Characterisation and modelling of CNT–epoxy and CNT–fibre–epoxy composites

Abstract

This research presents an experimental and theoretical investigation on the effects of carbon nanotube (CNT) integration within neat epoxy resin (nanocomposites) and a carbon fabric–epoxy composite (multiscale composites). An approach is presented for the prediction of mechanical properties of multiscale composites. This approach combines woven fibre micromechanics (MESOTEX) with the Mori-Tanaka model which was used for the prediction of mechanical properties of nanocomposites in this research. Nanocomposite and multiscale composite samples were manufactured using cast moulding, resin infusion, and hand lay-up process. The CNT concentrations in the composite samples were from 0 to 5 wt-%. The samples were characterised using tensile, shear and flexural tests. The discrepancy between the theoretical predictions and the experimental observations was hypothesised to be due to dispersion and bonding issues and SEM images are presented in support of the hypothesis.     

Mechanical properties of graphene nanoplatelet/carbon fiber/epoxy hybrid composites: Multiscale modeling and experiments

Because of the relatively high specific mechanical properties of carbon fiber/epoxy composite materials, they are often used as structural components in aerospace applications. Graphene nanoplatelets (GNPs) can be added to the epoxy matrix to improve the overall mechanical properties of the composite. The resulting GNP/carbon fiber/epoxy hybrid composites have been studied using multiscale modeling to determine the influence of GNP volume fraction, epoxy crosslink density, and GNP dispersion on the mechanical performance. The hierarchical multiscale modeling approach developed herein includes Molecular Dynamics (MD) and micromechanical modeling, and it is validated with experimental testing of the same hybrid composite material system. The results indicate that the multiscale modeling approach is accurate and provides physical insight into the composite mechanical behavior. Also, the results quantify the substantial impact of GNP volume fraction and dispersion on the transverse mechanical properties of the hybrid composite while the effect on the axial properties is shown to be insignificant.     

Preparation of multiscale graphene oxide‐carbon fabric and its effect on mechanical properties of hierarchical epoxy resin composite

Graphene oxide (GO) was used to modify the surface of carbon fiber layers through electrophoretic deposition, forming a multiscale reinforcement fabric. By adjusting the experimental parameters, the resulting GO‐carbon fabric showed productive and homogenous distribution of thin and less‐agglomerate GO platelets on carbon fiber surface, remarkably enlarging the surface area and roughness of carbon fabric. To investigate the effect of GO sheets on composites, GO‐carbon fabric and carbon fabric‐reinforced hierarchical epoxy resin composites were respectively manufactured. Mechanical tests demonstrated that after introducing GO flakes on carbon fabric, both the flexural strength and interlaminar shear strength of composite had achieved an increase, especially the interlaminar shear strength rising by 34%. Through fractography analysis, it was found that in pure carbon fabric‐reinforced epoxy composite, the fiber/matrix debonding fracture mechanism predominated, while after the GO decoration on carbon fiber surface, the composite featured a stronger interfacial bonding, leading to the enhancement in mechanical properties of hierarchical epoxy resin composite. POLYM. COMPOS., 37:1515–1522, 2016. © 2014 Society of Plastics Engineers     

Carbon nanotube film/epoxy composites with high strength and toughness

A strong and tough carbon nanotube (CNT)/epoxy composite was fabricated by resin solution impregnation process based on floating catalyst chemical vapor deposition (CVD)–growth CNT films, which had a tensile strength and toughness of 405 MPa and 122 J/g, respectively, and good damping properties as well. Evolution of the composite structure revealed that the CNTs aligned along the tension direction with decreasing orientation angle, and the CNT bundle size enlarged during the tensile test process, which contributed to efficient load transfer among the composite network. Results showed that the proper resin content could bring benefit for strong connections and dense packing of CNTs/bundles, but excessive resin content was unfavorable for improving mechanical properties and conductivities of the nanocomposite. In addition, the resin in CNT film/epoxy composites had a lower crosslink density than that in a neat epoxy system, which endowed the CNT composites with large deformation capability. POLYM. COMPOS., 38:588–596, 2017. © 2015 Society of Plastics Engineers     

碳纤维三维网络体增强环氧树脂复合材料的性能

以酚醛树脂粘结短切碳纤维(SCF)并炭化制得碳纤维三维网络增强体(CFNR),再采用真空袋成型法浸入环氧树脂(EP)制得新型EP/CFNR复合材料。通过显微镜观察CFNR和复合材料的微观结构,采用万能试验机测试力学性能,以及用电阻仪测定导电性能等方法对复合材料进行了评价。结果表明,炭化后的酚醛树脂将SCF粘结成连续的三维网络结构,EP/CFNR复合材料中SCF间有明显可见的炭质粘结点;当SCF质量分数为7.3%时,EP/CFNR复合材料较纯EP,EP/SCF复合材料的弯曲强度分别提高33%,29%,压缩强度分别提高23%,10%,同时,其体积电阻率是EP/SCF复合材料的1/45。     

