Temperature effect on graphene‐filled interface between glass–carbon hybrid fibers and epoxy resin characterized by fiber‐bundle pull‐out test

The overall mechanical performance of glass–carbon hybrid fibers reinforced epoxy composites depends heavily upon fiber–matrix interfacial properties and the service temperatures. Fiber‐bundle pull‐out tests of glass (GF) and/or carbon fiber (CF) reinforced epoxy composites were carried out at room and elevated temperatures. Graphene nanoplatelets were added in the interfacial region to investigate their influence on the interfacial shear strength (IFSS). Results show that IFSS of specimens with fiber‐bundle number ratio of GF:CF = 1:2 is the largest among the hybrid composites, and a positive hybridization effect is found at elevated temperatures. IFSS of all the specimens decreases with the increasing of test temperatures, while the toughness shows a contrary tendency. As verified by scanning electron microscopy observations, graphene nanoplatelets on fiber surface could enhance the IFSS of pure glass/carbon and hybrid fibers reinforced epoxy composites at higher temperatures significantly. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46263.     

Investigation of mechanical properties of alumina nanoparticle‐loaded hybrid glass/carbon‐fiber‐reinforced epoxy composites

This research work investigates the tensile strength and elastic modulus of the alumina nanoparticles, glass fiber, and carbon fiber reinforced epoxy composites. The first type composites were made by adding 1–5 wt % (in the interval of 1%) of alumina to the epoxy matrix, whereas the second and third categories of composites were made by adding 1–5 wt % short glass, carbon fibers to the matrix. A fourth type of composite has also been synthesized by incorporating both alumina particles (2 wt %) and fibers to the epoxy. Results showed that the longitudinal modulus has significantly improved because of the filler additions. Both tensile strength and modulus are further better for hybrid composites consisting both alumina particles and glass fibers or carbon fibers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39749.     

Hybrid carbon-glass fiber vinyl ester resin composites

Hybrid carbon-glass fiber composites of novolak epoxy-based vinyl ester resins have been investigated. The chemical resistance, the thermo-oxidative stability and the mechanical properties such as tensile strength and tensile modulus, as well as flexural strength and flexural modulus, interlaminar shear strength (ILSS) and impact strength have also been estimated. The combination of glass and carbon fibers in the hybrid turns out to be an excellent mix. These composites have good tensile and flexural properties as well as the good chemical resistance of the carbon fibers and the high impact strength of the glass fibers and also the thermo-oxidative stability of highly aromatic vinyl ester resins based on novolak epoxy.     

Unsaturated polyester‐toughened epoxy composites: Effect of sisal fiber on thermal and dynamic mechanical properties

In the present study, the mechanical and thermal properties of sisal fiber‐reinforced unsaturated polyester (UP)‐toughened epoxy composites were investigated. The sisal fibers were chemically treated with alkali (NaOH) and silane solutions in order to improve the interfacial interaction between fibers and matrix. The chemical composition of resins and fibers was identified by using Fourier‐transform infrared spectroscopy. The UP‐toughened epoxy blends were obtained by mixing UP (5, 10, and 15 wt%) into the epoxy resin. The fiber‐reinforced composites were prepared by incorporating sisal fibers (10, 20, and 30 wt%) within the optimized UP‐toughened epoxy blend. Scanning electron microscopy was used to analyze the morphological changes of the fibers and the adhesion between the fibers and the UP‐toughened epoxy system. The results showed that the tensile and flexural strength of (alkali‐silane)‐treated fiber (30 wt%) ‐reinforced composites increased by 83% and 55%, respectively, as compared with that of UP‐toughened epoxy blend. Moreover, thermogravimetric analysis revealed that the (alkali‐silane)‐treated fiber and its composite exhibited higher thermal stability than the untreated and alkali‐treated fiber systems. An increase in storage modulus and glass transition temperature was observed for the UP‐toughened epoxy matrix on reinforcement with treated fibers. The water uptake behavior of both alkali and alkali‐silane‐treated fiber‐reinforced composites is found to be less as compared with the untreated fiber‐reinforced composite. J. VINYL ADDIT. TECHNOL., 23:188–199, 2017. © 2015 Society of Plastics Engineers     

