Effect of Halloysite Nanotube Incorporation in Epoxy Resin and Carbon Fiber Ethylene/Ammonia Plasma Treatment on Their Interfacial Property

Abstract

Effects of halloysite nanotube (HNT) loading of up to 2% in epoxy resin on its mechanical properties were characterized. The interfacial property of the resin with carbon fiber nanocomposite was also studied. Single fiber composite (SFC) technique was used to characterize the carbon fiber/epoxy resin interfacial shear stress. Carbon fibers were also coated with ammonia/ethylene plasma polymer to obtain a thin coating of the polymer with amine groups that could react with the epoxy and thus improve the interfacial property. The results indicated that the Young’s modulus of HNT containing nanocomposites increased slightly up to a loading of 0.25% after which it started to decrease. The tensile strength, however, steadily decreased with increasing of HNT loading although the fracture strain did not change significantly. This might be related to the nanotube shape, size and clustering. The interfacial shear strength (IFSS) was also increased slightly with HNT loading. The ethylene/ammonia plasma polymer coated fibers exhibited significantly higher IFSS by over 150%, independent of the HNT loading. The highest IFSS obtained was almost 79 MPa for plasma treated fibers. The results suggest that the carbon fiber/epoxy interface is not affected by the incorporation of up to 1.5% of HNT. Furthermore, the fiber surface modification through plasma polymerization is an effective method to improve and control the IFSS.     

Fabrication of hybrid matrix/silane modified carbon fabric composites and study of their mechanical properties

Carbon fiber reinforced polymer composites are an extremely strong and light fiber-reinforced plastics that contains carbon fiber. In the present study, carbon fabrics were treated with various weight percentages of silane and were confirmed by spectral analysis (Fourier transform infrared). The treated carbon fibers were reinforced in hybrid resin (a combination of vinyl ester and epoxy at a ratio of 80:20) by using vacuum-assisted resin transfer mold technique. The composites were tested to know their tensile strength, modulus, flexural strength, modulus, and interlaminar shear strength. The hybrid matrix specimen was also prepared and tested for the mechanical properties and confirmed the miscibility by differential scanning calorimetry and X-ray diffraction. The mechanical properties of hybrid matrix composites (HMCs) were studied by fracture surface morphology with scanning electron microscope. The mechanical properties of the HMCs increased with silane treatment. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47695.     

The effect of silica (SiO2) nanoparticles and ammonia/ethylene plasma treatment on the interfacial and mechanical properties of carbon-fiber-reinforced epoxy composites

A nanoparticle dispersion is known to enhance the mechanical properties of a variety of polymers and resins. In this work, the effects of silica (SiO₂) nanoparticle loading (0–2 wt%) and ammonia/ethylene plasma-treated fibers on the interfacial and mechanical properties of carbon fiber–epoxy composites were characterized. Single fiber composite (SFC) tests were performed to determine the fiber/resin interfacial shear strength (IFSS). Tensile tests on pure epoxy resin specimens were also performed to quantify mechanical property changes with silica content. The results indicated that up to 2% SiO₂ nanoparticle loading had only a little effect on the mechanical properties. For untreated fibers, the IFSS was comparable for all epoxy resins. With ethylene/ammonia plasma treated fibers, specimens exhibited a substantial increase in IFSS by 2 to 3 times, independent of SiO₂ loading. The highest IFSS value obtained was 146 MPa for plasma-treated fibers. Interaction between the fiber sizing and plasma treatment may be a critical factor in this IFSS increase. The results suggest that the fiber/epoxy interface is not affected by the incorporation of up to 2% SiO₂ nanoparticles. Furthermore, the fiber surface modification through plasma treatment is an effective method to improve and control adhesion between fiber and resin.     

Interaction between the reinforcement and matrix in carbon-fiber-reinforced composite: Effect of forming the thin layer of polyimide resin on carbon fiber by in situ polymerization

For the purpose of enhancing the reinforcement–matrix interaction in carbon-fiber-reinforced polymer composite, mechanical and spectroscopic studies were made on the epoxy resin composite reinforced with the carbon fiber coated with thin Layer of polyimide resin. On the loss modulus and loss tangent vs. temperature curves, a subtransition appears at a temperature above the primary transition. The T-peel strength of a laminated specimen and the fiber efficiency factors for modulus and strength are larger than those of the composite reinforced with nonpolyimide treated fiber. These results show the increased interaction between the epoxy resin and the carbon fiber coated with polyimide resin. The occurrence of specific interaction between an epoxy resin and the polyimide resin are recognized on fourier transform infrared spectra.     