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     

Exploration of Epoxy Resins,Hardening Systems,and Epoxy/Carbon Nanotube Composite Designed for High Performance Materials: A Review

Epoxy resins, is an important class of reactive polymers, have been reported to be toughened by nanoparticles. Carbon nanotube is a tubular cylinder ofcarbonatoms having extraordinary mechanical, electrical, and thermal properties. In this article, present state of epoxy/carbon nanotube composite is given. Types of epoxy and hardening agents commonly used in composite processing have been thrashed out. Frequently used fabrication techniques are discussed with particular emphasis on evaluating dispersion state of nanotube. Epoxy/carbon nanotube composites offer substantially improved properties compared to traditional fiber-reinforced epoxy composites. Finally, potential relevance for efficiently transforming filler properties to matrix facilitating aerospace relevance is conversed.     

Study on the mechanical properties and microstructure of high-performance carbon fiber/epoxy composites

A high-toughness epoxy has been prepared using carboxyl-terminated butadiene acrylonitrile (CTBN) as a toughening agent to modify the AG-80 epoxy resin. High-performance carbon fiber/epoxy (CF/EP) composites are fabricated using the CTBN-toughened epoxy resin as the matrix and two types of CF, namely, T800SC and T800HB, as reinforcement. The mechanical properties of the matrix, surface properties of the CFs, tensile properties, and fracture morphologies of the composites are systematically investigated to elucidate the key factors influencing interfacial bonding in high-performance CF/EP composites. The results reveal that the most significant improvement in toughness is achieved when the CTBN content is 6.90 wt.% in the epoxy resin. Owing to the high content of polar functional groups and excellent surface wettability of T800SC, the T800SC/EP composite exhibits superior mechanical properties compared with the T800HB/EP composite.     

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     

Electromagnetic Interference Shielding of Polymer/Nanodiamond,Polymer/Carbon Nanotube,and Polymer/Nanodiamond–Carbon Nanotube Nanobifiller Composite: A Review

In this review, properties and potential of carbon nanotube, nanodiamond, and nanodiamond–carbon nanotube hybrid nanobifiller have been discussed with reference to electromagnetic interference shielding materials. The nanodiamond and carbon nanotube nanofiller and nanodiamond–carbon nanotube nanobifiller have outstanding electrical, thermal, and mechanical features. Main focus of review was electromagnetic interference shielding phenomenon and its implication in polymer/nanodiamond, polymer/carbon nanotube, and polymer/nanodiamond–carbon nanotube nanobifiller composite. The epoxy/nanodiamond, epoxy/carbon nanotube, and epoxy/nanodiamond–carbon nanotube composites have been discussed with electromagnetic interference shielding shielding features. Thus, considerable enhancement in electromagnetic interference shielding shielding features was observed using higher nanodiamond, carbon nanotube, and nanodiamond–carbon nanotube loadings. Significance and future potential of these polymeric composite are specified.     

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.     

快速固化环氧树脂/碳纤维复合材料的性能

利用差示扫描量热分析仪研究了一种快速固化环氧树脂体系的固化工艺参数,确定了以真空辅助树脂灌注工艺制备快速固化环氧树脂/碳纤维复合材料的成型方法,并与常规固化环氧树脂体系制备的碳纤维复合材料进行对比,采用傅里叶变换红外光谱仪对两种材料的树脂基体进行了分析,考察了两种复合材料的纤维含量、孔隙率及力学性能,最后通过扫描电子显微镜观察了快速固化树脂基体与碳纤维的界面结合性。结果表明,快速固化树脂在99℃下固化6 min后固化度可达96%,能够大幅缩减碳纤维复合材料的成型时间,以其制备的碳纤维复合材料拉伸强度比常规固化环氧树脂复合材料高11.20%,弯曲强度高16.92%,纵横剪切强度高7.44%,快速固化树脂与碳纤维界面结合性良好。     

碳纤维复合材料发动机壳体用高性能树脂基体的研制

在综合考虑树脂黏度、力学性能、耐热性能的基础上。开发了适用于碳纤维复合材料火箭发动机壳体温法缠绕成型工艺用耐高温和韧性环氧树脂基体。用差示扫描式量热法(DSC)、傅里叶红外光谱FT—IR等分析技术对该韧性树脂基体的固化反应动力学参数、树脂基体固化物的性能和复合材料的性能进行了系统的研究。结果表明，该韧性树脂基体黏度低，适用期长，韧性好，与碳纤维界面粘接强度高，所制得的复合材料火箭发动机壳体纤维强度转化率高。为今后相关方面的研究指明了方向。     

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.     

