Three‐body abrasive wear behavior of E‐glass fabric reinforced/graphite‐filled epoxy composites

The present article summarizes an experimental study on three‐body abrasive wear behavior of glass fabric reinforced/graphite particulate‐filled epoxy composites. The wear behavior was assessed by rubber wheel abrasion tests (RWAT). The angular silica sand particle sizes in the range 200–250 μm were used as dry and loose abrasives. The tests were carried out for 270, 540, 810, and 1,080 m abrading distances at 22 and 32 N loads. The worn surfaces were examined using scanning electron microscopy (SEM). The results showed varied responses under different abrading distance due to the addition of glass fabric/graphite filler into neat epoxy. It was observed that the glass fabric reinforcement to epoxy matrix (G‐E) is not beneficial to abrasive wear resistance. Further, inclusion of graphite filler to glass fabric reinforced epoxy composite performed poorly resulting in significant deterioration in wear performance while the neat epoxy showed better wear performance. Selected mechanical properties such as hardness, ultimate tensile strength, and elongation at fracture were analyzed for investigating wear property correlations. The worn surface features were studied using SEM to give insight into the wear mechanisms. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Fabrication and characterization of functionally graded nanoclay/glass fiber/epoxy hybrid nanocomposite laminates

In this work, hardness, tensile, impact, bearing strength and water absorption tests were performed to study the mechanical properties of stepwise graded and non-graded hybrid nanocomposites. Three different stepwise graded nanocomposites and one non-graded (homogeneous) nanocomposite with the same geometry and total nanoclay content of 10 wt% were designed and prepared. Moreover, one neat glass fiber laminate was manufactured. The results of the tests indicated that addition of the graded and non-graded nanoclay improves hardness over neat glass fiber reinforcement. The maximum increase in hardness of about 53% over neat specimen is obtained for specimens that have the highest weight percentage (2 wt%) of the clay nanoparticles on its surface (S-specimen and the side of F-specimen that reinforced with 2 wt% nanoclay). The gradation process results in an increase in hardness of about 11% compared with non-graded (homogeneous) specimen. In addition, an improvement of 11.9% in strain-to-failure is achieved with specimen having greatest amount of nanoclay in the middle over neat glass fiber/epoxy composite. The other nanoclay-filled glass fiber composites have strain-to-failure close to neat glass fiber/epoxy. The addition of nanoclay reinforcement has insignificant effect on ultimate tensile strength, tensile modulus, water absorption, bearing strength and impact strength compared with neat glass fiber/epoxy.     

Epoxy/alumina nanoparticle composites. II. Influence of silane coupling agent treatment on mechanical performance and wear resistance

Two silane coupling agents (SCAs) were used to treat alumina nanoparticles to improve nanoparticle dispersion into the polymer matrix. [3‐(2‐Aminoethylamino)‐propyl]‐trimethoxysilane [a reactive silane coupling agent (RSCA)] was able to form covalent bonds with both the reinforcing agent (alumina nanoparticles) and the epoxy matrix, whereas 3‐(trimethoxysilyl) propyl methacrylate (a nonreactive SCA) could not covalently interact with the epoxy resin. The strengthening of the filler–matrix interactions by means of covalent bonds resulted in improved flexural strength, strain, and especially, wear resistance. The wear rate and the weight loss of the RSCA‐treated alumina nanoparticle composite were the best among the investigated composite samples and equal to these of the neat epoxy matrix. This improvement was due to better nanoparticle dispersion, a result of the SCA treatment of the alumina nanoparticles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4410–4417, 2006     

