Hybridisation effect on flexural properties of single- and double-gated injection moulded acrylonitrile butadiene styrene (ABS) filled with short glass fibres and glass beads particles

The present study investigated the effect of hybridisation on flexural strength and modulus of single-gated (SG) and double-gated (DG) injection moulded acrylonitrile butadiene styrene (ABS) polymer reinforced with both short glass fibres (GF) and spherical glass beads (GB). It was observed that flexural strength and modulus of SG and DG ABS/GF/GB hybrids increased with increasing the total concentration of the glass in the hybrid as well as the concentration of glass fibres in the hybrid (χ _f). Results indicated that hybrid flexural properties for both SG and DG mouldings obey the simple rule of mixtures. The presence of weldlines in DG mouldings had a negative effect on flexural properties. It was noted that weldline integrity factor (weld to unweld property ratio) for flexural modulus and strength decreased with increasing the total concentration of the glass in the hybrid. However, whilst weldline integrity factor for flexural modulus decreased with increasing χ _f, weldline integrity factor for flexural strength showed no significant variation with respect χ _f. Weldline integrity factors indicated that the hybrid flexural strength is more affected by the presence of weldline than the hybrid flexural modulus.     

Mechanical properties of injection moulded styrene maleic anhydride (SMA) Part II Influence of short glass fibres and weldlines

The dependence of the various mechanical and fracture properties on the volume fraction ofshort glass fibres in the styrene maleic anhydride (SMA) polymer was investigated. Special attention has been given to describing the dependence of various mechanical properties on the volume fraction of the glass fibres, f by way of the rule of mixtures. It was found that, strength, elastic modulus and fracture toughness, all follow a simple rule-of-mixtures of the form Qc=Qff+Qm(1–f), where Qc is the measured quantity for the composite, Qm and Qf are the corresponding values for the matrix and the fibre, respectively, and is the overall efficiency of the fibres, taking into account the orientation and the length of the fibres in the composite. It was also found that, while the presence of the weldline had no significant effect upon elastic modulus, its presence significantly reduced tensile strength and the fracture toughness of SMA and its composites. © 1998 Kluwer Academic Publishers     

Thermal and mechanical properties of chemically treated oil palm fiber filled acrylonitrile butadiene styrene composites

In this work, chemical surface treated oil palm fibers, including alkali, maleic and silane pre‐treatments are melt blended and hot compression molded with acrylonitrile butadiene styrene into varying compositions of polymer composites. The effectiveness of the chemical pre‐treatment and fiber dispersion are analyzed with the aid of Fourier‐transform infrared spectrometry and scanning electron microscope while the influences on thermal degradation and mechanical properties of the resulting composites are analyzed through thermal gravimetric analysis and tensile test respectively. Differential thermogravimetric analysis result show that alkali, maleic and silane pre‐treatments could lower the onset thermal degradation temperature of oil palm fiber filled acrylonitrile butadiene styrene composites. The tensile test results show that chemically treated oil palm fiber filled acrylonitrile butadiene styrene composites attained enhancement in tensile strength as compared to untreated counterpart. Scanning electron microscopy observations on fracture surfaces of oil palm fiber filled acrylonitrile butadiene styrene composites found that the reinforcing efficiency of chemically treated oil palm fiber could be further increased by improving interfacial bonding between oil palm fiber and acrylonitrile butadiene styrene.     

Tensile and flexural properties of injection-moulded short glass fibre and glass bead ABS composites in the presence of weldlines