Grafting of Amine-Functionalized Multiwall Carbon Nanotubes with Free Acid Anhydride in Carboxylic Acid Modified Epoxy

The novel approach was developed for grafting of amine-functionalized multiwall carbon nanotubes with carboxylic acid, modified epoxy resin containing free acid anhydride group, which gives enhanced grafting. The amine-functionalized multiwall carbon nanotubes was dispersed in benzyl alcohol by sonication at 60°C and incorporated with modified epoxy. The amine functioned Multiwall carbon nanotubes were controlled loading of carboxylic acid, modified epoxy resin-grafted with amine-functionalized multiwalll carbon nanotube polymer composites. These were characterized by FTIR, SEM. TEM and NMR analysis. The improved mechanical properties observed for low amounts of MWCNT loading due to uniform dispersion.     

Multifunctional Characteristics of Glass Fiber-Reinforced Epoxy Polymer Composites with Multiwalled Carbon Nanotube Buckypaper Interlayer

In this work, multiwalled carbon nanotube buckypaper (MWCNT-BP) was inserted at the middle-plane of glass fiber/epoxy resin prepregs to obtain three-phase nanostructured composite. Preliminary tests conducted by differential scanning calorimetry and thermogravimetric analyses (TGA) revealed that the proposed curing cycle to prepare the laminates in a hot compression-molding machine was appropriated. The mechanical properties of the BP-based composite studied by short beam shear and compression shear tests presented no improvements compared to the base laminate. On the other hand, the thermal properties of the nanostructured composite improved as demonstrated by dynamical mechanical analyses and TGA. Besides, the reflectivity results revealed an average value of −12.2 dB in the X-band with a maximum attenuation of 99.4% of the incident wave at 9.5 GHz. The improvements in both thermal and electromagnetic properties demonstrate the potential for both structural and multifunctional applications of the obtained BP-composite. POLYM. ENG. SCI., 60:740–751, 2020. © 2020 Society of Plastics Engineers     

Significance of Carbon Nanotube in Flame-Retardant Polymer/CNT Composite: A Review

In this review, flame-retardant characteristics of polymer/carbon nanotube composite have been focused. Nonflammability behavior of carbon nanotube filler with different types of polymer matrices has been discussed. In addition, thermal, mechanical, and electrical properties of these materials have also been argued. Main types of polymers considered are epoxy, polystyrene, polyaniline, polypropylene, and polyurethane. Considerable enhancement in nonflammability properties of polymers with carbon nanotube was studied using limiting oxygen index measurement, UL 94 tests, and cone calorimetry. Toward the end, significance of flame-retardant composites in aerospace, electronics, radar absorbing materials, electromagnetic shielding, and wind turbine blades has been conversed.     

Structure and properties of aeronautical composites using carbon nanotubes/epoxy dispersion as nanocomposite matrix

The structure and properties of hybrid multiscale composites containing carbon nanotubes (CNTs) was reported. CNTs were dispersed in epoxy by using high energy ultrasonication, followed by the fabrication of CNT hybrid composites via resin transfer molding (RTM) processing. The processability of CNTs/epoxy systems was explored by a capillary experiment. The dependences of mechanical and electrical properties of the hybrid composites on CNT content were investigated. Microscopic observation confirms the formation of CNTs percolation network. The different roles of CNT networks in mechanical reinforcement and electrical amelioration were analyzed. One explanation based on the dispersion and distribution of CNTs is proposed. It is found that the variations of the hybrid composites with respect to mechanical and electrical properties are attributed to the hierarchical structure in the hybrid composites. As far as the hybrid multiscale composites produced via RTM process is concerned, the formation of CNT percolation network, subjected to dynamic impregnation, is hindered by the presence of continuous fibrous reinforcement. The hierarchical structure influenced by several competing factors reveals great potential in being able to tailor the structural and functional performance of the CNT hybrid composites. The effects of CNTs on the dimensional stability of polymer based composites are also assessed. POLYM. COMPOS., 34:1690–1697, 2013. © 2013 Society of Plastics Engineers     

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。     

Technical Relevance of Polymer/Cement/Carbon Nanotube Composite: Opportunities and Challenges

The polymer/cement/carbon nanotube composites are known for piezoelectric properties in intelligent structures. Polymers are also used to fulfill deficiencies in carbon nanotube/cement mortars. High-impact polystyrene has replaced sand to enhanced properties like energy consumption, waste disposal, and environmental pollution. Spray-applied fire-resistive material in engineered cementitious composite may overcome drawbacks of conventional brittle composite. Carbon nanotube is used as nanofillers in ordinary Portland cement due to superior mechanical properties. Cementitious polymer/carbon nanotube composite has potential to determine heat-dependent and self-sensing capacity of composites. Smart properties of composites are measured using conductivity measurement. Polymers are also used for making better carbon nanotube dispersion.