Effect of cyclic moisture absorption desorption on the mechanical properties of silanized jute-epoxy composites

The goal of this paper is to discuss the influence of water absorption-desorption cycles on the mechanical properties of natural fiber reinforced plastics. Therefore, epoxy resins with jute wovens as reinforcement with untreated and silane treated fibers were investigated. Silane treatment of fibers led to increased tensile, flexural strength, and Young's modulus of composites with up to 30%. Absorption-desorption cycles of fibers changed the fracture mechanisms of fibers without having significant effects on the tensile strength of the fibers. Light microscopic investigations showed that absorption-desorption cycles of composites led to the debonding of resin from fibers as well as to cracks in the adjacent resin. Because of these mechanisms, tensile strength and Young's modulus decrease, independent of the quality of fiber resin adhesion. For dynamic loadings, storage cycle induces damages, further bringing about a decreased dynamic modulus and an increased progress in damage with increasing load cycles during the first two environmental cycles, being constant afterwards.     

Pseudoreinforcement effect of multiwalled carbon nanotubes in epoxy matrix composites

The carbon nanotube possesses outstanding physical properties. Theoretically, adding carbon nanotubes into a polymer matrix can remarkably improve the mechanical properties of the polymer matrix. In the present work, a series of composites was prepared by incorporating multiwalled carbon nanotubes (MWNTs) into an epoxy resin. The influences of MWNT content and curing temperature on the flexural properties of the epoxy resin were investigated. The results showed that a very low MWNT content should be used to ensure homogeneous dispersion of MWNTs in the epoxy matrix. A higher MWNT content may lead to deteriorated mechanical properties of the composites because of the aggregation of MWNTs. A decline in the flexural properties of the neat epoxy resin with increasing curing temperature was found. However, under the same curing conditions, improvement in flexural properties was observed for the composite with the low MWNT content and a mild curing temperature. The improvement was far beyond the predictions of the traditional short‐fiber composite theory. In fact, this improvement should be attributed to the retarding effect of MWNTs on the curing reaction of epoxy matrix. Therefore, the improvement in the flexural properties was only a pseudoreinforcement effect, not a nano‐reinforcement effect of the MWNTs on the epoxy resin. Perhaps, it is better for MWNTs to be used as functional fillers, such as electrical or thermal conductive fillers, than as reinforcements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3664–3672, 2006     

淀粉纳米晶对玻璃纤维的表面改性研究

采用自制的淀粉纳米晶(SNC)对玻璃纤维进行表面处理,增加其与环氧树脂基体的界面剪切强度(IFSS)。研究了处理方式、处理时间、SNC乙醇分散液浓度、热处理温度等工艺参数对SNC在玻璃纤维表面沉积情况的影响,以及对改性玻璃纤维与环氧树脂的界面性能的影响规律。采用扫描电子显微镜、单纤维强力仪对处理前后玻璃纤维进行表征,并采用微脱粘法测试玻璃纤维与环氧树脂的界面粘结情况。结果表明,当重力静置处理时间24 h,SNC乙醇分散液浓度为1 g/100 m L时,SNC在玻璃纤维表面均匀沉积,且能显著提高玻璃纤维与环氧树脂的IFSS,为27.29 MPa,较未处理的纤维增加29.3%。150℃热处理4 h后,X射线光电子能谱结果显示SNC与玻璃纤维形成化学键合,进一步增加纤维与环氧树脂的界面粘结,IFSS值达到32.30 MPa,较未处理的纤维增加53%,且纤维的拉伸强度得到较好的维持。     

Characterization of the interphase in carbon fiber/polymer composites using a nanoscale dynamic mechanical imaging technique

