Mechanical,thermal, and burning properties of viscose fabric composites: Influence of epoxy resin modification

The influence of epoxy resin modification by 3‐aminopropyltriethoxysilane (APTES) on various properties of warp knitted viscose fabric is reported in this study. Dynamic mechanical, impact resistance, flexural, thermal properties, and burning behavior of the epoxy/viscose fabric composites are studied with respect to varying content of silane coupling agent. The results obtained for APTES‐modified epoxy resin based composites reinforced with unmodified viscose fabric composites are compared to unmodified epoxy resin based composites reinforced with APTES‐modified viscose fabric. The dynamic mechanical behavior of the APTES‐modified resin based composites indicates improved interfacial adhesion. The composites prepared from modified epoxy resin exhibited a twofold increase in impact resistance. The improved adhesion between the fiber and modified resin was also visible from the scanning electron microscope analysis of the impact fracture surface. There was less influence of resin modification on the flexural properties of the composites. The 5% APTES modification induced early degradation of composites compared to all other composites. The burning rate of all the composites under study is rated to be satisfactory for use in automotive interior applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46673.     

CE/EP/CF复合材料的湿热性能研究

采用溶液预浸渍法分别制备了两种碳纤维(CF)增强环氧树脂(EP)改性氰酸酯树脂(CE)(CE/EP/CF)复合材料,研究了该复合材料的吸湿行为及湿热环境对其力学性能和微观结构的影响。结果表明,CE/EP基体具有比EP更小的吸湿能力;湿热环境对CE/EP/CF复合材料的纵向拉伸强度影响不大,但对其层间剪切强度的影响较为显著。     

Nanoclay and long-fiber-reinforced composites based on epoxy and phenolic resins

In this study, high-performance thermoset polymer composites are synthesized by using both long fibers and nanoclays. Epoxy and phenolic resins, the two most important thermoset polymers, are used as the polymer matrix. The hydrophobic epoxy resin is mixed with surface modified nanoclay, while the hydrophilic phenolic resin is mixed with unmodified raw nanoclay to form nanocomposites. Long carbon fibers are also added into the nanocomposites to produce hybrid composites. Mechanical and thermal properties of synthesized composites are compared with both long-fiber-reinforced composites and polymer- layered silicate composites. The optimal conditions of sample preparation and processing are also investigated to achieve the best properties of the hybrid composites. It is found that mechanical and thermal properties of epoxy and phenolic nanocomposites can be substantially improved. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of nano‐Ag particles and their modification on the mechanical and dielectric properties of epoxy resin

Nano‐Ag particles stabilized by a hyperbranched polymer (HBP) template were prepared for modifying the epoxy resin. The effects of preparation condition on the size and size distribution of Ag colloidal particles were studied. The Ag@HBP particles were then compounded with the epoxy resin to obtain the Ag@HBP/epoxy composites and the mechanical and dielectric properties of these composites were investigated. Dynamic mechanical analysis results show that the composites have higher loss factors than does the unmodified epoxy resin, which indicate better dissipation of mechanical energy and hence better shock or impact resistance. Fracture morphology of the composite shows a toughness feature. From the dielectric test results, the breakdown strength and dielectric constant of the composites at room temperature are increased, which can be explained by the Coulomb block effect. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Preparation and characterization of siliconized epoxy/bismaleimide (N,N′‐bismaleimido‐4,4′‐diphenyl methane) intercrosslinked matrices for engineering applications