Microstructural,mechanical, and thermal characteristics of recycled cellulose fiber‐halloysite‐epoxy hybrid nanocomposites

Epoxy hybrid‐nanocomposites reinforced with recycled cellulose fibers (RCF) and halloysite nanotubes (HNTs) have been fabricated and investigated. The dispersion of HNTs was studied by synchrotron radiation diffraction (SRD) and transmission electron microscopy (TEM). The influences of RCF/HNTs dispersion on the mechanical properties and thermal properties of these composites have been characterized in terms of flexural strength, flexural modulus, fracture toughness, impact toughness, impact strength, and thermogravimetric analysis. The fracture surface morphology and toughness mechanisms were investigated by SEM. Results indicated that mechanical properties increased because of the addition of HNTs into the epoxy matrix. Flexural strength, flexural modulus, fracture toughness, and impact toughness increased by 20.8, 72.8, 56.5, and 25.0%, respectively, at 1 wt% HNTs load. The presence of RCF dramatically enhanced flexural strength, fracture toughness, impact strength, and impact toughness of the composites by 160%, 350%, 444%, and 263%, respectively. However, adding HNTs to RCF/epoxy showed only slight enhancements in flexural strength and fracture toughness. The inclusion of 5 wt% HNTs into RCF/epoxy ecocomposites increased the impact toughness by 27.6%. The presence of either HNTs or RCF accelerated the thermal degradation of neat epoxy. However, at high temperature, samples reinforced with RCF and HNTs displayed better thermal stability with increased char residue than neat resin. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers     

Effects of organo‐montmorillonite on the mechanical and morphological properties of epoxy/glass fiber composites

Epoxy composites filled with glass fiber and organo‐montmorillonite (OMMT) were prepared by the hand lay‐up method. The flexural properties of the epoxy/glass fiber/OMMT composites were characterized by a three‐point bending test. The flexural modulus and strength of epoxy/glass fiber were increased significantly in the presence of OMMT. The optimum loading of OMMT in the epoxy/glass fiber composites was attained at 3 wt%, where the improvement in flexural modulus and strength was approximately 66 and 95%, respectively. The fractured surface morphology of the epoxy/glass fiber/OMMT composites was investigated using field emission scanning electron microscopy. It was found that OMMT adheres on the epoxy/glass fiber interface, and this is also supported by evidence from energy dispersive X‐ray analysis. Copyright © 2007 Society of Chemical Industry     

Hybrid multi‐scale epoxy composites containing conventional glass microfibers and electrospun glass nanofibers with improved mechanical properties

A mechanically flexible mat consisting of structurally amorphous SiO₂ (glass) nanofibers was first prepared by electrospinning followed by pyrolysis under optimized conditions and procedures. Thereafter, two types of hybrid multi‐scale epoxy composites were fabricated via the technique of vacuum assisted resin transfer molding. For the first type of composites, six layers of conventional glass microfiber (GF) fabrics were infused with the epoxy resin containing shortened electrospun glass nanofibers (S‐EGNFs). For the second type of composites, five layers of electrospun glass nanofiber mats (EGNF‐mats) were sandwiched between six layers of conventional GF fabrics followed by the infusion of neat epoxy resin. For comparison, the (conventional) epoxy composites with six layers of GF fabrics alone were also fabricated as the control sample. Incorporation of EGNFs (i.e., S‐EGNFs and EGNF‐mats) into GF/epoxy composites led to significant improvements in mechanical properties, while the EGNF‐mats outperformed S‐EGNFs in the reinforcement of resin‐rich interlaminar regions. The composites reinforced with EGNF‐mats exhibited the highest mechanical properties overall; specifically, the impact absorption energy, interlaminar shear strength, flexural strength, flexural modulus, and work of fracture were (1097.3 ± 48.5) J/m, (42.2 ± 1.4) MPa, (387.1 ± 9.9) MPa, (12.9 ± 1.3) GPa, and (30.6 ± 1.8) kJ/m², corresponding to increases of 34.6%, 104.8%, 65.4%, 33.0%, and 56.1% compared to the control sample. This study suggests that EGNFs (particularly flexible EGNF‐mats) would be an innovative type of nanoscale reinforcement for the development of high‐performance structural composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42731.     

