GF Content Research Articles

Mechanical properties, biosafety, and shearing bonding strength of glass fiber–reinforced PEEK composites used as post-core materials

ObjectiveTo investigate the mechanical properties, biosafety, and shearing bonding strength of glass fibers–reinforced polyether-ether-ketone (PEEK-GF) for post-core materials. MethodsPEEK-GF composites with different glass fiber contents were prepared by extrusion injection and named PEEK-GF30, PEEK-GF40, and PEEK-GF50. Mechanical properties including flexural modulus, flexural strength, Vickers hardness, and compression strength were tested. The cross-sectional morphology was examined using scanning electron microscopy (SEM). Cytotoxicity was studied in vitro with Cell-counting kit-8 (CCK-8). Cell morphology was observed under a microscope. Cell growth on the composites’ surfaces was analyzed with DAPI staining. The shearing bonding strength (SBS) of PEEK-GF50 was assessed after applying different pretreatments. Failure modes were evaluated by microscopy. SEM and contact-angle measurements were performed on the surfaces. Statistical analysis was conducted using one-way ANOVA (P < 0.05). ResultsThe mechanical properties of PEEK-GF composites improved with increased GF content. The PEEK-GF50 group exhibited flexural modulus (17.4 ± 0.5 GPa) close to that of dentin (18.6 GPa) and showed the highest flexural strength (350.0 ± 2.9 MPa), Vickers hardness (47.6 ± 4.5 HV), and compressive strength (264.0 ± 18.0 MPa). The SEM analysis demonstrated that the PEEK matrix combined well with glass fibers. The CCK-8 results confirmed the biosafety of all groups. DAPI staining indicated that cells were growing well on the composites’ surface. The sample that was pretreated with sandblasting and plasma showed the highest SBS (16.0 ± 1.7 MPa). SignificanceThe PEEK-GF composites demonstrated excellent mechanical properties, biosafety, and SBS, and have great potential to serve as post-core materials.

Ultrahigh Flowability and Excellent Mechanical Performance of Glass Fiber/PA6 Composites Prepared by Hyperbranched Polymers

AbstractLightweighting of automotives is crucial for the decrease of fuel and energy consumption, as well as CO2 emission and environmental pollution. Polymer composites, especially the high strength glass fiber/polyamide (GF/PA) composites, have great potential in lightweight; however, they have not been universally accepted due to their insufficient performance. Here, a stearate‐ended hyperbranched polyester (HBP‐12‐n) is designed and high‐performance GF/PA6 composites with high GF content are prepared. The flowability of the composites can be further increased by combining carboxyl‐ended hyperbranched polymer (HyPer C181) with HBP‐12‐n. Compared with unmodified GF/PA6 composites, the melt flow index (MFI) can be increased remarkably to 587% by adding a 0.7 wt% mixture of HBP‐12‐75 and HyPer C181, and the strength and toughness remain competitive. The simultaneous improvement in MFI and impact strength of GF/PA6 composites is the first discovery of this kind, and a synergistic mechanism of amphiphilic bridging‐deformation slipping‐interfacial strengthening of hyperbranched polymers is proposed to account for this phenomenon. This work provides a simple strategy to fabricate GF/PA6 composites with the extensive application for automotive parts and has great prospects in making automotives lightweight and reduction of CO2 emissions.

Vertically interconnected network of graphene fluoride for highly thermoconductive and electrically insulating epoxy composites

