Properties Of Short Glass Fiber Research Articles

Thermomechanical Characterization of E‐Glass Fiber Reinforced Random Polypropylene

AbstractThe thermomechanical properties of short glass fiber (GF) reinforced polypropylene random copolymer (PPR) composites are investigated. Four composites with different fiber content, namely 10, 15, 20, and 30 wt%, are prepared using melting mixing. For fibers up to 15 wt% the composites exhibit enhanced thermal stability as compared to the random polypropylene. The use of fibers also improve the mechanical strength of the matrix. In particular, PPR/GF30% demonstrates the highest Young modulus, yield strength, and storage modulus values, while PPR/GF10% has the best ductility among the composites. Incorporation of 10 wt% fibers also increases the yield strength and storage modulus of the PPR matrix by approximately 1.6 and 1.2 (for temperatures higher than 60°C) times, respectively. These results suggest that GF reinforced PPR is a composite suitable for advanced technological applications.

Time-temperature-dependent mechanical durability analysis of short (glass) fiber-reinforced polyethylene terephthalate injection molding composites with weld line

The mechanical property and long-term durable life of short fiber composites are inevitably subjected to internal and external influences during molding and afterwards, such as weld, temperature, stress type, and so on. This study was concerned with the influence of weld on mechanical properties of short glass fiber reinforced polyethylene terephthalate injection molding composites and the investigation of their tensile properties at different temperatures and tensile speeds with varying fiber contents. The weld strength was about 50–60% less than the tensile strength at different temperatures and tensile speeds. As the fiber content increased from 15 wt% to 30 wt%, the weld strength was reduced by 10%. The tensile and weld strength were in general inversely proportional to the temperature and linearly proportional to the tensile speed. Tensile modulus showed an inverse association with temperature and a mostly non-linear relation with the tensile speed. The weld line integrity in tensile strength was independent of tensile speed and temperature below the glass transition temperature level. Morphology evaluation testified that the higher test speed emanated better fracture surface fiber–resin adhesion properties with comparatively brittle fracture tensile behavior. The time-temperature superposition principle was applied to find the scope of long-term durability, lifetime prediction and to describe the viscoelastic properties of the welded glass fiber reinforced polyethylene terephthalate composites. An Arrhenius type of shift factor was obtained to fit the tensile strength data which was independent of the fiber contents of the welds. The experimental results can provide a valuable reference for the design and manufacture of short fiber-reinforced composites in long-term durability applications.

Synthesis of a self-assembly amphiphilic sizing agent by RAFT polymerization for improving the interfacial compatibility of short glass fiber-reinforced polypropylene composites

This experimental study focuses on the development of an amphiphilic sizing agent to improve the interfacial adhesion and the mechanical properties of short glass fiber (GF)/polypropylene (PP) composites. To solve the critical compatible issue between the hydrophilic GF and the hydrophobic PP, we strategically utilized the reversible addition-fragmentation chain-transfer (RAFT) polymerization to self-assemble and synthesize an amphiphilic sizing agent. This surfactant-free sizing agent can create hydrogen bonds and electrostatic adsorption on GF surfaces and meanwhile can form molecular entanglements, alkyl cations, and σ-π conjugates with PP matrix. The FT-IR analysis shows that a large number of hydrogen bonds are formed on the sizing agent-GF interface. Additionally, the SEM micrographs of the composite fracture surfaces demonstrate strong interfacial compatibility between the sized-GF and the PP matrix. Comparing with the neat GF/PP composites, the tensile and flexural strength of the sized-GF/PP composites are increased by 25.8% and 33.1%, respectively. Their tensile strength and young's modulus are in close agreement to the analytical calculations. In short, this paper presents a new RAFT-based methodology to develop the amphiphilic sizing agents that are able to improve the interfacial compatibility of GF/PP composites and also can be transferred towards real applications for enhancing the mechanical properties of fiber-reinforced composites.