The effect of weldline on tensile and flexural properties of ABS reinforced with short glass fibres (ABS/GF) and spherical glass beads (ABS/GB) was investigated as a function of glass fibre and glass bead concentrations. The weldline was formed in the moulded specimens by direct impingement of two opposing melt fronts (i.e. cold weld). It was found that elastic modulus of ABS/GF composites, with or without weldlines increased linearly with increasing volume fraction of fibres (ϕ_f), according to the rule-of-mixtures for moduli. The presence of weldline reduced tensile and flexural modulus of the ABS/GF composites. Weldline integrity factor for elastic modulus of ABS/GF composites decreased linearly with increasing ϕ_f. Results showed that tensile and flexural strength of ABS/GF increased with increasing ϕ_f in a nonlinear fashion. Flexural strength was consistently greater than tensile strength for the same ϕ_f. Weldline affected both strengths in a significant way; weldline integrity factor decreased with increasing ϕ_f and was independent of loading mode. Tensile and flexural modulus of ABS/GB composites increased linearly with increasing volume fraction of glass beads (ϕ_b), showing no loading mode dependency. Although modulus of the ABS/GB system was not affected significantly by the weldline, its strength was affected, and more so in flexure than in tension. Weld and unweld strengths decreased with increasing ϕ_b in both tension and flexure according to Piggott and Leidner relationship; for the same ϕ_b, flexural strength was always greater than tensile strength. Weldline integrity factor for tensile strength of ABS/GF system was considerably lower than that for ABS/GB system but weldline integrity factor for flexural strength was almost the same for the two composite systems.     

短玻纤增强丙烯腈-丁二烯-苯乙烯共聚物的制备及性能

以丙烯腈-丁二烯-苯乙烯共聚物(ABS)及短玻璃纤维(SGF)为原料, 以苯乙烯-马来酸酐共聚物(SMA)和环氧树脂(EP)为界面相容剂, 制备了SGF/SMA-EP-ABS复合材料。用扫描电镜(SEM)、 动态力学热分析(DMTA)等研究了界面相容剂对SGF增强ABS复合材料力学性能及界面粘结性能的影响。结果表明:加入SMA或EP, SGF增强ABS复合材料的力学性能明显提高; SMA与EP同时加入具有明显的协同效果, 使复合材料的性能更为优越。当SGF加入质量分数为30%时, SGF/SMA-EP-ABS复合材料的拉伸强度、 弯曲强度、 冲击强度较未添加界面相容剂时分别提高了56%、 42%、 79%。SEM和DMTA测试表明, 加入SMA和环氧树脂后, SGF与ABS基体之间的界面粘结性能得到很大改善。      

Superior mechanical and electrical properties of multiwall carbon nanotube reinforced acrylonitrile butadiene styrene high performance composites

In-house synthesized multiwall carbon nanotubes (MWCNTs) have been dispersed in acrylonitrile butadiene styrene (ABS) using a micro twin-screw extruder with back flow channel. The electrical and mechanical properties of MWCNTs in ABS with different wt% have been studied. Incorporation of only 3 wt. % MWCNTs in ABS leads to significant enhancement in the tensile strength (up to 69.4 MPa) which was equivalent to 29% increase over pure ABS. The effect of MWCNTs on the structural behaviour of ABS under tensile loading showed a ductile to brittle transition with increase concentration of MWCNTs. The results of enhanced mechanical properties were well supported by micro Raman spectroscopic and scanning electron microscopic studies. In addition to the mechanical properties, electrical conductivity of these composites increased from 10⁻¹² to 10⁻⁵ Scm⁻¹ showing an improvement of ∼7 orders of magnitude. Due to significant improvement in the electrical conductivity, EMI shielding effectiveness of the composites is achieved up to −39 dB for 10 wt. % loaded MWCNTs/ABS indicating the usefulness of this material for EMI shielding in the Ku-band. The mechanism of improvement in EMI shielding effectiveness is discussed by resolving their contribution in absorption and reflection loss. This material can be used as high-strength EMI shielding material.     

Preparation and properties of mid-infrared glass fibres and poly (chlorotrifluoroethylene) composites

Fluorophosphate-glass-fibre-reinforced poly(chlorotrifluoroethylene) (PCTFE) composites with a transmittance of 80% from 0.4 to 3.7 μm were prepared. The transparent PCTFE composites transmit light to longer wavelengths and have a better chemical resistance to organic solvents (60–70% transmittance after immersing in p-xylene for 24 h) than transparent poly(methyl methacrylate) composites do. The tensile strength of the PCTFE increased by about 20% when it contained 1.1 vol% of unidirectional fluorophosphate glass fibre. The method for preparing the glass fibres and the composites is also described. This revised version was published online in November 2006 with corrections to the Cover Date.     