Novel hybrid intercrosslinked networks of hydroxyl‐terminated polydimethylsiloxane‐modified epoxy and bismaleimide matrix systems have been developed. Epoxy systems modified with 5, 10, and 15 wt % of hydroxyl‐terminated polydimethylsiloxane (HTPDMS) were developed by using epoxy resin and hydroxyl‐terminated polydimethylsiloxane with γ‐aminopropyltriethoxysilane (γ‐APS) as compatibilizer and dibutyltindilaurate as catalyst. The reaction between hydroxyl‐terminated polydimethylsiloxane and epoxy resin was confirmed by IR spectral studies. The siliconized epoxy systems were further modified with 5, 10, and 15 wt % of bismaleimide (BMI). The matrices, in the form of castings, were characterized for their mechanical properties. Differential scanning calorimetry and thermogravimetric analysis of the matrix samples were also performed to determine the glass‐transition temperature and thermal‐degradation temperature of the systems. Data obtained from mechanical studies and thermal characterization indicate that the introduction of siloxane into epoxy improves the toughness and thermal stability of epoxy resin with reduction in strength and modulus values. Similarly the incorporation of bismaleimde into epoxy resin improved both tensile strength and thermal behavior of epoxy resin. However, the introduction of siloxane and bismaleimide into epoxy enhances both the mechanical and thermal properties according to their percentage content. Among the siliconized epoxy/bismaleimide intercrosslinked matrices, the epoxy matrix having 5% siloxane and 15% bismaleimide exhibited better mechanical and thermal properties than did matrices having other combinations. The resulting siliconized (5%) epoxy bismaleimide (15%) matrix can be used in the place of unmodified epoxy for the fabrication of aerospace and engineering composite components for better performance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 38–46, 2001     

Use of eco‐friendly epoxy resins from renewable resources as potential substitutes of petrochemical epoxy resins for ambient cured composites with flax reinforcements

In the last years, some high renewable content epoxy resins, derived from vegetable oils, have been developed at industrial level and are now commercially available; these can compete with petroleum‐based resins as thermoset matrices for composite materials. Nevertheless, due to the relatively high cost in comparison to petroleum‐based resins, their use is still restricted to applications with relatively low volume consumption such as model making, tuning components, nautical parts, special effects, outdoor sculptures, etc. in which, the use of composite laminates with carbon, aramid and, mainly, glass fibers is generalized by using hand layup and vacuum assisted resin transfer molding (VARTM) techniques due to low manufacturing costs and easy implementation. In this work, we study the behavior of two high renewable content epoxy resins derived from vegetable oils as potential substitutes of petroleum‐based epoxies in composite laminates with flax reinforcements by using the VARTM technique. The curing behavior of the different epoxy resins is compared in terms of the gel point and exothermicity profile by differential scanning calorimetry (DSC). In addition, overall performance of flax‐epoxy composites is compared with standardized mechanical (tensile, flexural and impact) and thermal (Vicat softening temperature, heat deflection temperature, thermo‐mechanical analysis) tests. The curing DSC profiles of the two eco‐friendly epoxy resins are similar to a conventional epoxy resin. They can be easily handled and processed by conventional VARTM process thus leading to composite laminates with flax with balanced mechanical and thermal properties, similar or even higher to a multipurpose epoxy resin. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Mechanical properties of carbon woven reinforced epoxy matrix composites. A study on the influence of matrix modification with polysulfone

An experimental investigation has been carried out to study the influence of thermoplastic addition on the mechanical properties of woven carbon fiber/epoxy matrix composites. As toughening agent bisphenol‐A polysulfone, PSu, has been added to the epoxy matrix. Flexural tests haved been performed to characterize the mechanical behavior of unmodified and PSu‐modified bulk tetra‐ and bifunctional epoxy matrices and also for the corresponding woven carbon fiber, CF, composite materials. Three‐point notched flexural tests been used to investigate the influence of polysulfone addition in the mode‐I fracture properties of the bulk epoxy matrices, relating them to their microstructural features investigated by atomic force microscopy (AFM). The double‐cantilever bea (DCB) and the end‐notched flexural (ENF) tests have been applied to characterize the interlaminar fracture toughness of the corresponding composites. For composites, the flexural properties were simmilar independent of the funcetionality of the epoxy matrix and of the thermoplastic content. Nevertheless, PSu addition to the epoxy matrix celarly enhanced the ode‐I and II interlaminar fracture toughness of the corresponding composites, the immprovement being higher for the composites manufactured with the bifunctional epoxy matrix at every thermoplastic content because of the lower crosslink density of the epoxy matrix.     