Elastic properties of injection molded short glass fiber reinforced thermoplastic composites

Depending on fiber size and volume fraction, polymer matrix type, processing temperature, injection speed, etc., short fiber reinforced composites produced by injection molding may exhibit complex fiber concentration, orientation and length distributions at different locations, causing large variations in their mechanical properties. In this work, a representative volume element (RVE) scheme is developed to describe the elastic properties of short glass fiber reinforced PA6,6 composites produced by injection molding. In the RVE formulation, fiber length is assumed to follow a two-parameter Weibull distribution, and a new concept, namely preferential angle, is introduced to account for the preferential alignment of fibers at different locations of injection molded composites. A random sequential insertion algorithm is developed to implement the fiber length distribution and fiber preferential alignment, and finite element method (FEM) is employed to analyze the relations of the elastic properties of RVE with three parameters, that is, the mean length, volume fraction and preferential angle of the fibers. Based on the FEM results, quantitative formulas for these relations are obtained. It is found that the variations in the mean length, volume fraction, and preferential angle of the fibers can cause large variations in elastic moduli and elastic anisotropy of the RVE.

Mechanical Performance of HDPE/UHMWPE Hybrid Composites and Tribological Characterization using Taguchi Method

The physical, mechanical and tribological properties of short glass fiber (SGF) reinforced high density polyethylene/ ultra high molecular weight polyethylene (HDPE/UH MWPE blend) composites and zirconia (ZrO2) filled hybrid composites were studied herein. The interfacial adhesion and the influence of the combined SGF and ZrO2 reinforcements loading were examined to characterize the positive hybrid effect. The physical, mechanical and tribological properties of these hybrid composites were evaluated as per ASTM standards. The presence of SGF and ZrO2 in the HDPE/UHMWPE blends enhanced the tensile strength. The three-body abrasive wear test were also investigated and the specific wear rate was increased with the increase in fiber/filler content. The selected fracture and worn surfaces of the test specimen were investigated by scanning electron microscopy.

RVE modelling of short fiber reinforced thermoplastics with discrete fiber orientation and fiber length distribution

This study presents an analysis of modelling aspects on the effective composite properties of short glass fiber reinforced thermoplastics using representative volume elements (RVE). Although, many investigations were published showing effects of different modelling parameters of RVEs, we further elaborate in this contribution the parameters: influence of fiber packing, fiber shape, bonding of the fibers to the matrix, fiber length distribution and fiber orientation. The knowledge of these influences is used to determine the extent to which the increased modelling accuracy and thus the computational effort leads to an improved RVE’s forecast quality. This objective is achieved by creating and comparing different RVE models of a PBT-GF20 composite. The information required for the RVE models is obtained by experimental characterization of the PBT-GF20 and the PBT matrix material. It can be concluded based on the results of the numerical investigations in conjunction with the experimental tests of the composite that fiber packing, fiber length distribution, fiber orientation and fiber geometry are essential for a precise determination of the effective composite properties.

Wear Behavior of Short Glass Fiber Reinforced Polymer Composite with Nanoclay Modification

This study is aimed to evaluate the effect of nanoclay incorporation on wear properties of short glass fiber reinforced polymer (GFRP) composite. Three different nanoclay contents of 1.0, 3.0 and 5.0wt% were dispersed into epoxy resin using a three-roll mill machine. The fibers were dispersed using mechanical mixer machine. Dry sliding and abrasive wear tests were conducted using pin-on-disc and abrasive resistance tribometer, respectively. The tests were conducted under 30N load and at 300rpm speed for 10000m sliding distance. The addition of nanoclay filler in epoxy polymer has shown improvement towards wear properties of GFRP composite, of up to 65% and 45% under dry sliding and abrasive wear resistance, respectively. The nanoclay appears to improve the microstructural strength leading to better load carrying capacity of the composite, advancing its effect as secondary reinforcement to the polymer composite.

Effect of continuous elongational flow on structure and properties of short glass fiber reinforced polyamide 6 composites

Abstract Short glass fiber (SGF) reinforced polyamide 6 (PA6) composite is an important thermoplastic engineering plastic with excellent properties such as high toughness, high strength, self-lubrication and corrosion resistance. However, due to the characteristics of difficult to disperse and easy to break of the fibers during processing, the application range of the PA6/SGF composite is limited. An innovative twin-eccentric rotor extruder (TERE), which can generate continuous elongation flow, is applied to fabricate the PA6/SGF composites in different fiber content and rotor speed. The fiber length remains good and the fibers are well dispersed in the polymer matrix so that the residual fibers after burn-off form a network interlock structure. That is, the TERE based on continuous elongational flow not only disperses the glass fibers effectively, but also reduces the fiber breakage. Under the action of elongation flow field, the fiber agglomerates undergo a periodic convergence-divergience effect, which forces the fiber agglomerates to separate from each other and disperse homogeneously in the polymer matrix. Interestingly, the charpy impact strength of the composites prepared by the TERE is about double that prepared by the twin-screw extruder (TSE) at each fiber content, which can be attributed to the more efficient fiber dispersion and longer fiber retention length. The thermal oxygen aging property, fatigue property, and creep property analysis also indicate that the TERE has a better dispersion effect than the TSE, and the fibers retain a longer length in the PA6 matrix, thereby providing more excellent service properties.

