Structure and properties of CE/CTBN/EP blends: II. Effect of EP on the mechanical properties and thermostability of the CE/CTBN system

Carboxyl‐terminated butadiene‐acrylonitrile rubber (CTBN) has often been used to improve the toughness of cyanate ester (CE) resin while sacrificing modulus and thermostability. In this paper, the addition of the appropriate amount of epoxy resin (EP) to the CE/CTBN system is shown to not only increase the modulus and thermostability of the blend, but also improve the toughness. The values of impact strength showed a maximum for the CE/CTBN/EP 100/5/5 blend. The temperature of 10 % weight loss (T₁₀) improves from 376 °C for CE/CTBN 100/5 to 407 °C for the CE/CTBN/EP 100/5/2.5 blend. It is proposed that addition of the appropriate amount of EP can decrease the mobility and increase the stability of CTBN via the reaction between the terminal carboxyl group of CTBN and the hydroxyl group of EP. But a very high EP concentration will decrease the crosslinking density of CE, consequently reducing the mechanical properties and thermostability of the blends. Copyright © 2004 Society of Chemical Industry     

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。     

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.     

LDPE/SEBS/CB电致形状记忆复合材料的结构与性能

通过熔融共混法将热塑性弹性体氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物(SEBS)和低密度聚乙烯(LDPE)制成形状记忆聚合物(SMP)材料;在SMP材料中填充导电炭黑(CB),制成具有电致形状记忆特性的LDPE/SEBS/CB复合材料。通过SEM、DSC分析和力学性能、电性能、记忆性能测试,研究了CB含量对电致SMP材料结构与性能的影响。结果表明:当CB含量达到20%时,LDPE/SEBS/CB复合形状记忆材料的体积电阻率降至103Ω·cm左右,CB的导电网络趋于稳定;并且LDPE/SEBS/CB(2:2:1)复合形状记忆材料的形状固定率约90%,常温拉伸和高温拉伸时均表现出较高的形状回复率(约90%),拉伸模量约170MPa,拉伸强度约9.5MPa,断裂伸长率约400%。     

Mechanical and thermal transmission properties of carbon nanofiber‐dispersed carbon/phenolic multiscale composites

The present article reports the development and characterization of carbon nanofiber (CNF)‐incorporated carbon/phenolic multiscale composites. Vapor‐grown CNFs were dispersed homogeneously in to phenolic resin using an effective dispersion route, and carbon fabrics were subsequently impregnated with the CNF‐dispersed resin to develop carbon fiber/CNF/phenolic resin multiscale composites. Mechanical and thermal transmission properties of multiscale composites were characterized. Elastic modulus and thermal conductivity of neat carbon/phenolic and multiscale composites were predicted and compared with the experimental results. It was observed that incorporation of only 1.5 wt % CNF resulted in 10% improvement in Young's modulus, 12% increase in tensile strength, and 36% increase in thermal conductivity of carbon/phenolic composites. Fracture surface of composite samples revealed the formation of stronger fiber/matrix interface in case of multiscale composites than neat carbon/phenolic composites. Enhancement of above properties through CNF addition has been explained, and the difference between the predicted values and experimental results has been discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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。     

环氧树脂对PA6/EPDM-g-MAH共混体系性能的影响

将两种不同型号的环氧树脂（EP(903)、EP(619D)）分别与PA6/EPDM-MA体系进行共混,制备了PA6/EPDM-MA/EP三元共混物。通过力学测试、动态流变(DMA)、差示扫描量热法（DSC）研究了不同EP添加量和环氧当量对PA6/EPDM-MA/EP共混体系性能的影响。实验结果表明：添加EP可以提高PA6/EPDM-MA共混物的拉伸强度,缺口冲击强度,并随着EP含量的增加而增加;而PA6/EPDM-MA/EP三元共混体系的动态储能模量（G′）,复合黏度（η*）随着EP含量的增加而增大,损耗因子（tanδ）减小;结晶度比未加环氧的共混物的结晶度稍高,并且随着环氧含量增加先增加后降低。此外,添加EP(903)的共混物各种性能变化比EP(619D)快。     

氰酸酯/环氧树脂体系的形状记忆效应研究

以不同配比的CE/EP(氰酸酯/环氧树脂)作为共聚体系制备耐温型SMP(形状记忆聚合物)。采用凝胶时间、红外光谱(FT-IR)和弯曲模型等测试手段,确定了合成CE/EP基SMP的最佳工艺条件和形状记忆行为。研究结果表明:当m(CE)∶m(EP)=1∶0.7、固化工艺为"抽真空/30 min→160℃/60 min→190℃/45 min"时,CE/EP共聚体系可完全固化,并能生成网状交联结构的无定形透明态SMP;此时,该SMP具有良好的形状记忆行为,并且其形状记忆行为的可恢复率相对最大。     

Effects of process conditions on Young's modulus and strength of extrudate in short‐fiber‐reinforced polypropylene