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     

Physico‐mechanical,thermal, and coating properties of composite materials prepared with epoxy resin/steel slag

The interest in using different solid waste as reinforcement in polymer composite preparation has increased considerably in recent years. Slag is one of the inorganic waste materials obtained from ore processing. In this work, epoxy composites filled with different percentages of slag were prepared. Physico‐mechanical, thermal, and coating properties of these composites were determined depending on the amount of filler, type of hardener, and polyethylene glycol (PEG) addition. X‐ray diffraction (XRD) studies were carried out to examine the compatibility of the filler and epoxy resin and XRD results showed good compatibility between two materials. The results of mechanical testing illustrated that hardness of the epoxy composites containing anhydride was partially higher than with Epamine PC17 in contrast to elongation at break. The tensile strength and Young modulus decreased with increasing filler amount. When compared to neat epoxy resin, corrosion, and adhesion properties of the composites with filler addition did not change significantly. The highest water sorption values were obtained for the epoxy composites with PEG addition. The composites hardened by anhydride had better thermal stability than the composites including Epamine PC17. POLYM. COMPOS., 38:1974–1981, 2017. © 2015 Society of Plastics Engineers     

Hygrothermal degradation of the composite laminates from woven carbon/SC‐15 epoxy resin and woven glass/SC‐15 epoxy resin

The degradation mechanism for hygrothermal aging of woven carbon‐epoxy and woven glass‐epoxy composite laminates was investigated in the micro‐scale. Interlaminar shear and cross laminar flexural tests were performed on notched and unnotched specimens to know the mechanical performance of the composite laminates. The Interlaminar Shear Stress (ISS) for both the composites was also evaluated and correlated with the number of hygrothermal cycles. Four‐point bending and tensile or compression shear loading configurations were also used. The stress at the onset of delamination (Delamination Damage Tolerance, DDT) was identified from the load‐deflection curve of the flexural specimens and correlated with the number of hygrothermal cycles. It was found that both the ISS and DDT decrease with the exposure time. Dimensional stability was almost unchanged throughout the aging process, although there was a very little moisture absorption (∼1.3%) in glass‐epoxy and carbon‐epoxy composite laminates. SEM photomicrographs of the delaminated surface show that failure occurs suddenly in a macroscopically brittle mode by crack initiation and propagation method. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers.     

FRP composites based on different types of glass fibers and matrix resins: A comparative study

Flexural properties, impact energy, heat deflection temperature, and resistance to thermal and hydrothermal degradation of composites based on E-glass and N-glass fibers as the reinforcing agents, and epoxy, unsaturated polyester, phenolic, and epoxy-phenolic resin systems as the matrix materials were studied and compared. As a reinforcing agent E-glass fiber is superior to N-glass fiber, particularly with respect to development of flexural strength and modulus, impact strength, and thermal resistance; N-glass fiber, however, imparts to the composites substantially higher resistance to hydrothermal degradation under boiling conditions in different chemical environments. For use of both E-glass and N-glass fibers as reinforcing agents, the general order of resistance to hydrothermal degradation for the composites based on different matrix resins is epoxy > phenolic > unsaturated polyester resin. Incorporation of a low dose of a rubbery polymer, such as styrene butadiene rubber (0.1–0.2%) and liquid polybutadiene (0.5–0.75%), in unsaturated polyester resin as the matrix resin measurably enhances impact energy of the composite. © 1995 John Wiley & Sons, Inc.     

Effects of hygrothermal aging on the thermomechanical properties of a carbon fiber reinforced epoxy sheet molding compound: An experimental research

Carbon fiber sheet molding compounds (C-SMCs) are discontinuous fiber reinforced composite materials. Among them, epoxy-based C-SMCs are becoming relevant materials due to their high thermomechanical performance and better formability than continuous fiber reinforced composites. The thermomechanical performance of epoxy resins and epoxy based continuous carbon fiber composites have shown to be influenced by hygrothermal aging. In this work, this influence is studied for an epoxy-based C-SMC. Epoxy-based C-SMC samples were hygrothermally aged by means of accelerated conditioning, exposing them to 65% relative humidity, and 80°C in a climatic chamber. The equilibrium moisture content, as well as the moisture diffusion coefficient has been determined. The thermomechanical properties of epoxy C-SMC have been analyzed by dynamic mechanical analysis, tensile, 3-point bending, and short beam tests in dry and aged samples. The results showed that epoxy C-SMC is affected by hygrothermal aging in the cases of moisture intake and its effects on T_g value, but interestingly, the hygrothermal aging did not generate any degradation effects in the mechanical response of epoxy C-SMC.     