Influence of screw configuration and processing temperature on the properties of short glass fiber reinforced polypropylene composites

Short glass fiber reinforced polymers are used in many different applications due to their good property profiles. These properties are directly correlated with the fiber length present in the final composite, which can be influenced through the process. Therefore, the aim of this work was to investigate the influence of processing temperature and screw configuration in compounding on the properties of glass fiber reinforced polypropylene. On the one hand, the barrel temperature was varied between 180°C and 260°C and, on the other hand, four different screw configurations were applied using a standard temperature profile. Specimens were produced by injection molding, which were tested via mechanical characterization, density, and fiber length measurements as well as morphology through microscopical analysis. We found, that with higher barrel temperatures and screw configurations bringing lower shear into the melt the glass fiber length is preserved better, thus resulting in improved composite properties. Also the interfacial interaction is not influenced within the investigated parameters, as was checked via the application of a micromechanical model in composite strength. POLYM. ENG. SCI., 59:1552–1559 2019. © 2019 Society of Plastics Engineers

The effect of addition of Multiwall Carbon Nanotubes on the vibration properties of Short Glass Fiber reinforced polypropylene and polypropylene foam composites

The objective of this paper was to investigate the effect of addition of Multiwall Carbon Nanotubes (MWCNTs) with different values of weight percentage (0.5%, 1%, and 1.5%) on the vibration and morphological properties of Short Glass Fiber (SGF) (10, 20, and 30 wt.%) reinforced polypropylene (PP) and the polypropylene foam composites. Nanocomposites were first compounded by using the melt-compounding technique in a twin-screw extruder. Then, azodicarboxamide was added as a foam agent to investigate the foaming behavior of the samples. The free vibration behavior of the samples under clamp-free boundary conditions was studied via Operational Modal Analysis (OMA). In order to confirm the experimental results, the Euler-Bernoulli beam theory was employed to calculate the values of the natural frequencies. The results of analyses indicated that the theoretical natural frequencies had a significant correlation with the experimental results within 18% mean error level. The experimental results showed that addition of SGF particles to the PP and PP foam would significantly increase the natural frequencies, but it would in return decrease the damping factor. The results also indicated that, with addition of MWCNTs to the samples, the damping factor and natural frequencies of the PP and SGF/PP composites would increase. The highest increase in the natural frequencies amounted to 118.8%, which resulted from combination of 20 wt.% SGF and 1 wt.% MWCNT. On the other hand, the highest increase in the damping factor amounted to 68.9%, which resulted from combination of 20 wt.% SGF and 1.5 wt.% MWCNT.

Viscoelasticity of short fiber composites in the time domain: from three-phases micromechanics to finite element analyses

Micromechanical models can be used to calculate the mechanical properties of short glass fiber reinforced thermoplastics. In the present work, a three-step framework is used to validate a three-phases micromechanical model (RDI model) in the time domain, since the analysis of technical components by the finite element method is usually carried out in the time domain. The framework includes mechanical characterization, the implementation of the RDI model and a finite element analysis. The characterization delivers necessary information about the material phases of the composite. A dynamic mechanical analysis is performed to characterize the matrix material in order to obtain the linear viscoelastic properties. The mechanical properties of the matrix–fiber interphase are determined with an inverse calculation. In the second step, the RDI model is used to calculate the frequency depended effective stiffness of the composite. A new developed approach transforms the effective stiffness from the frequency domain into the time domain thus avoiding an explicit inverse Laplace–Carson transformation. In the third step, the RDI model is experimentally validated.