Mechanical properties of hybrid structural composites reinforced with nanosilica

Epoxy‐based hybrid structural composites reinforced with 14 nm spherical silica particles were investigated for mechanical properties as a function of nanosilica loading fractions. Composites were fabricated using continuous glass or carbon fiber of unidirectional architecture and nanosilica dispersed epoxy, through resin film infusion process. Uniform dispersion of nanoparticles in resin matrix was ensured by an optimized ultrasound‐assisted process. Although resin viscosity marginally reduces in the presence of nanosilica enabling a better control in composite manufacturing process, glass transition temperature of epoxy remained unaffected at low weight fractions. Compressive strength of hybrid glass or carbon fiber/epoxy composites showed more than 30–35% increase with nanosilica at a concentration as low as 0.2 wt%. Tensile and compressive properties of hybrid composites in transverse direction to the reinforcement remained unaffected. POLYM. COMPOS. 37:1216–1222, 2016. © 2014 Society of Plastics Engineers     

Surface‐modified silica nanoparticles for reinforcement of PMMA

Polymethyl methacrylate (PMMA) was introduced onto the surface of silica nanoparticles by particle pretreatment using silane coupling agent (γ‐methacryloxypropyl trimethoxy silane, KH570) followed by solution polymerization. The modified silica nanoparticles were characterized by Fourier‐transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Sedimentation tests and lipophilic degree (LD) measurements were also performed to observe the compatibility between the modified silica nanoparticles and organic solvents. Thereafter, the PMMA slices reinforced by silica‐nanoparticle were prepared by in situ bulk polymerization using modified silica nanoparticles accompanied with an initiator. The resultant polymers were characterized by UV–vis, Sclerometer, differential scanning calorimetry (DSC). The mechanical properties of the hybrid materials were measured. The results showed that the glass transition temperature, surface hardness, flexural strength as well as impact strength of the silica‐nanoparticle reinforced PMMA slices were improved. Moreover, the tensile properties of PMMA films doped with silica nanoparticles via solution blending were enhanced. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

A Study on Polyurethane Hybrid Nanocomposite Foams Reinforced with Multiwalled Carbon Nanotubes and Silica Nanoparticles

Multifunctional polyurethane foams reinforced with multiwalled carbon nanotubes and silica nanoparticles enhanced specific properties. We studied the effects of nanoparticle addition into polyurethane on mechanical properties and thermal stability by means of tensile, Charpy impact, hardness tests, and thermogravimetric analysis. Nanoparticles added to polyurethane are multiwalled carbon nanotubes, two types of silica nanoparticles, and multiwalled carbon nanotube/spherical silica as hybrid filler. Hybrid polyurethane/spherical silica/multiwalled carbon nanotube nanocomposite with the constant overall content of 0.75?wt% showed higher tensile strength, hardness, and thermal stability than either of nanoparticles at this content, which approves a synergistic effect between multiwalled carbon nanotubes and silica nanoparticles.     

Nanoparticle dispersed resins and composites under quasi‐static loading: Shear plugging behavior

Experimental studies are presented on the quasi‐static shear plugging behavior of nanoparticle dispersed materials viz symmetric balanced cross‐ply laminates made using unidirectional E‐glass fabric with epoxy resin, and neat epoxy resin. The nanoparticles used are nanosilica and multiwalled carbon nanotube for E‐glass/epoxy and nanosilica for epoxy resin. The effect of nanoparticle dispersion on shear plugging strength was evaluated. Shear plugging strength was enhanced up to 10.5% for E‐glass/epoxy and up to 17.0% for neat epoxy resin on addition of nanoparticles. Shear plugging strength of nanoparticle dispersed composites decreased with an increase in specimen thickness. POLYM. COMPOS., 37:3411–3415, 2016. © 2015 Society of Plastics Engineers     

The effect of silica nanoparticles and carbon nanotubes on the toughness of a thermosetting epoxy polymer