AbstractGraphene fluoride (GF), a new graphene derivative, is an excellent candidate for thermal management applications, given its exceptional thermal conductivity and superb insulation properties. However, the fabrication of the vertically aligned graphene fluoride (VA‐GF) sheet network is challenging due to its hydrophobic property and complicated surface modification process. In this work, the freeze‐casting method was used to create VA‐GF scaffolds incorporating polyethyleneimine (PEI) as the dispersing agent and binder. Benefiting from the vertical alignment of the GF scaffold, the epoxy composites exhibited the through‐plane thermal conductivity (TC) of 0.96 W m−1 K−1 at 15 vol% of GF loading, corresponding to 465% and 146% enhancement over pure epoxy and randomly distributed GF/epoxy composites, respectively. As a function of frequency, the electrical conductivity of VA‐GF/epoxy composites was also explored at different filler contents. With increasing GF content and frequency, the electrical conductivity of the composites rose from 10−9 to 10−8 S m−1 between 103 and 106 Hz, demonstrating an insulating property of materials. The vertical alignment of GF in a polymer matrix provides an opportunity for the creation of composites with exceptional thermal conductivity in a through‐plane direction and electrical insulation properties, which promotes the development of thermal management materials for electronic devices.

Preparation of Glass Fiber/Poly(Ether Ether Ketone) Composite Foam with Improved Compressive Strength and Heat Resistance

Glass fiber/poly(ether ether ketone) (GF/PEEK) composite foams with improved compressive strength and heat resistance can be successfully prepared using a simple and environmentally friendly supercritical carbon dioxide (sc‐CO2) foaming technology. The cell morphologies of the foams can be controlled by adjusting the GF content and foaming parameters, including the saturation temperature, saturation time, saturation pressure, and depressurization rate. With a foam density of 0.55 g cm−3, the PEEK‐based composite foam having 30% GF content has a 10% compressive strength of 11.07 MPa, and its density varies negligibly up to 330.0 °C. The GF/PEEK composite foams having high GF contents show significantly better properties than those having low GF contents as a result of the supporting and strengthening effect of the GF in the PEEK cell walls. The GF/PEEK composite foams also show good corrosion resistance. As a result of these properties, the GF/PEEK composite foams are promising high‐performance materials for use in extreme environments.

Preparation and Characterization of Glass-Fiber-Reinforced Modified Polyphenylene Oxide by a Direct Fiber Feeding Extrusion Process

Polyphenylene oxide (PPO) polymers have good mechanical, electrical, and thermal properties, but they have poor processability owing to their quite high melt viscosity. This hinders the manufacturing processes of fiber-reinforced thermoplastics that have enhanced mechanical and physical properties. Although PPO was modified by blending with polystyrene (PS) or polyamide to improve processability, the modified PPO (mPPO) still had a high melt viscosity compared with other polymers. Thus, the fiber-reinforced mPPO is manufactured by compounding with chopped fiber, while various methods are applied to manufacture the fiber-reinforced polypropylene and polyamide in order to improve properties. One of the methods is a direct fiber feeding method, which can keep the longer fiber length because of a direct and continuous roving yarn feeding without chopping. Therefore, the composite manufactured by the direct fiber feeding method is expected to improve the mechanical properties. Hence, this study aims to investigate the feasibility of a direct fiber feeding extrusion process for manufacturing glass-fiber-reinforced mPPO or GFmPPO. The manufactured GF/mPPO composites exhibited increased tensile and flexural properties as the fiber content increased up to 50 wt% of GF owing to the predominant effects of fiber content. Nevertheless, the larger core area in the cross-section micrograph of the tensile specimen of the GF/mPPO composite with 50 wt% of GF was observed to reduce the fiber efficiency factor for tensile strength. Meanwhile, the impact strength of the GF/mPPO composites decreased with increasing GF content. This is attributed to the insufficient fiber length for the impact strength. As the GF content increased, the glass transition temperature slightly decreased. This result was interpreted as being a result of thermal degradation during the extrusion process to manufacture the GF/mPPO masterbatch. The results of the dynamic mechanical analyses, e.g., storage modulus and tan δ, show the good correlation with the increased flexural modulus, the decreased glass transition temperature, and the impact strength as the GF content increased.