Comparison of the role of milled glass and carbon fibers on mechanical properties of (bisphenol A)‐based epoxy composites

The main target of the current work was to study the mechanical properties of milled E‐glass, S‐glass, and high‐strength (carbon fiber)‐reinforced epoxy composites. At first, tensile behavior of the as‐received fibers was evaluated by conducting different tensile tests. Afterwards, the effects of employing an integral blended coupling agent on the performance of the pure epoxy were investigated by microhardness tests and optical microscopic images. Then, the epoxy composites were prepared simply by mixing and stirring 1, 3, and 5 wt% of the milled fibers with the epoxy resin and its hardener. The effects of mixture degassing and addition of the coupling agent to the mixture were examined based on the mechanical properties of the fabricated composites. Also, scanning electron microscope macro‐ and micrographs of the transverse and longitudinal fracture surfaces were used to study the fracture behavior and identify the active toughening mechanisms. The best results were obtained for the degassed and modified milled (carbon fiber epoxy)‐reinforced composite, which enhanced the tensile strength, elongation, Young's modulus, and toughness up to 12%, 17%, 19%, and 27%, respectively. The current study shows that the composite not only is cost effective but also offers better mechanical properties. J. VINYL ADDIT. TECHNOL., 24:130–138, 2018. © 2016 Society of Plastics Engineers     

Hybrid effect on mechanical properties of M40‐T300 carbon fiber reinforced Bisphenol A Dicyanate ester composites

Interply and intraply hybrid composites based on Bisphenol A Dicyanate ester (BADCy), high strength carbon fibers T300, and high modulus carbon fibers M40 were prepared by monofilament dip‐winding and press molding technique. The tensile, flexural, interlaminar shear properties and SEM analysis of the hybrid composites with different fiber content and fiber arrangement were investigated. The results indicated that the mechanical properties of intraply hybrid composites were mainly determined by fiber volume contents. When the ratio of fiber volume content was close to 1:1, the intraply hybrid composites possessed lowest tensile and flexural strength. The mechanical properties of interply hybrid composite mainly depended on the fiber arrangement, instead of the fiber volume contents. The hybrid composites using T300 fiber layout as outside layer possessed high flexural strength and low flexural modulus, which was close to that of T300/BADCy composites. The hybrid composites ([(M40)_x/(T300)_y]_S) using M40 fiber layout as outside layer and T300 fibers in the mid‐plane had high flexural modulus and interlaminar shear strength. POLYM. COMPOS., 2010. © 2010 Society of Plastics Engineers     

Thermal and mechanical properties of hybrid carbon/oxidized polyacrylonitrile fibers‐epoxy composites

Nowadays, hybrid composites are one of the important materials in industry due to their special properties. In this research, hybrid oxidized polyacrylonitrile (PAN) and carbon fibers reinforcement were used in epoxy matrix. The hybrid composites were fabricated using the hand lay‐up technique by placing the reinforcements in different layering sequences. Thermal and mechanical properties of these hybrid composites were investigated by thermal analysis, horizontal burning, tensile and bending tests. The tensile test results indicated that increasing oxidized polyacrylonitrile fibers (OPFs) to carbon fibers ratio decreased tensile strength and elastic modulus but increased failure strain. Hybrid oxidized PAN and carbon fibers reinforcement in composites led to decreasing flexural stress and modulus, and increasing flame retardancy. Thermal analysis results also showed that the maximum rate of mass loss in all composites was 370.6°C. It was also found that the maximum and minimum amounts of char residue at 900°C were related to the composites with four layers of carbon and OPFs, respectively. POLYM. COMPOS., 38:1412–1417, 2017. © 2015 Society of Plastics Engineers     

Enhancement of interlaminar fracture toughness of carbon fiber–epoxy composites using polyamide‐6,6 electrospun nanofibers