Silica nanoparticles and multiwalled carbon nanotubes (MWCNTs) have been incorporated into an anhydride‐cured epoxy resin to form “hybrid” nanocomposites. A good dispersion of the silica nanoparticles was found to occur, even at relatively high concentrations of the nanoparticles. However, in contrast, the MWCNTs were not so well dispersed but relatively agglomerated. The glass transition temperature of the epoxy polymer was 145°C and was not significantly affected by the addition of the silica nanoparticles or the MWCNTs. The Young's modulus was increased by the addition of the silica nanoparticles, but the addition of up to 0.18 wt % MWCNTs had no further significant effect. The addition of both MWCNTs and silica nanoparticles led to a significant improvement in the fracture toughness of these polymeric nanocomposites. For example, the fracture toughness was increased from 0.69 MPam^1/2 for the unmodified epoxy polymer to 1.03 MPam^1/2 for the hybrid nanocomposite containing both 0.18 wt % MWCNTs and 6.0 wt % silica nanoparticles; the fracture energy was also increased from 133 to 204 J/m². The mechanisms responsible for the enhancements in the measured toughness were identified by observing the fracture surfaces using field‐emission gun scanning electron microscopy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The effect of nanosilica on mechanical,thermal and morphological properties of epoxy coating

In this study, nanosilica of very high specific surface area is used as reinforcing filler for preparing an epoxy-based nanocomposite coating. For appropriate dispersion of nanoparticles in the polymer matrix, ultrasound waves were applied after mechanical mixing. The resulting perfect dispersion of nanosilica particles in epoxy coating revealed by transmission electron microscopy ensured the transparency of the nanocomposite. Nanoindentation was used to determine some mechanical properties such as hardness and elastic modulus. The obtained results show 26 and 21% increases in hardness and elastic modulus, respectively for resin filled with 5% nanosilica compared to neat epoxy. DMA results show that the glass transition temperature of samples is increased with increasing silica nanoparticles. The result of TGA shows significant improvement of the thermal decomposition temperature of epoxy coating containing 5% nanosilica compared to neat epoxy. Scanning electron microscopy (SEM) micrographs of fractured surfaces show increased roughness with nanosilica addition.     

炭黑、微珠粉填充PE-UHMW复合材料性能比较分析

对超高相对分子质量聚乙烯(PE-UHMW)和炭黑、微珠粉填充的PE-UHMW复合材料进行了拉伸、硬度和磨损性能试验。结果表明：炭黑、微珠粉对PE-UHMW拉伸性能和摩擦磨损性能的影响不同，两种填充材料加入PE-UHMW后，复合材料的拉伸强度和断裂延伸率有不同程度的下降。炭黑的加入会使PE-UHMW的硬度下降，但可较好地改善其耐磨性，而微珠粉的加入会使PE-UHMW的耐磨性下降。     

Viscoelasticity of epoxy resin/silica hybrid materials with an acid anhydride curing agent

The viscoelasticity of epoxy resin/silica hybrid materials manufactured by the sol–gel process with an acid anhydride curing agent was investigated in terms of morphology. Transmission microscopy observations demonstrated that all the prepared hybrid samples had a two‐phased structure consisting of an epoxy phase and a silica phase. The formed silica had either nanosized particles or coarse domains, depending on the catalyst for the sol–gel process. Raman spectroscopy analysis showed that the formed silica had features typical of sol–gel derived silica glass and that the ring‐opening reactions of the epoxy groups developed in the hybrid samples and in the neat epoxy samples. In dynamic mechanical thermal analysis, there were two transition temperatures due to epoxy chain mobility and epoxy network relaxation, through which the moduli changed by nearly 3 orders of magnitude. The hybridization disturbed epoxy network formation but also reinforced the epoxy network with the formed silica, which was characterized by the activation energy of the network relaxation; therefore, the modulus of the rubbery state was correlated to the activation energy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

SSBR和ESBR胎面胶性能研究

研究炭黑或白炭黑补强溶聚丁苯橡胶(SSBR)和乳聚丁苯橡胶(ESBR)胎面胶的性能.结果表明,SSBR与白炭黑的界面作用强于ESBR;当采用白炭黑补强时,SSBR硫化胶的物理性能优于ESBR,而采用炭黑补强时,SSBR硫化胶的物理性能无明显优势;与炭黑补强SBR硫化胶相比,白炭黑补强SBR硫化胶的抗湿滑性能较好,滚动阻力较低,但耐磨性能较差,其中白炭黑补强SSBR硫化胶的抗湿滑性能最突出.     