Glass fiber reinforced PLA composite with enhanced mechanical properties, thermal behavior, and foaming ability

Polylatic acid (PLA) and PLA foams show a promising prospect for replacing the traditional petroleum-based polymers and foams. However, PLA shows poor ductility, thermal stability and foaming ability, and its application is significantly limited. Herein, silane-modified glass fibers (m-GF) were adopted to improve the mechanical properties, thermal stability, and foaming ability of PLA. PLA/m-GF composites with different GF contents were firstly prepared by twin-screw compounding. Microscopic morphology analysis showed that silane-modified GF has a good bonding with PLA matrix, and increasing GF content led to slight decreased of GF length. Mechanical testing showed that GF led to simultaneously enhanced strength, rigidness, and toughness. The higher the GF content is, the more obvious the reinforcement effect is. With 20 wt% GF, the PLA/m-GF composite shows almost 2-fold enhanced strength and rigidness, and more than 3-fold enhanced impact toughness than the pure PLA. The outstanding mechanical properties arises from the strengthening effect of the GF network skeleton that shows good bonding with PLA matrix. Thermal analysis showed that GF led to increased heat deflection temperature but reduced melt flow index of PLA. Foaming experiments showed that GF can dramatically improve the foaming ability by increasing expansion ratio and refining cellular morphology. Microcellular PLA/m-GF foam with an expansion ratio of up to 20-fold and cell sizes less than 10 μm was achieved. Thus, the strong PLA/m-GF composites and their foams show a promising future in preparing lightweight structural components used in many applications such as automotive and aircraft industries.

Effect of chemical blowing agent, melt temperature, and mold temperature on the fluidity of glass fiber-reinforced polycarbonate in injection molding

ABSTRACTGlass fiber (GF) reinforced polycarbonate (PC) is a composite material that is used in the production of mobile phones, automobiles, LCD monitors, and laptops. With an increase in the GF content, the fluidity of the composite material decreases owing to the flow resistance of GF. A decrease in the fluidity leads to a decrease in processability and moldability; thus, applications of GF reinforced polymers are limited. Here, we investigated whether the fluidity of GF reinforced PC can be increased by using a chemical blowing agent (CBA) and by controlling the melt temperature and mold temperature. In this study, PC was reinforced with GF (45 wt%) using a CBA. Samples of GF reinforced PC were injection molded with respect to varying variables such as CBA content, melt temperature, and mold temperature. We used a spiral mold to compare the fluidity and measured the spiral flow length of the samples. The results indicated that increase in the CBA content increased the fluidity of GF reinforced PC. Furthermore, the results confirmed that the addition of CBA exhibits a considerably higher effect on fluidity than an increase in the melt temperature or mold temperature. Our findings are expected to significantly impact the expanding applications of GF reinforced plastics in the future.

The Effects of Dynamic Loading on Bone Fracture Healing Under Ilizarov Circular Fixators.

Early weight bearing appears to enhance bone fracture healing under Ilizarov circular fixators (ICFs). However, the role of early weight bearing in the healing process remains unclear. This study aims to provide insights into the effects of early weight bearing on healing of bone fractures stabilized with ICFs, with the aid of mathematical modeling. A computational model of fracture site was developed using poro-elastic formulation to simulate the transport of mesenchymal stem cells (MSCs), fibroblasts, chondrocytes, osteoblasts, osteogenic growth factor (OGF), and chondrogenic growth factor (CGF) and MSC differentiation during the early stage of healing, under various combinations of fracture gap sizes (GS), ICF wire pretension forces, and axial loads. 1 h of physiologically relevant cyclic axial loading followed by 23 h of rest in the post-inflammation phase (i.e., callus with granulation tissue) was simulated. The results show that physiologically relevant dynamic loading could significantly enhance cell and growth factor concentrations in the fracture site in a time and spatially dependent manner. 1 h cyclic loading (axial load with amplitude, PA, of 200 N at 1 Hz) increased the content of chondrocytes up to 37% (in all zones of callus), CGF up to 28% (in endosteal and periosteal callus) and OGF up to 50% (in endosteal and cortical callus) by the end of the 24 h period simulated. This suggests that the synergistic effect of dynamic loading-induced advective transport and mechanical stimuli due to early weight bearing is likely to enhance secondary healing. Furthermore, the study suggests that relatively higher PA values or lower ICF wire pretension forces or smaller GS could result in increased chondrocyte and GF content within the callus.