The interphase of fiber reinforced polymer composites is a narrow region around the fiber, and the mechanical performance of a composite strongly depends on the properties of the interphase. The interphase of carbon fiber reinforced polymer composites (CFRPs) is difficult to quantitatively characterize because of its nanometer dimension. To solve this problem, we present a nanomechanical imaging technique for mapping the dynamic mechanical property around the interphase region in CFRPs, and for providing nanoscale information of the interfacial dimension. The experimental results show that this method can determine the width and topography of the interphase with nanoscale lateral resolution, based on the storage modulus profile on the cross section of the composite. The average interphase thicknesses of a T300 carbon fiber/epoxy resin composite and a T700 carbon fiber/bismaleimide resin composite are 118 nm and 163 nm, respectively, and the size of interphase is uneven in width and “river-like”, which is consistent with the surface topography of the carbon fibers. Furthermore, the effect of water-aging on the interphase of the T300/epoxy composite was analyzed using the in situ imaging technique. An increase in the interphase width and interface debonding were revealed, implying a degradation in the interphase region.     

基于NOL环的高性能纤维与环氧树脂的匹配性研究

纤维与树脂的界面对复合材料的整体力学性能有着显著的影响。基于NOL环的宏观力学测试一般被用来反映复合材料的界面粘结性能,因此适用于评价纤维与树脂之间的宏观力学性能匹配性。为了探究高性能碳纤维T700SC、T800HB及高强玻璃纤维与环氧树脂的宏观力学性能匹配性,本研究首先根据GB/T 1458—2008国家标准制备NOL环试样,再借助NOL环的拉伸和层间剪切强度测试分析了高性能纤维与环氧树脂不同匹配组合宏观力学性能差异的原因,并寻找出最佳匹配组合。结果表明:玻璃纤维与环氧树脂的界面存在最佳的粘结强度,而且不同粘结强度导致拉伸强度和破坏机理不同,而碳纤维复合材料界面性能较差,容易分层破坏;T800HB与环氧树脂的宏观力学匹配性优于T700SC,环氧树脂力学性能、碳纤维的表面微观结构与性质以及环氧树脂与碳纤维之间的相互作用关系是影响界面粘结性能的根本原因。该研究在高性能纤维单向复合材料的材料选择与设计方面具有现实意义。     

多面体低聚倍半硅氧烷在环氧树脂改性中的应用进展

综述了近几年多面体低聚倍半硅氧烷(POSS)在环氧树脂改性中的应用。POSS单独修饰环氧树脂,可提高其力学性能及热稳定性能;POSS协同9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物等功能性分子一起修饰环氧树脂,可增强其阻燃性能;POSS与碳纳米管、石墨烯等纳米材料共同修饰环氧树脂,可提高纳米材料在环氧树脂中的分散性,改善纳米复合材料的导电能力和黏结强度等性能;POSS与纤维共同修饰环氧树脂,可有效增强纤维与环氧树脂间的界面性能。最后展望了POSS修饰改性环氧树脂的未来方向:开发更简易的引入方式,引入更多样的官能分子,协同多种纳米材料修饰环氧树脂。     

Carbon Nanotube/Carbon Fiber Multiscale Composite: Influence of Interfacial Strength on Mechanical Properties

A promising study to gain the multiscale composite by the growth of carbon nanotubes on the fibers for intralaminar and interlaminar reinforcement was carried out. The mathematical modeling and the numerical simulation of the mechanical response are helpful for the optimum design of the multiscale composite. In this paper, a multiscale modeling approach using a commercial package ANSYS was used to simulate the mechanical response of the complicated material systems. The behavior of two types of interfaces (carbon nanotube/epoxy resin, carbon fiber/equivalent matrix) was described using a cohesive zone model, and the mechanical properties of the multiscale composite were predicted accurately. The mechanism of intralaminar reinforcement was then analyzed numerically. The results reveal that the matrix-dominated properties of the multiscale composite, such as the transverse elastic modulus, increase with the increase of the carbon nanotube/epoxy resin interfacial strength.     

新型碳纤维用原丝——高强高模Lyocell纤维纺丝工艺研究

采用天然高相对分子质量纤维素脱脂棉为原料 ,制备了高强高模纤维素纤维 ( L yocell纤维 ) ,并用此作为碳纤维原丝 ,成功制得了强度优于粘胶基碳纤维的 L yocell基碳纤维。考察了高相对分子质量纤维素的溶解特点 ,纺丝工艺对 L yocell纤维聚集态及性能的影响 ,比较了 L yocell纤维和粘胶原丝的表面及截面形态。实验表明 :高相对分子质量纤维素溶解的静溶胀时间和温度对其溶解有明显的影响 ;纺丝过程中 ,大的气隙长度对提高纤维的性能有利 ;随着凝固浴中 N -甲基吗啉 N -氧化物( NMMO )的浓度增加 ,纤维的强度和模量增加 ,当其在凝固浴中的质量分数达到 10 %时 ,强度模量最大 ,浓度继续增加 ,纤维的力学性能开始下降 ;拉伸比增加 ,L yocell纤维的强度模量增加 ,当拉伸比大于 3.0时 ,纤维的性能略有下降     