Mechanical and tribological properties of short glass fiber and short carbon fiber reinforced polyethersulfone composites: A comparative study

Abstract The polyethersulfone (PES) composites incorporated with short carbon fibers (SCFs) and short glass fibers (SGFs) were manufactured, and their mechanical and tribological properties were comparatively investigated. The tensile and flexural strengths of SCF/PES composites increase monotonically with increasing the SCF content while those of the SGF/PES composites initially increase dramatically but the strengths approaches a plateau when the SGF content is over 5 vol%. The Young’s and flexural moduli of both SGF/PES and SCF/PES composites exhibit a monotonic increase behavior with increasing the fiber content and achieve the maximum improvements of 128.7%, 227.2%, 165% and 234% with the introduction of 30 vol% short fibers. The addition of SGFs results in a monotonic increase of the friction coefficient and a maximum increase of 48.8% is achieved with 30 vol% SGFs. By contrary, the friction coefficient of SCF/PES composites decreases with the addition of SCFs and a maximum drop of 29.8% compared with that of pure PES is reached with the addition of 20 vol% SCFs. The wear resistance of PES composite is greatly improved by the incorporation of either SGFs or SCFs. The specific wear rates of the PES composites decrease significantly with the addition of short fibers, and the maximum reduction of 71.4% and 95.7% is achieved with the addition of 20 vol% short fibers. When cost is primary consideration while strength, modulus and tribological performance are secondary considerations for end users, SGFs are superior over SCFs; otherwise; SCFs are superior over SGFs.

Mechanical and Thermo-Physical Properties of Short Glass Fiber Reinforced Polybutylene Terephthalate upon Aging in Lubricant/Refrigerant Mixture

In this study, the relationship between structure and mechanical properties of aged PBT composite was investigated. Short glass fiber reinforced PBT composites were subjected to aging tests in environments typically found in hermetic compressors. Diffusion kinetics were addressed by a periodic control of samples weight, and samples aged in oil presented mass variation of 1.2-1.6%, depending on test temperature. Most diffusion curves followed Fickian behavior, and the diffusion coefficient for each condition was obtained. Aging effect was investigated by 3-point bending tests, where samples aged at 180°C presented a significant reduction in all evaluated properties. Control environment induced minor variations, supposedly related to physical aging and increase in crystallinity. Imaging analyses through scanning electronic microscopy (SEM) technique allowed observation of the predominant fracture mechanism. Aged samples presented few or no localized plastic deformation at all, which is in accordance with the lower strain observed in mechanical tests. Differential scanning calorimetry (DSC) analyses proved degree of crystallinity increase for all aged samples, depending mainly on temperature of exposure. Infrared (FTIR) analysis proved the presence of oil absorbed in PBT chemical structure, and it was proposed a method for comparing degree of crystallinity, based on the absorbance bands ratio A0(1458 cm-1)/A0(956 cm-1).

Tensile and flexural properties of graphene oxide coated-short glass fiber reinforced polyethersulfone composites

Abstract It is the first time to report the effects of graphene oxide (GO) coating on the mechanical properties of short glass fiber (SGF) reinforced polymer composites. GO-coated SGF reinforced polyethersulphone (PES) composites are manufactured using extrusion compounding and injection molding techniques. The micro-structures and morphologies of GO and GO-coated SGFs are investigated using scanning electron microscopy, small-angle X-ray scattering, atomic force microscope and Fourier transform infrared techniques. Then, the tensile and flexural properties of the GO-coated SGF/PES composites are systematically studied taking into account the effect of GO coating content. It is observed that both the tensile and flexural strengths are effectively enhanced by the GO coating on the SGF surfaces. This observation is mainly attributed to the enhanced interfacial adhesion between SGFs and PES due to the GO coating. Moreover, the tensile and flexural moduli are also improved by the addition of GO due to the fact that GO has a much higher modulus than the PES matrix.

The Effect of Processing Parameter on Mechanical Properties of Short Glass Fiber Reinforced Polyoxymethylene Composite by Direct Fiber Feeding Injection Molding Process

This research describes the effect of processing parameters as matrix feeding speed, screw rotational speed and cylinder temperature of direct fiber feeding injection-molded process on properties of short glass fiber reinforced polyoxymethylene composite. The increasing of matrix feeding speed at screw rotational speed of 172rpm led to the reduction of fiber loading content and increasing of fiber length. Whereas the higher screw rotational speed impacted on the increasing of fiber loading content and fiber length. However, its tensile properties were lower than the molded at screw rotational speed 172rpm. When fiber loading content over 20wt.%, tensile strength of both conditions reached the same values because the poor fiber distribution especially at screw rotational speed of 258rpm. Then Kelly – Tyson's equation was used to predict their tensile strength. It was found that tensile strength at maximum fiber loading content at screw rotational speed of 172rpm and 258rpm are lower than the calculated strength values around 28.9% and 31.8%, respectively. The effect of cylinder temperature was also elucidated.