Influence of different compatibilizers on the morphology and properties of PA6/PET/glass fiber composites

ABSTRACTThree kinds of compatibilizers, ethylene–ethyl acrylate copolymer (EEA), ethylene–ethyl acrylate–glycidyl methacrylate copolymer (EAG), and ethene–maleic anhydride–glycidyl methacrylate copolymer (EMG), were introduced to PA6/PET/GF blends for the first time to study the effect of different compatibilizers on composite. EEA, EAG, and EMG showed different effect on the properties of PA6/PET/GF blends. An observation of the GF–resin interface by scanning electronic microscope indicated EAG and EMG enhanced the adhesion of resin to GF, while EEA exhibited no improvement. Differential scanning calorimetry analysis showed that both EMG and EAG increased the degree of crystallinity of the PA6/PET/GF blends, whereas EEA declined. According to dynamic mechanical analysis, EAG, and EMG remarkably increased the storage modulus of composites. For the composites at a given GF content of 30 wt %, EMG increased the tensile strength from 140.6 to 156.3 MPa. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46429.

Microstructure and microwave dielectric properties of Na1/2Sm1/2TiO3 filled PTFE, an environmental friendly composites

A study on Na1/2Sm1/2TiO3 filled and glassfiber reinforced polytetrafluoroethylene (PTFE) composites was described. The GF content was a fixed value of 4 wt%, and the NST content in the composite matrix changed from 26 to 66 wt%. The paper consisted of the manufactural process of the composite and the effects of filler content on the properties of the substrate, such as morphology, moisture absorption, density, dielectric properties and temperature coefficient of dielectric constant. As NST filler loading increased from 26 to 66 wt%, the dielectric constant and loss tangent experienced a continuously increase while the development in τε was opposite. X-Ray Diffraction, FTIR and XPS were used to analyze the microstructure of modified ceramic powder. It was proved that the silane coupling agent has been grafted on the NST surface successfully. At last, the NST/GF filled PTFE composites exhibited good dielectric constant (εr = 4.95), low dielectric loss (tan δ = 0.00147), acceptable water absorption (0.036) and temperature coefficient of dielectric constant (τε = −164) at filler loading of 4 wt% GF and 46 wt% NST.

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.

랜덤상태의 E-유리 단섬유 강화 불포화 폴리에스터 기반 수지 복합재료의 물성 - E-유리 단섬유의 길이와 함량 및 적층수의 영향 -

Abstract : To develop automobile parts, the unsaturated polyester based matrix resin(PR)/reinforcement(randomly orientedchopped E-glass fiber, GF) composites were prepared using sheet molding compound(SMC) compression molding. The effectsof GF length(0.5, 1.0 1.5 and 2.0inch)/content (15, 20, 25, 30wt%) and number of ply(3, 4 and 5) on the specific gravityand mechanical properties of PR/GF composites were investigated in this study. The optimum length of GF was found to beabout 1.0inch for achieving improved mechanical properties(tensile strength and initial modulus). The tensile strength andinitial modulus of composites increased with increasing GF content up to 30wt%, which is favorable content range for SMC.The specific gravity, tensile strength/initial modulus, compressive strength/modulus, flexural strength/modulus and shearstrength increased with increasing the number of ply up to 5, which is the maximum number of ply range for SMC. Theeffectiveness of ply number increased in the flexural strength > shear strength > compressive strength > tensile strength.