Development and high stress abrasive wear behavior of milled carbon fiber‐reinforced epoxy gradient composites

Milled carbon fiber‐reinforced polysulfide‐modified epoxy gradient composites have been developed. Density and hardness increases with the increase of carbon fiber content in the direction of centrifugal force, which shows the formation of gradient structure in the composite. High stress abrasive wear test was conducted on the gradient composites by using a Suga Abrasion Wear Tester. Abrasive wear rate reduced on increase of milled carbon fiber content from 0.15 to 1.66 vol%. Reduction in abrasive wear rate in milled carbon fiber‐reinforced epoxy gradient composites has been attributed to the increase of hardness, presence of random milled fibers, and debris of composite materials, which gave resistance and reduced wear rate. There is a small decrease in specific wear rate on adding 0.15 vol% milled carbon fibers. Further decrease of specific wear rate is observed on adding 0.45 vol% milled carbon fibers. After 3 N load, there is a decrease in specific wear rate behavior on adding 0.45 vol% carbon fibers, which further decreases on adding 0.60 vol% of carbon fibers. There is a remarkable decrease in specific wear rate up to 5 N load for 1.66 vol% milled carbon fiber‐reinforced composite. Reduction in specific wear rate on adding milled carbon fibers is based on the formation of debris, which remained intact in their respective positions due to the interfacial adhesion between milled carbon fibers and epoxy resin. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Facile synthesis of biosourced graphitic nanoparticle anchored silica nanoparticle hybrid for the development of functional polyurethane composite

The present work demonstrates a facile approach for the generation of functional polyurethane coatings using a biosourced graphitic nanoparticle anchored silica nanoparticle hybrid. Hence, 3-aminopropyl triethoxysilane was reacted with silica nanoparticles to obtain amino groups on the surface and was further reacted with a carboxyl terminated graphitic nanoparticle obtained from the incineration of camphor. The formation of hybrid structure was established through the electron microscopy images and other spectroscopic techniques. The infrared spectroscopic measurements reveal the successful formation of carbon–silica nanohybrid through amide linkages. The synthesized hybrids were dispersed in different weight percentages into a polyether polyol and then reacted with diisocyanate to form polyurethane nanocomposite. The presence of unreacted amino groups in the carbon–silica nanohybrid is helpful in urea linkage formation, which leads to uniform dispersion in the polymer matrix. The prepared polyurethane composite possess exceptional physico-chemical properties owing to the presence of nanoparticulates. Interestingly, the resulting composite showed shape recovery behavior. The shape recovery behavior of the obtained coating under temperature of 60 °C was found to correlate with the increase in the nanomaterial content. It is also found that storage modulus of the composite at room temperature increases from 183 MPa to 432 MPa in the case of neat and 1.5% carbon-silica nanohybrid incorporated polyurethane respectively.     

Effect of silica nanoparticle size on toughening mechanisms of filled epoxy

The addition of silica nanoparticles (23 nm, 74 nm, and 170 nm) to a lightly crosslinked, model epoxy resin, was studied. The effect of silica nanoparticle content and particle size on glass transition temperature (T_g), coefficient of thermal expansion (CTE), Young's modulus (E), yield stress (σ), fracture energy (G_IC) and fracture toughness (K_IC), were investigated. The toughening mechanisms were determined using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and transmission optical microscopy (TOM). The experimental results revealed that the addition of silica nanoparticles did not have a significant effect on T_g or the yield stress of epoxy resin, i.e. the yield stress and T_g remained constant regardless of silica nanoparticle size. As expected, the addition of silica nanoparticles had a significant impact on CTE, modulus and fracture toughness. The CTE values of nanosilica-filled epoxies were found to decrease with increasing silica nanoparticle content, which can be attributed to the much lower CTE of the silica nanoparticles. Interestingly, the decreases in CTE showed strong particle size dependence. The Young's modulus was also found to significantly improve with addition of silica nanoparticles and increase with increasing filler content. However, the particle size did not exhibit any effect on the Young's modulus. Finally, the fracture toughness and fracture energy showed significant improvements with the addition of silica nanoparticles, and increased with increasing filler content. The effect of particle size on fracture toughness was negligible. Observation of the fracture surfaces using SEM and TOM showed evidence of debonding of silica nanoparticles, matrix void growth, and matrix shear banding, which are credited for the increases in toughness for nanosilica-filled epoxy systems. Shear banding mechanism was the dominant mechanism while the particle debonding and plastic void growth were the minor mechanisms.     