In this study, carbon fiber–epoxy composites are interleaved with electrospun polyamide‐6,6 (PA 66) nanofibers to improve their Mode‐I fracture toughness. These nanofibers are directly deposited onto carbon fabrics before composite manufacturing via vacuum infusion. Three‐point bending, tensile, compression, interlaminar shear strength, Charpy impact, and double cantilever beam tests are performed on the reference and PA 66 interleaved specimens to evaluate the effects of PA 66 nanofibers on the mechanical properties of composites. To investigate the effect of nanofiber areal weight density (AWD), nanointerlayers with various AWD are prepared by changing the electrospinning duration. It is found that the electrospun PA 66 nanofibers are very effective in improving Mode‐I toughness and impact resistance, compressive strength, flexural modulus, and strength of the composites. However, these nanofibers cause a decrease in the tensile strength of the composites. The glass‐transition temperature of the composites is not affected by the addition of PA 66 nanofibers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45244.     

Incorporation of silicon dioxide nanoparticles at the carbon fiber‐epoxy matrix interphase and its effect on composite mechanical properties

Functionalized silicon dioxide nanoparticles (nano‐fSiO₂) were uniformly deposited on the surface of carbon fibers (CFs) using a coating process which consisted of immersing the fibers directly in a suspension of nano‐fSiO₂ particles and epoxy monomers in 1‐methyl‐2‐pyrrolidinone (NMP). The 0° flexural properties, 90° flexural properties, and Interlaminar shear strength (ILSS) mechanical properties of unidirectional epoxy composites made with nano‐fSiO₂+epoxy sized carbon fibers, with control fibers, and with epoxy‐only sized fibers were measured and compared. An obvious increase of the fiber/matrix adherence strength was obtained with the nano‐fSiO₂+epoxy coating. The nano‐fSiO₂+epoxy sized CF/epoxy composites showed a relative increase of 15%, 50%, and 22% in comparison to control fibers, for the Interlaminar shear strength, the 90^° flexural strength and the 90° flexural modulus, respectively, but little e difference was measured between the different systems for the 0° flexural properties. The observation of the fracture surfaces by scanning electron microscopy of composite fracture confirmed the improvement of the interfacially dependent mechanical properties. POLYM. COMPOS., 38:1474–1482, 2017. © 2015 Society of Plastics Engineers     

A comparative analysis of woven jute/glass hybrid polymer composite with and without reinforcing of fly ash particles

The objective of this research article is to compare the mechanical and tribological properties of jute‐glass‐fiber‐reinforced epoxy (J‐G‐E) hybrid composites with and without fly ash particulate filler. A dry hand lay‐up technique is used to fabricate all the laminates. The properties including flexural strength, tensile strength, flexural modulus, and erosion behavior of all the composites are evaluated as per American Society for Testing and Materials (ASTM) standards. The fly ash particulate‐filled hybrid composite shows a better mechanical and tribological property. The maximum flexural strength and flexural modulus are obtained for GJGJ+ 5 wt% fly ash filler epoxy composites. Whereas the maximum tensile strength is obtained for GJJG+ 10 wt% fly ash filler epoxy composites. Scanning Electron Microscopy (SEM) analysis also has been carried out to categorize mechanical and tribological behavior of composites. POLYM. COMPOS. 37:658–665, 2016. © 2014 Society of Plastics Engineers     

Concentration effect of γ‐glycidoxypropyltrimethoxysilane on the mechanical properties of glass fiber–epoxy composites