Assessment of thermal, morphological, and mechanical properties of poly(methyl methacrylate)/glass flake composites

In this work, poly(methyl methacrylate)/(glass flake) (GF) composites were prepared with different compositions via melt mixing. The effect of the filler ingredient on thermal behavior, morphology, and mechanical and optical properties was investigated by using various techniques, namely differential scanning calorimetry, ultraviolet-visible spectra, mechanical testing, and scanning electron microscopy. For evaluating the level of dispersion of particles, energy dispersive X-ray analysis was performed. Differential scanning calorimetry analysis showed that the glass transition temperature of the samples slightly increased by increasing GF content. Scanning electron microscopy images showed that sized flakes were uniformly dispersed within poly(methyl methacrylate). Energy dispersive X-ray analysis images of samples with different inclusions of GFs showed that the appearance of white dense spots represents the GF particles. It was found that the presence of 0.5 wt% of GF in composites gave more transparency than the other compositions. Furthermore, this composition indicated maximum tensile strength and elongation-at-break values in comparison with the other compositions. J. VINYL ADDIT. TECHNOL., 23:62–69, 2017. © 2015 Society of Plastics Engineers

High toughness hybrid biocomposite process optimization

The process optimization for production of a tough hybrid biocomposite through long fibre thermoplastic direct compounding and moulding process (LFT-D) was investigated with an ultimate goal of high impact strength. High shear mixing – twin screw extrusion – and low shear mixing – single screw extrusion – methods were used for the production of tough hybrid composites. The optimum operating condition was found to be the twin screw extrusion at which feeder to motor speed ratio was 1:10 without breaker and die while feeding the GF before the vent at 100 rpm. The hybrid composite produced accordingly had well dispersed fibres with GF content of 20 wt%, the average length of 2.3 mm, and impact strength of 130 J/m. It can be concluded that toughness was influenced by fibre concentration, length and dispersion.

Tribology of composites produced with recycled GFRP waste

Nowadays, is expected that for most materials to be environmentally friendly. Besides, waste from end-of-life products may be considered a secondary source of materials with an energetic advantage due to its high energy content. This paper deals with the study of friction and wear characteristics of Glass fibre-reinforced polymer (GFRP) composites with polyester/glass fiber (P/GF) waste as filler, replacing the widely used calcium carbonate (CaCO3). Polyester composites based on two or three components, using a combination of polyester, CaCO3, GF, and GF waste, were produced. Pin-on-disc sliding wear test was performed using a polished stainless steel counterface. Roughness, surface energy, and hardness of the composites were characterized before the tests. The GF content (15, 25, 35, and 50 wt.%), the sliding velocity (0.021 and 0.042 m/s), and the normal load (1, 5, and 10 N) were varied. Based on the experimental results, it was observed that the friction coefficient and wear rate were influenced by material composition, surface roughness and energy, adhesive, and abrasive contact mechanisms. P/GF composites having P/GF waste presented enhanced performance considering friction and wear in relation to those with CaCO3 in their composition.

Electromagnetically shielding composite made from carbon fibers, glass fibers, and impact-resistant polypropylene

In order to create polymer composites that can shield machine and instrument casings from electromagnetism and to reclaim waste material, this study melt-blended impact-resistant polypropylene (PP) chips, carbon fibers (CFs; 5, 10, 15, or 20 wt%), and glass fibers (GFs; 0, 5, 7 wt%). This process used a single-screw extruder to make electrically conductive composites. The resulting composites were then evaluated in terms of mechanical properties, electromagnetic shielding effectiveness (EMSE), and surface resistivity. According to experimental results, an increase in CF content increased PP/CF composites’ tensile strength to 29.31 MPa and flexural strength to 38.93 MPa but decreased the impact strength to 49.04 MPa. When the CFs were increased to 15 wt%, the EMSE and surface resistivity of PP/CF composites were above 20 db and 3.3 × 103 Ω/square. For PP/CF/GF composites, with an increase in GF content, the EMSE decreased and the surface resistivity increased.