Temperature and weldline effects on tensile properties of injection moulded short glass fibre PC/ABS polymer composite

The effect of weldline and temperature on tensile properties of injection moulded PC/ABS blend reinforced with different concentration levels of short glass fibres was investigated between 23 and 100 °C. The weldline was formed in the moulded specimens by direct impingement of two opposing melt fronts. It was found that weldline had no significant effect on tensile modulus with weldline integrity factor in the range of 1–0.98. Tensile modulus for both weld and unweld specimens increased linearly with increasing volume fraction of fibres, ϕ_f, and decreased linearly with increasing temperature. Tensile strength of both weld and unweld tensile specimens increased non-linearly with increasing ϕ_f reaching a maximum at ϕ_f≈ 0.16 for specimens without weldline and ϕ_f≈ 0.12 for specimens with weldline. A linear dependence with respect to ϕ_f was found for both weld and unweld tensile strengths for fibre volume fractions in the range 0–0.1. It was found that below the glass transition temperature of the matrix, tensile strength of the composite with and without weldlines decreased linearly with increasing temperature. The weldline integrity factor for tensile strength decreased with increasing ϕ_f, but showed no significant variation with respect to temperature.     

改性淀粉/丁苯橡胶复合材料的制备及性能研究

采用固相法制备了玉米淀粉接枝马来酸酐(MAH)和苯乙烯(St)的共聚物Starch-g-MAH-St(SMS)。采用机械共混法制备了接枝改性淀粉/丁苯橡胶(SMS/SBR)复合材料,研究了复合材料的力学性能、热空气老化性能、动态力学性能以及微观形态。结果表明,SMS/SBR复合材料的力学性能优于未改性淀粉/SBR复合材料和纯SBR。当苯乙烯和MAH单体用量都为原淀粉质量的10 %且SMS的用量为20 g/100 g SBR时,SMS/SBR复合材料的力学性能最佳。经100℃ 热空气老化48 h后,复合材料的拉伸强度仍可达10 MPa。与纯 SBR硫化胶相比,SMS/SBR复合材料的玻璃化转变温度(T_g)降低。微观形态分析显示,淀粉经改性后粒子尺寸减小,在SBR 中的分散性得到了改善,与SBR基体的相容性得到了提高。      

Carbon and glass hierarchical fibers: Influence of carbon nanotubes on tensile,flexural and impact properties of short fiber reinforced composites

Dense carbon nanotubes (CNTs) were grown uniformly on the surface of carbon fibers and glass fibers to create hierarchical fibers by use of floating catalyst chemical vapor deposition. Morphologies of the CNTs were investigated using scanning electronic microscope (SEM) and transmission electron microscope (TEM). Larger diameter dimension and distinct growing mechanism of nanotubes on glass fiber were revealed. Short carbon and glass fiber reinforced polypropylene composites were fabricated using the hierarchical fibers and compared with composites made using neat fibers. Tensile, flexural and impact properties of the composites were measured, which showed evident enhancement in all mechanical properties compared to neat short fiber composites. SEM micrographs of composite fracture surface demonstrated improved adhesion between CNT-coated fiber and the matrix. The enhanced mechanical properties of short fiber composites was attributed to the synergistic effects of CNTs in improving fiber–matrix interfacial properties as well as the CNTs acting as supplemental reinforcement in short fiber-composites.     

Influence of short bamboo/glass fiber on the thermal, dynamic mechanical and rheological properties of polypropylene hybrid composites

The present article summarizes the development of polypropylene-bamboo/glass fiber reinforced hybrid composites (BGRP) using an intermeshing counter rotating twin screw extruder followed by injection molding. Maleic anhydride grafted polypropylene (MAPP) has been used as a coupling agent to improve the interfacial interaction between the fibers and matrix. The crystallization and melting behavior were investigated employing differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) indicates an increase in thermal stability of the matrix polymer with incorporation of bamboo and glass fibers, confirming the effect of hybridization and efficient fiber matrix interfacial adhesion. The dynamic mechanical analysis (DMA) showed an increase in storage modulus (E′) indicating higher stiffness in case of hybrid composites as compared with untreated composites and virgin matrix. The rheological behavior of the hybrid composites has also been studied using time–temperature superposition (TTS) principle and corresponding viscoelastic master curves have been constructed.     