We examined the effects of process conditions on Young's modulus and tensile strength of extruded short‐fiber reinforced thermoplastics. With increasing extrusion ratio and decreasing extrusion temperature, the fiber alignment increases, the mean fiber length decreases, and the mechanical properties of the matrix are improved. The orientation parameter, mean fiber length, Young's modulus, and tensile strength of the matrix are described as a function of extrusion ratio and extrusion temperature. The models proposed by Fukuda and Kawata, and Fukuda and Chou are applied to predict Young's modulus and tensile strength of the composites using orientation parameter. By comparing the predicted Young's modulus and tensile strength with experimental results, the validity of the models is examined. The prediction of Young's modulus agreed quit with the experimental results. The tensile strength of composite extruded below the melting point nearly matched that of the neat matrix. There is no the strengthening effect of the fiber since the angle between fracture surface and fiber direction is very small. POLYM. COMPOS. 28:29–35, 2007. © 2007 Society of Plastics Engineers     

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.     

纳米CaCO_3对CE及CE/EP基体的改性研究

通过力学性能测试和扫描电镜、热重分析以及红外光谱测试研究了纳米CaCO3的加入量对氰酸酯(CE)及CE/环氧(EP)基体力学性能及热性能的影响。结果表明,适量的纳米CaCO3的加入,可有效地改善CE或CE/EP基体的韧性和强度。当纳米CaCO3的质量分数为3%时,两改性体系的冲击强度和拉伸模量均达到最大值,CE/EP/CaCO3体系较CE/CaCO3体系具有更高的冲击强度(7.8kJ/m2)和较低的拉伸模量(100.5GPa)。纳米CaCO3的加入有利提高基体的热稳定性,但CE/EP/CaCO3三元体系的热稳定性仍明显低于纯CE或CE/CaCO3二元体系。     

Enhancement of PVC/ENR blend properties by poly(methyl acrylate) grafted oil palm empty fruit bunch fiber

Effect of oil palm empty fruit bunch (OPEFB) fiber and poly(methyl acrylate) grafted OPEFB on several mechanical properties of poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blends were studied. The composites were prepared by mixing the fiber and the PVC/ENR blends using HAKEE Rheomixer at the rotor speed of 50 rpm, mixing temperature 150°C, and mixing period of 20 min. The fiber loadings were varied from 0 to 30% and the effect of fiber content in the composites on their ultimate tensile strength (UTS), Young's modulus, elongation at break, flexural modulus, hardness, and impact strength were determined. An increasing trend was observed in the Young's modulus, flexural modulus, and hardness with the addition of grafted and ungrafted fiber to the PVC/ENR blends. However the impact strength, UTS, and elongation at break of the composites were found to decrease with the increase in fiber loading. An increase in elongation at break and UTS and decrease in the flexural and Young's modulus was observed with the addition of PMA‐g‐OPEFB fiber compared to ungrafted fiber. This observation indicates that grafting of PMA onto OPEFB impart some flexibility to the blend. The morphology of cryogenically fractured and tensile fracture surfaces of the composites, examined by a scanning electron microscope shows that the adhesion between the fiber and the matrix is improved upon grafting of the OPEFB fiber. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

液体端羧基丁腈橡胶改性氰酸酯／玻璃纤维复合材料的性能研究

用液体端羧基丁腈橡胶(CTBN)对氰酸酯树脂(CE)进行了增韧改性,通过树脂体系的凝胶时间曲线和DSC曲线确定了体系的固化工艺,并制备了玻璃纤维(GF)增强复合材料。CTBN改性后的CE树脂及复合材料具有良好的力学性能,其中固化树脂的弯曲强度和冲击强度分别提高了34.6%和48%,复合材料的弯曲强度和冲击强度分别提高了11.4%和21.3%,这来源于CTBN对氰酸酯树脂的增韧作用及与GF良好的粘接性能。     

Preparation of polyester resin/graphene oxide nanocomposite with improved mechanical strength

Graphene oxide (GO) has attracted huge scientific interest due to its unique physical and chemical properties as well as its wide‐scale applicability including facile synthesis and high yield. Here, we report preparation of nanocomposites based on GO and unsaturated polyester resin (PE). The synthesized samples were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and tensile strength measurements. A good dispersion of the GO sheets within the resin matrix was observed from the morphological analysis. A significant enhancement in mechanical properties of the PE/GO composites is obtained at low graphene loading. Around 76% improvement of tensile strength and 41% increase of Young's modulus of the composites are achieved at 3 wt % loading of GO. Thermal analysis of the composite showed a noticeable improvement in thermal stability in comparison to neat PE. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Processability and mechanical properties of ternary composites PP/EPDM/GF

The enhancement of the mechanical properties of neat PP is achieved by the addition of glass fibers and EPDM rubber. The Young's modulus and notched Charpy impact strength of the composites obtained are improved with respect to the original polymer, leading to a new composite material with a very good balance of toughness and rigidity properties. The tensile behavior of these multiphase systems is successfully compared with theoretical predictions using the Halpin‐Tsai/Nielsen theory for uniaxially short fiber composites, which considers the matrix as a blend with spherical particles and can predict the tensile modulus considering an average fiber orientation angle. An accurate morphological study performed by scanning electron microscopy (SEM) shows a very good dispersion of the rubbery phase into the neat matrix. No special affinity between the rubber and the fibers is reported. The good dispersion and the small particle diameter indicate the good processability of the ternary systems studied.     