In this study, glass fibers were modified using γ‐glycidoxypropyltrimethoxysilane of different concentrations to improve the interfacial adhesion at interfaces between fibers and matrix. Effects of γ‐glycidoxypropyltrimethoxysilane on mechanical properties and fracture behavior of glass fiber/epoxy composites were investigated experimentally. Mechanical properties of the composites have been investigated by tensile tests, short beam tests, and flexural tests. The short‐beam method was used to measure the interlaminar shear strength (ILSS) of laminates. The tensile and flexural properties of composites were characterized by tensile and three‐point bending tests, respectively. The fracture surfaces of the composites were observed with a scanning electron microscope. On comparing the results obtained for the different concentrations of silane solution, it was found that the 0.5% GPS silane treatment provided the best mechanical properties. The ILSS value of heat‐cleaned glass fiber reinforced composite is enhanced by ∼59% as a result of the glass fiber treatment with 0.5% γ‐GPS. Also, an improvement of about 37% in tensile strength, about 78% in flexural strength of the composite with the 0.5% γ‐GPS treatment of glass fibers was observed. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Mechanical and thermal properties of hierarchical composites enhanced by pristine graphene and graphene oxide nanoinclusions

Epoxy resin nanocomposites incorporated with 0.5, 1, 2, and 4 wt % pristine graphene and modified graphene oxide (GO) nanoflakes were produced and used to fabricate carbon fiber‐reinforced and glass fiber‐reinforced composite panels via vacuum‐assisted resin transfer molding process. Mechanical and thermal properties of the composite panels—called hierarchical graphene composites—were determined according to ASTM standards. It was observed that the studied properties were improved consistently by increasing the amount of nanoinclusions. Particularly, in the presence of 4 wt % GO in the resin, tensile modulus, compressive strength, and flexural modulus of carbon fiber (glass fiber) composites were improved 15% (21%), 34% (84%), and 40% (68%), respectively. Likewise, with inclusion of 4 wt % pristine graphene in the resin, tensile modulus, compressive strength, and flexural modulus of carbon fiber (glass fiber) composites were improved 11% (7%), 30% (77%), and 34% (58%), respectively. Also, thermal conductivity of the carbon fiber (glass fiber) composites with 4% GO inclusion was improved 52% (89%). Similarly, thermal conductivity of the carbon fiber (glass fiber) composites with 4% pristine graphene inclusion was improved 45% (80%). The reported results indicate that both pristine graphene and modified GO nanoflakes are excellent options to enhance the mechanical and thermal properties of fiber‐reinforced polymeric composites and to make them viable replacement materials for metallic parts in different industries, such as wind energy, aerospace, marine, and automotive. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40826.     

Tribological behavior of short‐fiber‐reinforced polyimide composites under dry‐sliding and water‐lubricated conditions

Polyimide composites reinforced with short‐cut fibers such as carbon, glass, and quartz fibers were fabricated by the polymerization of monomer reactants process. The mechanical properties of the composites with different fiber contents were evaluated. The friction and wear properties of the polyimide and its composites were investigated under dry‐sliding and water‐lubricated conditions. The results indicated that the short‐carbon‐fiber‐reinforced polyimide composites had better tensile and flexural strengths and improved tribological properties in comparison with glass‐fiber‐ and quartz‐fiber‐reinforced polyimide composites. The incorporation of short carbon fibers into the polyimide contributed to decreases in the friction coefficient and wear rate under both dry and water‐lubricated conditions and especially under water lubrication because of the boundary lubrication effect of water. The polyimide and its composites were characterized by plastic deformation, microcracking, and spalling under both dry and water‐lubricated conditions, which were significantly abated under the water‐lubricated condition. The glass and quartz fibers were easily abraded and broken; the broken fibers transferred to the mating metal surface and increased the surface roughness of mating stainless steel, which led to the wear rate increasing for the glass‐fiber‐ and quartz‐fiber‐reinforced polyimide composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Mechanical properties of natural fiber hybrid composites based on renewable thermoset resins derived from soybean oil,for use in technical applications

Natural fiber composites are known to have lower mechanical properties than glass or carbon fiber reinforced composites. The hybrid natural fiber composites prepared in this study have relatively good mechanical properties. Different combinations of woven and non‐woven flax fibers were used. The stacking sequence of the fibers was in different orientations, such as 0°, +45°, and 90°. The composites manufactured had good mechanical properties. A tensile strength of about 119 MPa and Young's modulus of about 14 GPa was achieved, with flexural strength and modulus of about 201 MPa and 24 GPa, respectively. For the purposes of comparison, composites were made with a combination of woven fabrics and glass fibers. One ply of a glass fiber mat was sandwiched in the mid‐plane and this increased the tensile strength considerably to 168 MPa. Dynamic mechanical analysis was performed in order to determine the storage and loss modulus and the glass transition temperature of the composites. Microstructural analysis was done with scanning electron microscopy. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Biobased composites prepared by compression molding with a novel thermoset resin from soybean oil and a natural‐fiber reinforcement