Microhardness of carbon fiber reinforced epoxy and thermoplastic polyimide composites

We have examined the micro indentation hardness of a series of carbon fiber reinforced epoxy and thermoplastic polyimide (TPI) composites. In the epoxy systems, the influence of Nylon particles was studied. The effect of crystallization of the thermoplastic polyimide upon the microhardness values of the resin was also investigated. The microstructure of the TPI-composites was characterized by X-ray diffraction. The results show that the addition of carbon fibers to the neat resins greatly increases the microhardness and thus the yield stress of the composite. The value of the microhardness technique is highlighted in emphasizing the heterogeneity of the CFRC.     

UV-waterborne polyurethane-acrylate nanocomposite coatings containing alumina and silica nanoparticles for wood: mechanical, optical, and thermal properties assessment

The effect of alumina and silica nanoparticles on mechanical, optical, and thermal properties of UV-waterborne nanocomposite coatings was investigated. The addition of nanoalumina and nanosilica was shown to decrease the hardness because of nanoparticle aggregation. In comparison to the neat coating and despite the presence of aggregates, the scratch resistance of nanocomposite coatings was significantly improved. As expected, the gloss of UV-waterborne coatings was reduced following the addition of nanoparticles due to an increase of the surface roughness. Alumina and silica nanoparticles were found to enhance the glass transition temperature of PUA nanocomposite coatings by hindering the mobility of macromolecular chains at the interface around the nanoparticles. Finally, the interest and efficiency of grafting trialkoxysilanes was demonstrated with the study of nanosilica behavior. Not only was the dispersion of nanosilica enhanced following trialkoxysilanes grafting onto silica nanoparticles, but also the scratch resistance and the adhesion of UV-waterborne coatings containing nanosilica markedly increased even with 1 wt% content. Silica which is recommended in the wooden furniture and kitchen cabinet manufacturing industry as nano-reinforcement provides improved properties well suited in surface coating applications to efficiently protect surface of wood substrates.     

纤维增强环氧树脂基复合材料的研究进展

综述了纤维增强环氧树脂基复合材料的应用及研究进展,其中包括玻璃纤维(GF)增强、碳纤维(CF)增强,芳纶纤维,混杂纤维及植物纤维增强等。     

Adhesion Characteristics of Carbon Black Embedded Glass/Epoxy Composite

The surface of glass/epoxy composite material was embedded with carbon black which was dispersed in methyl ethyl ketone (MEK) during the curing process to enhance the adhesion strength of the glass/epoxy composite structure. The morphological effect of the carbon black on the surface of composite was observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Quantitative chemical bonding analysis with X-ray photoelectron spectroscopy (XPS) was also performed to observe chemical bonding states on the surface. The lap shear strength of the glass/epoxy composite adhesive joints where composite adherends were embedded with carbon black was investigated with respect to the type and amount of embedment. Also, the tensile properties of the carbon black embedded glass/epoxy composites were measured to observe the mechanical degradation of the composite due to the MEK. The surface free energies of carbon black embedded composites were determined from the van Oss–Chaudhury–Good equation to correlate the lap shear strength of the adhesive joints with the surface free energies of composite adherends. From the experimental results, it was found that the carbon black embedment of the composite adherend improved much the bond strength due to the increased surface roughness on nano-scale as well as increased surface free energy.     

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.