Impact properties of polyurethane and glass fibres reinforced composites

Impact resistance of the polyurethane matrix and composites with glass fibres of various volume fractions was investigated. The theory of linear elastic fracture mechanics (LEFM) was successfully applied to obtain a quantitative assessment of a parameter of toughness, the critical strain energy release rate (G _c), which was determined from the energy (W ^*) required to fracture sharply-notched specimens by taking into account specimen dimensions and notch depth. It is found that the G ^* is not a linear function of reinforcement concentration. The impact resistance with low volume fraction _f=0.045 of glass fibres decreases as compared to that of the matrix. However, with further incorporation of glass fibres, the impact resistance gradually increases, reaching its maximum for the volume fraction _f=0.158. An explanation of this non-linear behaviour is provided in this paper.     

Enhanced electrical conductivity and mechanical properties of ABS/EPDM composites filled with graphene

Acrylonitrile–butadiene–styrene (ABS)/ethylene–propylene–diene monomer (EPDM) composites reinforced with graphene nanoplatelets (GN) were fabricated by the direct melt blending, dried premixing and wet premixing process, respectively. The electrical resistivity, tensile strength, impact strength, microstructure, thermal stability, glass transition temperature and morphology of fracture surface of composites were investigated. In case of direct melt blending process, the maximum tensile strength with minimum impact strength is obtained. But this result is reversed while the fabrication of composites by wet premixing process. SEM results show that GN is prior to distributing in the continuous ABS phase. The percolation threshold could be significantly decreased from 11.8 wt% to 6.6 wt% when prepare composites by wet/dried premixing process instead of melt blending.     

Flexural properties of hybrid composites reinforced by S-2 glass and T700S carbon fibres

A study on the flexural properties of hybrid composites reinforced by S-2 glass and T700S carbon fibres is presented in this paper. Specimens were manufactured following the hand lay-up process in an intra-ply configuration with varying degrees of glass fibres added to the surface of a carbon laminate. These specimens were then tested in the three point bend configuration in accordance with ASTM D790-07 at a span to depth ratio of 32. The failure modes were examined under an optical microscope, and the results show that the dominant failure mode is compressive failure. The flexural modulus, flexural strength and strain to failure were also predicted by finite element analysis. It is seen that flexural modulus decreases with increasing percentage of S-2 glass fibres. Both the experiments and FEA suggest that positive hybrid effects exist by substituting carbon fibres with glass fibres.     

Influence of prepreg conditions on the void occurrence and tensile properties of woven glass fiber-reinforced polyimide composites

The influence of prepreg solvent content on void occurrence in woven glass fiber-reinforced polyimide composites and their tensile properties was studied. A precursor solution of SKYBOND 703 was diluted in an additional solvent (n-methyl pyrrolidone) and the glass woven fabric was immersed in about 40 wt.% polyamic acid, in solvent. Prepregs were dried at 373 K for different time intervals, ranging from 2 to 24 h. Prepregs with varying residual solvent content under each condition were laid up, and their [(0/90)]₄ composite laminates were formed by autoclaving at a hydrostatic pressure of 0.7 MPa. The relationship of drying time with the amount of residual prepreg solvent, as well as with the volume fractions of fiber and voids was investigated. The void geography and content for each composite laminate, and the tensile strength and modulus at room temperature were also evaluated. The results clearly indicated that, depending on the altering residual solvent content in the prepreg, the void geometry and location influenced reduction of the tensile properties of woven fabric composite laminate. An appropriate prepreg resin viscosity during curing, which avoids reduction of the tensile properties, was revealed.     