Biobased composites were manufactured with a compression‐molding technique. Novel thermoset resins from soybean oil were used as a matrix, and flax fibers were used as reinforcements. The air‐laid fibers were stacked randomly, the woven fabrics were stacked crosswise (0/90°), and impregnation was performed manually. The fiber/resin ratio was 60 : 40. The prepared biobased composites were characterized by impact and flexural testing. Scanning electron microscopy of knife‐cut cross sections of the specimens was also done to investigate the fiber–matrix interface. Thermogravimetric analysis of the composites was carried out to provide indications of thermal stability. Three resins from soybean oil [methacrylated soybean oil, methacrylic anhydride modified soybean oil (MMSO), and acetic anhydride modified soybean oil] were used as matrices. The impact strength of the composites with MMSO resin reinforced with air‐laid flax fibers was 24 kJ/m², whereas that of the MMSO resin reinforced with woven flax fabric was between 24 and 29 kJ/m². The flexural strength of the MMSO resin reinforced with air‐laid flax fibers was between 83 and 118 MPa, and the flexural modulus was between 4 and 6 GPa, whereas the flexural strength of the MMSO resin reinforced with woven fabric was between 90 and 110 MPa, and the flexural modulus was between 4.87 and 6.1 GPa. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Injection‐molded short hemp fiber/glass fiber‐reinforced polypropylene hybrid composites—Mechanical,water absorption and thermal properties

Natural fiber‐based thermoplastic composites are generally lower in strength performance compared to thermoset composites. However, they have the advantage of design flexibility and recycling possibilities. Hybridization with small amounts of synthetic fibers makes these natural fiber composites more suitable for technical applications such as automotive interior parts. Hemp fiber is one of the important lignocellulosic bast fiber and has been used as reinforcement for industrial applications. This study focused on the performance of injection‐molded short hemp fiber and hemp/glass fiber hybrid polypropylene composites. Results showed that hybridization with glass fiber enhanced the performance properties. A value of 101 MPa for flexural strength and 5.5 GPa for the flexural modulus is achieved from a hybrid composite containing 25 wt % of hemp and 15 wt % of glass. Notched Izod impact strength of the hybrid composites exhibited great enhancement (34%). Analysis of fiber length distribution in the composite and fracture surface was performed to study the fiber breakage and fracture mechanism. Thermal properties and resistance to water absorption properties of the hemp fiber composites were improved by hybridization with glass fibers. Overall studies indicated that the short hemp/glass fiber hybrid polypropylene composites are promising candidates for structural applications where high stiffness and thermal resistance is required. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2432–2441, 2007     

深潜壳体用高模量树脂基体的研究——基体模量对复合材料抗压抗剪性能的影响

制备了高模量树脂基单向复合材料，测试了单向复合材料的纵向压缩性能和平面剪切性能。研究了基体模量对单向复合材料抗压强度及复合材料平面剪切性能的影响，结果表明：单向复合材料的抗压强度与基体模量成线性比例关系，随基体模量的提高而提高，复合材料的平面剪切性能与基体模量基本上呈线性关系，平面剪切强度亦随基体模量的提高而提高。以模量达５．３６ＧＰａ的环氧树脂作为复合材料的树脂基体制备的，单向玻璃纤维增强复合材料其抗压强度高达１．２９５ＧＰａ，碳纤维增强的复合材料抗压强度高达１．３７２ＧＰａ，与普通环氧树脂的单向复合材料相比，分别提高了５５％和４５．８％；复合材料的平面剪切强度达６４．５ＭＰａ，比普通环氧树脂复合材料的平面剪切强度提高了４４．３％，满足了深潜壳体对复合材料抗压强度的要求。