properties, an addition of sisal fibres to waste glass composites shows lower densities, comparable mechanical and abrasion volumes than that of waste glass fibre composites. This shows that sisal fibres can be used in place of glass fibres. The scanning electron micrographs of the fracture surfaces show that the wetting interaction of sisal and glass fibre with PP matrix is better than those of the sisal carbon hybrid composites. Furthermore, the worn surfaces of the sisal and its hybrid composites show vertical cracks, loose fragments, micro ploughing and transfer layers.

Glass fiber–reinforced polypropylene composites fabricated by direct fiber feeding injection molding

Abstract This article investigates the effect of process parameters on the mechanical properties of polypropylene-glass fiber (GF/PP) composites made using a new injection molding method known as direct fiber feeding injection molding (DFFIM). In the DFFIM process, continuous fibers are directly guided into the barrel of the injection molding machine through the designed vent and are fed into the polymer melt by the shearing motion of the screw of the injection molding machine during the plasticization process. The DFFIM process improves the fiber length and avoids excessive fiber attrition, resulting in enhanced mechanical properties in the composites. The effect of process parameters on the mechanical properties of manufactured composite specimens is discussed based on the results of tensile tests, three-point flexural tests, and Izod impact tests. Scanning electron microscopy was performed on the fracture surfaces to observe cross-section morphology. There is a fiber agglomeration phenomenon that occurs in the core layer of GF/PP composites made using DFFIM. The number of fiber rovings, number of fiber filaments, matrix feeding speed, and screw speed influence the GF content and distribution in the composites, ultimately affecting the mechanical properties.

Foam injection molding of glass fiber reinforced polypropylene composites with laminate skins

Sandwich panels which consist of discontinuous glass‐fiber reinforced polypropylene composite foam core and continuous glass‐fiber reinforced polypropylene laminate skins were manufactured using industry‐scale equipment in a streamlined manner. The streamlined process included two stages: (1) continuous glass‐fiber reinforced polypropylene laminates as the face skins were produced using an automated, rapid tape layup machine and a hydraulic press, and (2) discontinuous glass‐fiber reinforced polypropylene composite as the core was foam injection‐molded onto the laminate skins (i.e., overmolding), which eliminated bonding process of the foam core and laminate skins, with a physical blowing agent, nitrogen. Optical microscopy results suggested that the increase of void fraction by the core‐back (or mold opening) technique increased the average cell size and cell size distribution, but had little effect on the cell density of the foam core. Mechanical test results suggested that the addition of laminate skins increased the flexural modulus and flexural strength of the solid as well as foam composites significantly. In addition, the material indices were calculated for the sandwich panels manufactured in this study, and the results suggested that the addition of the laminate skins and foaming by the core‐back (or mold opening) technique can greatly reduce the weight of material needed to have the same bending stiffness and maximum bending force. COMPOS., 39:4322–4332, 2018. © 2017 Society of Plastics Engineers

Microdebond test development and interfacial shear strength evaluation of basalt and glass fibre reinforced polypropylene composites

Interfacial adhesion of basalt and glass fibre reinforced polypropylene composites was studied using microdebond testing technique. A focus was put on a simple approach of applying extruded thermoplastic films as a matrix material for microdroplet formation. The ability of different viscosity and thickness polypropylene films to form symmetrical droplets under a temperature range of 200–240℃ was evaluated. Emphasis was put on polypropylene matrix chemistry, silane fibre surface treatment and testing loading rate impact on interfacial performance change in polypropylene-basalt fibre and polypropylene-glass fibre microcomposites. It was found that it was possible to obtain high symmetrical droplet yield out of polypropylene films of melt flow rate 50 and 125 g/10 min and 55–85 µm thickness at 240℃. The presence of maleic anhydride grafted polypropylene coupling agent increased the interfacial shear strength significantly. Microcomposites with glass fibre had higher interfacial shear strength in comparison with the used basalt fibre, mainly due to the difference in their sizing. Various silane-based fibre surface coatings did not result in significant interfacial adhesion changes. Polypropylene-glass fibre microcomposite interfacial shear strength at 0.5, 3.0 and 10.0 mm min–1 loading rates had similar values with high maximum pull-out force scatter at 0.5 and 3.0 mm min–1 loading rates and low scatter at 10.0 mm min–1.

Strength Validation and Morphological studies of Glass Fiber Reinforced with Polypropylene Matrix (GFR/PP) Composites

In the recent years, the polymer composite materials have increased attention and used instead of conventional composites and metals. Many industrial applications and research people prefer thermoplastic polymeric matrices than thermosets due to the very low production time, very low processing cost and availability of thermoplastics. With an increase in demand for composite materials like Glass Fiber Reinforced (GFR) are widely used as reinforcement in thermoplastic polypropylene (PP) matrix to prepare composites. In this study, Glass Fiber Reinforced Polypropylene composites were developed and their mechanical properties were evaluated. In the present work, Glass fiber Reinforced Thermoplastic Polymer Composites is fabricated by Hot press Hydraulic compression molding Technique. The average Strength of thermoplastic polymer matrix with Glass Fiber (GFR/PP) reinforced composite is studied. Test is carried as per the ASTM standards. This study characterizes mechanical properties like Tensile, flexural and impact properties. Scanning electron microscopic (SEM) images of fractured specimen were used for qualitative evaluation of the interfacial properties of Glass Fiber Reinforcement Polypropylene composites.

Finite element analysis of a low-velocity impact test for glass fiber-reinforced polypropylene composites considering mixed-mode interlaminar fracture toughness

In this study, a low-velocity impact test of glass fiber-reinforced polypropylene (GFPP) composites was simulated considering interlaminar fracture toughness. In the simulation, intralaminar and interlaminar damage were modeled using the continuum damage mechanics (CDM) and cohesive zone method (CZM) models, respectively. The B-K criterion was used for the interlaminar damage model along with experimental results, which were obtained from fracture toughness tests of modes I and II and the mixed mode. Low-velocity impact tests were performed to verify the developed damage model, and various characteristics such as delamination and the force–displacement were evaluated. Finally, it was found that the developed damage model with interlaminar fracture toughness can be used to accurately predict the impact behavior of GF/PP composites, including interlaminar delamination.