Poly(acrylonitrile butadiene styrene)/poly(vinylidene fluoride) binary blends films with superior breakdown strength and discharge efficiency

Poly(vinylidene fluoride) (PVDF) ferroelectric polymer with high dielectric constant has been emerged as promising candidate for advanced electrostatic capacitors. However, the intrinsic high ferroelectric loss of PVDF can cause suppressed discharge efficiency, which greatly hinders its applicability. In this work, a polymer-blending approach using linear dielectric component poly(acrylonitrile butadiene styrene) (ABS) is proposed to alleviate the low discharge efficiency issue in PVDF. The ABS-containing high-polarity acrylonitrile monomer demonstrates to show excellent compatibility with PVDF and reduce PVDF ferroelectric domains. With weakened ferroelectric domains coupling, the blends perform significantly enhanced discharge efficiency. For instance, with a moderate discharge energy density of 5.7 J/cm³, a rather high discharge efficiency of 82% can be obtained in blends with a composition content of 50/50 under 400 MV/m while that of PVDF is only 55%. Additionally, the blends exhibit superior operation reliability against pure PVDF, suggesting its feasibility as viable capacitor.

     

Influence of surface treatment of glass fibres on the dynamic mechanical properties of epoxy resin composites

In this study the influence of the interface of differently treated glass fibres in epoxy resin composites is investigated by dynamic mechanical analysis. These results are compared with mechanical measurements of adhesion. It is found that the flexural storage modulus E′ of the composites with improved interfacial bonding is increased over the whole investigated temperature range. Decrease of the magnitude of tan δ at the α-relaxation associates with an improvement of interfacial bonding too. The behaviour differences can only be attributed to interfacial phenomena because all other parameters were kept constant. The dynamic mechanical analysis is an additional possibility for quantifying interfacial interactions.     

Influence of manufacturing parameters on the tensile strengths of hollow and solid glass fibres

Composites reinforced with hollow glass fibres (HGF) have been shown to display improved performance in flexural and compressive loading over materials reinforced with solid fibres. A major drawback associated with hollow fibre composites is reduced reinforcement cross-section for a given fibre volume fraction. It is suggested that the use of optimised manufacturing parameters may allow fibre strengths to be increased, offsetting the inherent strength reduction predicted for hollow fibre composites compared to solid fibre composites. Tensile tests have been performed on batches of hollow and solid fibres with a variety of geometry's to investigate the effects of fibre hollow fraction and manufacturing parameters on fibre strength. Hollow and solid glass fibres drawn under a variety of conditions display tensile strengths which reflect their manufacturing history. A mechanism is proposed whereby differential strains may be locked into the fibre during manufacture. This mechanism may provide an explanation for the strength variations observed. Average tensile strengths for solid and hollow glass fibres appear to increase according to the degree of residual strain differential. The principal manufacturing parameters influencing residual strain differential are draw rate and temperature. Further investigation is suggested into methods for determining heat transport mechanisms within the fibre neck-down zone.     

Hybrid effects on tensile properties of hybrid short-glass-fiber-and short-carbon-fiber-reinforced polypropylene composites

Hybrid composites of polypropylene reinforced with short glass fibers and short carbon fibers were prepared using extrusion compounding and injection molding techniques. The tensile properties of these composites were investigated taking into account the effect of the hybridization by these two types of short fibers. It was noted that the tensile strength and modulus of the hybrid composites increase while the failure strain of the hybrid composites decreases with increasing the relative carbon fiber volume fraction in the mixture. The hybrid effects for the tensile strength and modulus were studied by the rule of hybrid mixtures (RoHM) using the tensile strength and modulus of single-fiber composites, respectively. It was observed that the strength shows a positive deviation from that predicted by the RoHM and hence exhibits a positive hybrid effect. However, the values of the tensile modulus are close to those predicted by the RoHM and thus the modulus shows no existence of a hybrid effect. Moreover, the failure strains of the hybrid composites were found to be higher than the failure strain of the single carbon fiber-reinforced composite, indicating that a positive hybrid effect exists. Explanations for the hybrid effects on the tensile strength and failure strain were finally presented.