Surfactant-Assisted Dispersion of MWCNTs in Epoxy Resin Used in CFRP Strengthening Systems

The epoxy resin used as the bonding agent in carbon fiber-reinforced polymer (CFRP) strengthening systems was modified by the infusion of multiwalled carbon nanotubes (MWCNTs). Two types of surfactants, Triton X-100 and C₁₂E₈, were used to disperse the nanotubes in the epoxy resin employing ultrasonic mixing. Dynamic mechanical analysis and tensile tests were conducted to study the effect of the surfactant-assisted dispersion of nanotubes on the thermal and mechanical properties of epoxy composites. The morphology of the epoxy composites was interpreted using scanning electron microscopy (SEM). Moreover, the effect of surfactant treatment on the structure of nanotubes was investigated by Fourier transform infrared (FT-IR). Based on the experimental results, the tensile strength and the storage modulus of the epoxy resin were increased by 32% and 26%, respectively, by the addition of MWCNTs. This was attributed to the homogeneous dispersion of nanotubes in the epoxy resin according to the SEM images. Another reason for the enhancement in the tensile properties was the reinforced nanotube/epoxy interaction as a result of the surfactant anchoring effect which was proved by FT-IR. A moderate improvement in the glass transition temperature (T _g) was recorded for the composite fabricated using Triton X-100, which was due to the restricted molecular motions in the epoxy matrix. To characterize the temperature-dependent tensile behavior of the modified epoxy composites, tensile tests were conducted at elevated temperatures. It was revealed that the MWCNT modification using surfactant substantially improves the tensile performance of the epoxy adhesive at temperatures above the T _g of the neat epoxy.     

Epoxy Resin Composite Reinforced with Carbon Fiber and Inorganic Filler: Overview on Preparation and Properties

Among carbon fillers, carbon fiber is considered to be an ideal reinforcement for epoxy because of its outstanding electrical, mechanical, and thermal features. Several inorganic fillers such as zinc oxide, titania, and silica are also used in epoxy matrix for property enhancement. The review initially focuses the preparation methods and physical characteristics of epoxy/carbon fiber composite. Afterward, fabrication and properties of epoxy/zinc oxide/titania/silica composites are also conversed. Moreover, the effect of filler dispersion on polymer properties’ improvement is also highlighted. Epoxy/carbon fiber composites are employed more frequently and effectively in defense-related applications compared with epoxy/inorganic nanofiller composite.     

碳纤维湿法缠绕用环氧树脂基体研究

以TDE-85树脂和AFG-90树脂为主体树脂,混合芳香胺为固化剂,研究了一种适合于碳纤维复合材料湿法缠绕成型的树脂配方。结果表明,该树脂的黏度低(＜550 mPa·s)、适用期长,其浇铸体具有优异的力学性能,其拉伸强度为107 MPa,拉伸模量为4．09 GPa,弯曲强度为161 MPa,弯曲模量为3．88 GPa,断裂伸长率超过6%。用其制备的T-700碳纤维缠绕复合材料界面粘接好,NOL环层间剪切强度达到66．8 MPa,拉伸强度达到2．44 GPa。     

Mechanical properties of wood-fiber/toughened isotactic polypropylene composites

This study investigates the mechanical properties of wood-fiber/toughened PP composite modified by physical blending with an EPDM rubber to improve impact toughness. Wood-fiber thermoplastic composites were prepared with a modified PP matrix resin, employing high shear thermokinetic compounding aided with maleated PP for the fiber dispersion. The addition of EPDM improved the impact toughness, while it reduced stiffness and strength properties. To compensate the non-plane strain fracture toughness, the specimen strength ratio (R_sb) was adopted as a comparative measure of fracture toughness. The strength ratio increased with the addition of EPDM, while it decreased with increasing wood-fiber concentration. The work of fracture increased with EPDM level except at large wood-fiber concentration. The effectiveness of the impact modification was assessed with the balance between tensile modulus and unnotched impact energy as a function of wood-fiber concentration. EPDM rubber modification was moderately effective for wood-fiber PP composites. The examination of fracture surfaces showed twisted fibers, fiber breakage, and fiber pull-out from the matrix resin.     