Determination of orthotropic properties of glass fibre reinforced thermoplastics using X-ray tomography and multiscale finite element computation

We report a new approach to measure orthotropic properties of short glass fibre reinforced thermoplastics at the macroscopic scale taking into account all microstructural details. 3D imaging technique based on X-ray micro-tomography is used to assess fibrous architecture of an injected part at different positions characterised by different fibre flow histories. Finite element computation is used as a multiscale process, firstly by computing orthotropic parameters at a micro-scale for hundreds of bi-phasic 3D domains composing the macrostructure of the composite at all studied positions. Results are implemented in a second finite element computation as a collection of orthotropic material models composing the heterogeneous structure of the composite.

Effect of fiber orientation, stress state and notch radius on the impact properties of short glass fiber reinforced polypropylene

Short glass fiber reinforced polypropylene (sgf-PP) is increasingly used in the automotive industry with the impact properties as key parameter. Experimentally, the impact behavior strongly depends on the specimen design, test set-up as well as temperature, and thus the characterization method should always be attuned to the occurring impact conditions of the final part. However, in order to deduce some general design criteria for sgf-PP, in this study a wide range of experimental parameters were investigated, specially focusing also on the effect of the governing, local fiber orientation distribution (FOD). Therefore, the effects of stress state (tensile, puncture and bending test), amount of stress concentration (notch radius) and temperature are characterized and discussed. The results proved that, as expected, distinctly different levels of impact strength and different dependencies on notches and notch radii are obtained for the various test set-ups. However, similarities in the temperature dependence are observed for specimens with similar governing fiber orientation.

OS1716 ガラス短繊維強化ポリアミドの衝撃特性に及ぼす繊維径および繊維断面形状の影響

Fiber reinforced plastics is increasingly used to improve fuel efficiency and motion performance of vehicles by weight reduction. Especially, short fiber reinforced thermoplastics is expected to expand its demand because of its superior moldability, productivity, and recyclability. In this study, influences of glass fiber diameter and cross sectional shape on the impact properties of short glass fiber reinforced polyamide were investigated using split Hopkinson pressure bar. In the tensile test, specimen with smaller fiber diameter showed higher tensile strength. Glass fiber reinforced polyamide with flat glass fiber also showed higher strength than that with normal glass fiber. On the other hand, a significant influence of fiber diameter and cross sectional shape on mechanical properties was not found in the compressive test. As a result of the fracture surface observation using scanning electron microscope and the average fiber length measurement, it was revealed that interfacial fracture was a dominant fracture mechanism under tensile loading whereas matrix fracture was dominant under compressive loading. Consequently, the influence of fiber diameter and cross sectional shape on impact properties was different under compressive and tensile loading.

611 短ガラス繊維強化ポリアミド66樹脂の引張特性に及ぼす繊維の配向・体積分率の影響(GS03-3 材料力学)

611 短ガラス繊維強化ポリアミド66樹脂の引張特性に及ぼす繊維の配向・体積分率の影響(GS03-3 材料力学)

Prediction of injection-moulded flax fibre reinforced polypropylene tensile properties through a micro-morphology analysis

Micromechanical models usually applied to predict the mechanical properties of short glass fibre reinforced composites were used to evaluate the Young’s modulus and tensile strength of flax fibre reinforced polypropylene. Due to lack of accuracy between the experimental results and the existing models, a new adjustment to the Kelly-Tyson model was proposed. The changes were based on the understanding of the microstructure obtained in polypropylene/flax fibre composites produced by injection moulding with different flax fibre content. The mechanical properties were interpreted based on real fibre loading, fibre orientation, fibre dimension distribution and morphology of the composites. Lack of fibre/matrix adhesion, strong fibre damage and changes on the crystallization behaviour of polypropylene in the presence of flax fibres affect the mechanical strength, stiffness and elongation of the composites. The Kelly-Tyson’s model used for tensile strength prediction was modified to take into consideration the fibre property variability due to the large distribution of fibre shape ratio induced by the process. Finally, matrix modulus has been adjusted to take into account the change of crystallinity with fibre content. A better description of the mechanical properties is obtained using the proposed approach, resulting indeed in an excellent approximation to the modulus of the composite.