EP/BMI树脂基碳纤维复合材料的制备与性能表征

以环氧树脂(EP)、双马来酰亚胺(BMI)、4,4’-二氨基二苯砜(DDS)和短切碳纤维(SCF)等为主要原料制备了EP/BMI/DDS/SCF复合材料,并研究了SCF添加量对复合材料力学性能和热性能的影响。结果表明,当SCF添加量为0.25 %(质量分数,下同)时,EP/BMI/DDS/SCF复合材料的力学性能提高最大,其拉伸强度、弯曲强度、弯曲模量和缺口冲击强度比未添加SCF时的EP/BMI/DDS复合材料分别提高了48.52 %、32.15 %、25.77 %以及150.91 %;此外,SCF的加入有助于提高复合材料的热性能。     

环氧树脂/短切碳纤维复合材料性能研究

制备出了短切碳纤维增强TDE-85环氧树脂复合材料,研究了碳纤维的含量对复合材料力学性能和耐热性能的影响。结果表明,碳纤维的加入有利于复合材料力学性能和耐热性能的提高,并在碳纤维含量为0.25%时,复合材料的拉伸强度、冲击韧性、弯曲强度和弯曲模量达到最大,分别提高了29.33%、25.31%、30.28%和68.93%。此外,对复合材料的弯曲断裂面进行了微观形貌分析,结果表明一定量的碳纤维可以较好地分散在树脂基体中,同时,碳纤维原丝和树脂基体的界面结合比较弱,主要依赖于两相之间的物理嵌合。     

Influence of complexing treatment and epoxy resin coating on the properties of aramid fiber reinforced natural rubber

In this work, natural rubber/aramid fiber (NR/AF) composites were prepared with master batch method. AF was modified by using epoxy resin (EP) and accelerator 2‐ethyl‐4‐methylimidazole (2E4MZ) through surface coating on the basis of the complexing treatment with CaCl₂ solution. Hydroxyl‐terminated liquid isoprene rubber (LIR) was regarded as a compatibilizer between EP and NR. It is found that the crystallinity on AF surface is decreased by complexing reaction with CaCl₂ solution. Swelling and mechanical properties of the vulcanized composites, such as swelling degree, tensile and tear strength, tensile modulus at 300% elongation, are measured, and the tensile fracture morphology and dynamic mechanical analysis of the composites are investigated. The results show that the mechanical properties of composites with modified fibers are improved obviously and interfacial adhesion between matrix and the fiber is enhanced, especially for the AF coated with EP and imidazole. The best comprehensive mechanical properties of the composites are obtained with using CaCl₂‐EP/2E4MZ system when the ratio of m(EP)/m(AF) is 3%. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42122.     

纳米SiO2/竹纤维/环氧树脂复合材料性能研究

将竹纤维加入到环氧树脂中以形成增强环氧复合材料,研究了竹纤维竹粉和纳米二氧化硅（SiO2）对环氧树脂的力学性能和耐溶剂浸蚀性能的影响。竹纤维含量为15%时,竹纤维/环氧树脂的冲击强度比纯环氧树脂提高50%。纳米SiO2能同时增强和增韧竹纤维/环氧树脂,并提高其耐溶剂浸蚀性能,纳米SiO2含量为4%时,纳米SiO2/竹纤维/环氧树脂三元复合材料的冲击和拉伸强度分别比未添加纳米SiO2的竹纤维/环氧树脂提高40%和30%。当纳米SiO2/竹纤维/环氧树脂的质量比为4/15/85时,三元复合材料的综合性能较好。     

热处理对EP/CF及EP/CF/GF复合材料力学性能的影响

采用真空辅助树脂转移模塑（VARTM）技术制备了环氧树脂/碳纤维（EP/CF）和环氧树脂/碳纤维/玻璃纤维毡（EP/CF/GF）复合材料。测试了两种纤维铺层方式中树脂流动距离的平方与流动时间的关系,对两种铺层纤维体系的渗透率进行了研究对比;将两种复合材料进行高温处理,并且对其高温处理前后的力学性能进行分析;利用扫描电子显微镜（SEM）观察了复合材料的拉伸断口形貌。结果表明,EP/CF/GF中GF毡的松散结构使树脂更易流动;高温热处理造成了EP/CF弹性模量和拉伸应变的降低,其中弹性模量降低了9.97 %、拉伸应变降低了11.36 %,但对EP/CF/GF的影响较小;GF毡的加入造成了2种复合材料弯曲性能的下降;未经处理的复合材料断口表面光滑,而热处理后的复合材料断口表面粗糙且有大量基体附着。