Mechanical properties of silk fibers treated with methacrylamide

Silk fibers were treated with methacrylamide (MAA), and changes in the mechanical properties of the silk fibers were investigated. The breaking load of the silk fibers was almost unchanged, whereas rigidity was markedly increased by the methylmethacrylate (MAA) treatment. Elongation at break of the silk fibers decreased significantly when the fibers were treated with MAA up to polymer add-on (ca. 300%). The cross-sectional area of the MAA-treated silk fiber was given by the addition of the cross-sectional area of the original silk fiber and that of the MAA polymer. The Young's modulus of MAA-treated silk fibers increased linearly with increasing volume fractions of fiber in MAA-grafted silk fibers. The Young's modulus of the MAA polymer in the MAA-treated silk fibers was estimated by extrapolating the relation between Young's moduli and volume fractions of fiber to the zero volume fraction of fiber. The Young's modulus of the MAA polymer in the MAA-treated silk fibers was larger than the sonic modulus measured for an MAA polymer plate. © 1996 John Wiley & Sons, Inc.     

Mechanical properties and multiscale characterization of nanofiber–alumina/epoxy nanocomposites

In contrast to the bulk of published nanocomposite studies, in this study we investigated the mechanical properties of alumina/epoxy nanocomposites manufactured with nanofillers having a fiber or whisker morphology. The article describes how ultrasonic dispersion and in situ polymerization were used to incorporate these 2–4 nm diameter fibers (with aspect ratios of 25–50) into a two‐part epoxy resin (Epon 826/Epicure 9551). The use of untreated and surface‐modified nanoparticles is contrasted, and improvements in both the tensile strength and modulus were observed at low filler loadings. Microstructural characterization of the nanocomposites via multiscale digital image analysis was used to interpret the mechanical properties and was found to be useful for direct comparison with other nanocomposites. In addition, superior performance was demonstrated through comparisons with numerous nanocomposites with nanoparticle reinforcements ranging from carbon nanofibers to spherical alumina particles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Surface Modification of Carbon Fibers by Free Radical Graft‐Polymerization of 2‐Hydroxyethyl Methacrylate for High Mechanical Strength Fiber–Matrix Composites

Free radical polymerization of vinylic monomers in the presence of carbon fibers results in the grafting of polymers onto the carbon fiber surface. Graft polymers cannot be removed by intense washing with good polymer solvents. The density and size of these structures are successfully controlled by reaction conditions. Grafting of the carbon fiber surface with hydroxyethyl methacrylate allows for introducing functional groups suitable for the reaction with an epoxy‐based resin. The resulting fiber‐reinforced composites show enhanced mechanical properties compared to samples prepared from carbon fibers equipped with a standard sizing for epoxy resins. Thus, tensile strength increases by 10%, while interlaminar shear strength improves by 20%.     

Influence of oxygen plasma treatment parameters on the properties of carbon fiber

This study is focused on the impact of oxygen plasma treatment on properties of carbon fibers and interfacial adhesion behavior between the carbon fibers and epoxy resin. The influences of the main parameters of plasma treatment process, including duration, power, and flow rate of oxygen gas were studied in detail using interlaminar shear strength (ILSS) of carbon fiber composites. The ILSS of composites made of carbon fibers treated by oxygen plasma for 1 min, at power of 125 W, and oxygen flow rate of 100 sccm presented a maximum increase of 28% compared to composites made of untreated carbon fibers. Furthermore, carbon fibers were characterized by scanning electron microscopy (SEM), tensile strength test, attenuated total reflectance Fourier transform infrared (ATR-FTIR), and Raman spectroscopy analyses. It was found that the concentration of reactive functional groups on the fiber surface was increased after the plasma modification, as well the surface roughness, which finally improved the interfacial adhesion between carbon fibers and epoxy resin. However, high power and long exposure times could partly damage the surface of carbon fibers and decrease the tensile strength of filaments and ILSS of treated fiber composites.