Morphology, thermal and mechanical properties of glass fiber‐reinforced crosslinkable poly(arylene ether nitrile)

AbstractCrosslinkable poly(arylene ether nitrile)/glass fiber (PEN/GF) composites with high thermal stabilities and mechanical properties were prepared by a economically and environmentally viable method of melt extrusion and injection molding. The feasibility of using PEN/GF composites was investigated by evaluating its morphological, rheological, thermal, and mechanical properties. The morphology shows a good dispersion and strong interfacial interaction between PEN and GF. Thermal studies reveal that the thermal stabilities of PEN/GF are improved significantly with increase of GF content. Mechanical investigation manifested that GFs have strengthening effect (increase in flexural, tensile, and impact strength) on the mechanical performance of PEN composites. Most importantly, crosslinking reaction of PEN/GF composites can further improve their mechanical performances, because a couple of GFs are agglomerated by thermal motion and strong interfacial adhesion and the local agglomeration does not break the global uniform distribution. This work shows that both the enhancement of GF content and the crosslinking reaction of PEN/GF composites are two key factors influencing the thermal and mechanical properties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Strength and cytotoxicity in glass‐fiber‐reinforced denture base resin with changes in the monomer

AbstractGlass fibers (GFs) are often used to strengthen denture base resins. An increase in the GF content can result in severe viscosity, bunching of the GFs, and difficulty in the handling and packing of the poly(methyl methacrylate) (PMMA) resin. To ensure better impregnation of the GFs and improvements in the workability, more methyl methacrylate is needed as the percentage of GFs is increased. The purpose of this study was to determine adequate powder/liquid ratios according to the GF ratios to reinforce with GFs and to evaluate the effect of probable residual monomer on the cytotoxicity and mechanical properties of PMMA denture base resin reinforced with different ratios of GFs. Five specimens were made according to the defined powder/liquid ratios. Ten specimens for each group were prepared with a stainless steel mold. The flexural strength (FS) and elastic modulus were measured with a three‐point bending test in a universal testing machine. To examine changes in toxicity with time, three types of specimens for each group were fabricated and immersed for 0, 24, and 72 h in distilled water after polymerization. The cytotoxicity was evaluated with an agar overlay test. The workability was improved, and the FS and elastic modulus of the denture base resin reinforced with GFs were made significantly higher with increases in the amount of monomer. There was no difference between the control group and the GF‐reinforced groups with regard to the cytotoxicity, despite the increasing monomer concentration. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Influence of GdFeO 3 addition on the physical properties of NaKNbO 3 lead free ferroelectric ceramics

Polycrystalline samples of (1 − x) Na 0.5K 0.5NbO 3–(x) GdFeO 3 (designated as NKN–GF) (x = 0.01, 0.02, 0.04, 0.6 and 0.10), were prepared by a conventional solid-state reaction technique. Preliminary structural studies at room temperature suggest that compounds are formed in a single perovskite phase. Compositions with x = 0.02–0.04 possess orthorhombic structure while for x = 0.06–0.10 show tetragonal structure. The diffraction peaks shift slightly to a higher angle with increasing concentration of x. The ferroelectric phase-transition of these materials, shows a shift in the transition temperature towards the higher-temperature side with increased GF concentration. The magnetization increases with the increase in GF content which is clearly perceptible in the evolution of hysteresis loops indicating that GdFeO 3 doped NKN has introduced ferromagnetic contribution. This may be attributed to variation in the oxygen stoichiometry, doping at different crystallite sites and change in the magnetic anisotropy.

The Study of Surface Properties in Injection Molding (Part-3) —Effect of Molten Polymer Temperature and Pressure in a Mold with Single Cavity—

For the evaluation of the quality of injection molded products, the surface properties is important. It has been shown that a spectrum analysis quantitatively evaluates the surface properties of injection molded products with emboss. In this research, the surface properties showed that the GF content of the injection molded product of a single cavity, molding conditions, and thickness influenced. Moreover, the influence of the resin temperature and pressure was evaluated by using a numerical flow analysis.The result of a new evaluation method in the spectrum analysis proposed by this research corresponded to the observational result for one cavity. Moreover, the resin temperature and the pressure obtained from the numerical analysis showed a good agreement with the tendency to the evaluation results of various conditions.