Effect of organosilane coupling agents on microstructure and properties of nanosilica/epoxy composites

Three types of silane coupling agents, γ‐aminopropyltriethoxysilane, γ‐glycidoxypropyltrimethoxysilane, and γ‐methacryloxypropyltrimethoxysilane, were used as modifiers to modify the surface of the nanosilica, respectively, and the nanocomposites of the epoxy resin filled with nano‐sized silica modified by three silane coupling agents were prepared by physical blending. The properties of the modified silica nanoparticles were characterized by Fourier transform infrared spectrum and particle‐size analyzer. The microstructure, mechanical behavior, and heat resistant properties of the nanocomposites were investigated by transmission electron microscopy, scanning electron microscopy, thermo gravimetric analyses, differential thermal gravity, differential scanning calorimetry, and flexural tests. The results showed that these modifiers are combined to the surfaces of nanosilica by the covalent bonds, and they change the surface properties of nanosilica. The different structures of coupling agents have different effects on the dispersibility and stability of modified particles in the epoxy matrix. In comparison, the silica nanoparticles modified by γ‐glycidoxypropyltrimethoxysilane exhibit a good dispersivity. The nanocomposites with 4 wt% weight fraction nanosilica modified by γ‐glycidoxypropyltrimethoxysilane have higher thermal decomposing temperature and glass transition temperature than those of the other two composites with the same nanosilica contents, and they are raised by 43.8 and 8°C relative to the unmodified composites, respectively. The modified silica nanoparticles have good reinforcing and toughening effect on the epoxy matrix. The ultimate flexural strengths of the composites with 4 wt% nanoparticles modified by γ‐aminopropyltriethoxysilane, γ‐glycidoxypropyltrimethoxysilane, and γ‐methacryloxypropyltrimethoxysilane are increased by 10, 30, and 8% relative to the unmodified composites, respectively. The flexural fracture surfaces of modified composites present ductile fracture features. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers     

某高导热纤维及其复合材料性能研究

研究了某高导热纤维/环氧树脂单向层复合材料的导热系数和力学性能,发现某高导热纤维/环氧树脂单向层复合材料导热性能提高的同时其个别复合材料性能降低;分析认为某高导热纤维与环氧树脂的界面性能是影响复合材料力学性能的重要因素,同时研究了某高导热纤维的表面微观形貌和表面化学特性、结晶度及某高导热纤维/环氧树脂浸胶丝束的力学性能...     

玻璃纤维／环氧树脂复合材料的热性能

本文采用E-玻璃纤维作为增强材料、双酚A环氧树脂和芳胺类固化剂作为基体制成复合材料试样,利用动态与静态热分析方法测定玻璃纤维／环氧树脂基复合材料的热性能,研究了玻璃纤维含量对复合材料动态热机械性能、玻璃化温度等热性能的影响。     

Study of jute fiber reinforced polyester composites by dynamic mechanical analysis

Cyanoethylation of jute fibers in the form of nonwoven fabric was studied, and these chemically modified fibers were used to make jute–polyester composites. The dynamic mechanical thermal properties of unsaturated polyester resin (cured) and composites of unmodified and chemically modified jute–polyester were studied by using a dynamic mechanical analyzer over a wide temperature range. The data suggest that the storage modulus and thermal transition temperature of the composites increased enormously due to cyanoethylation of fiber. An increase of the storage modulus of composites, prepared from chemically modified fiber, indicates its higher stiffness as compared to a composite prepared from unmodified fiber. It is also observed that incorporation of jute fiber (both unmodified and modified) with the unsaturated resin reduced the tan δ peak height remarkably. Composites prepared from cyanoethylated jute show better creep resistance at comparatively lower temperatures. On the contrary, a reversed phenomenon is observed at higher temperatures (120°C and above). Scanning electron micrographs of tensile fracture surfaces of unmodified and modified jute–polyester composites clearly demonstrate better fiber–matrix bonding in the case of the latter. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1505–1513, 1999     

纳米Sb_2O_3/环氧复合材料阻燃耐热及力学性能研究

通过氧指数、力学性能测定及热重分析研究了纳米Sb2O3与十溴二苯醚(FR-10)配合使用时,纳米Sb2O3/环氧树脂复合材料的阻燃性、耐热性和力学性能,并与微米Sb2O3/环氧树脂体系进行了对比。结果表明,Sb2O3与FR-10共用时对环氧树脂具有明显的协同阻燃作用,Sb2O3的加入抑制了环氧树脂固化物的热分解;添加少量的Sb2O3就能达到较好的阻燃效果。加入纳米Sb2O3后材料的拉伸强度、弯曲强度和冲击强度均有提高。添加纳米级Sb2O3时体系阻燃、耐热和力学性能明显好于微米级Sb2O3填充体系。     

Preparation and properties of nano‐Al2O3 particles/polyester/epoxy resin ternary composites

This article presents the results of an experimental study on the preparation and properties of new ternary composites composed of nano‐Al₂O₃ particles, polyester, and epoxy resin. The ternary composites were prepared by the addition of the nano‐Al₂O₃ particles in a binary matrix, with elevated viscosity, of the epoxy resin modified by the polyester. The nano‐Al₂O₃ particles were previously located and dispersed in the polyester phase. The study showed that the ternary system was a type of nanoscale dispersed composite with high strength and toughness as well as modulus, combined with excellent dielectric and heat‐resistance properties. All related properties of the composites were remarkably superior to those of both the binary matrix and the unmodified epoxy resin. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 70–77, 2002     

Unmodified and Modified Surface Sisal Fibers as Reinforcement of Phenolic and Lignophenolic Matrices Composites: Thermal Analyses of Fibers and Composites

Summary: The study and development of polymeric composite materials, especially using lignocellulosic fibers, have received increasing attention. This is interesting from the environmental and economical viewpoints as lignocellulosic fibers are obtained from renewable resources. This work aims to contribute to reduce the dependency on materials from nonrenewable sources, by utilizing natural fibers (sisal) as reinforcing agents and lignin (a polyphenolic macromolecule obtained from lignocellulosic materials) to partially substitute phenol in a phenol‐formaldehyde resin. Besides, it was intended to evaluate how modifications applied on sisal fibers influence their properties and those of the composites reinforced with them, mainly thermal properties. Sisal fibers were modified by either (i) mercerization (NaOH 10%), (ii) esterification (succinic anhydride), or (iii) ionized air treatment (discharge current of 5 mA). Composites were made by mould compression, of various sisal fibers in combination with either phenol‐formaldehyde or lignin‐phenol‐formaldehyde resins. Sisal fibers and composites were characterized by thermogravimetry (TG) and DSC to establish their thermal stability. Scanning electron microscopy (SEM) was used to investigate the morphology of unmodified and modified surface sisal fibers as well as the fractured composites surface. Dynamic mechanical thermoanalysis (DMTA) was used to examine the influence of temperature on the composite mechanical properties. The results obtained for sisal fiber‐reinforced phenolic and lignophenolic composites showed that the use of lignin as a partial substitute of phenol in phenolic resins in applications different from the traditional ones, as for instance in other than adhesives is feasible.

Micrograph of the impact fracture surface of phenolic composite reinforced with mercerized sisal fiber (500 X).     

Dispersion,Mechanical and Thermal Properties of Epoxy Resin Composites Filled with the Nanometer Carbon Black

The nanometer carbon black (CB) was employed to prepare epoxy resin/carbon black (EP/CB) composites by blending-casting method. The different modified methods of silicone coupling agent were used to improve the dispersion of CB in epoxy resin. The mechanical and thermal properties of EP/CB composites were investigated. Experimental results showed that the mechanical properties increased at first, but decreased with excessive addition of CB. When the mass fraction of CB was 2%, the mechanical properties were maximum. The use of modified CB significantly enhanced the mechanical properties of the composites. For given CB loading, the CB modified by pretreatment method displayed better dispersion in the epoxy resin than that of the direct mixing method. SEM observation revealed that the tensile fracture surface of the composite filled with 2 wt% modified CB held more microcracks than that of 5 wt% modified CB, and the formed microcracks could consume more energy of rupture, finally to have better tensile strength. DSC analysis showed that the glass transition temperature (Tg) of the composites increased with the increasing mass fraction of CB.