含噁嗪环硅烷偶联剂对石英纤维/含硅芳炔复合材料性能的影响

从石英纤维(QF)、含硅芳炔树脂(PSA)分子结构特点出发,设计并合成了一种含有噁嗪环和端炔的新型硅烷偶联剂(BCA),并以BCA改善QF/PSA复合材料的界面性能。采用差示扫描量热分析(DSC)、红外光谱分析(FT-IR)、X-射线电子能谱(XPS)及扫描电镜(SEM)等测试手段表征了BCA与QF/PSA复合材料的相互作用和界面改性效果。结果表明:BCA能够分别与PSA和QF形成良好的化学键合,改善复合材料的界面黏结;经w=2.0%的BCA处理后,QF/PSA复合材料的层间剪切强度、弯曲强度分别较未处理前提高了69.1%和68.8%。     

耐高温端乙炔基聚醚酰亚胺改性含硅芳炔树脂

采用预共聚法,以含硅芳炔树脂(PSA)和端乙炔基聚醚酰亚胺(PEI)为原料,制备了端乙炔基聚醚酰亚胺改性的含硅芳炔(PEI-PSA)树脂及其与T300碳纤维平纹布的复合材料T300/PEI-PSA。通过动态热机械分析(DMA)和X射线能谱仪(EDS)研究了溶剂、溶液浓度、反应温度对预共聚反应的影响,确定了预共聚反应的最佳条件,得到了均匀分散的PEI-PSA树脂。通过红外光谱(FT-IR)、核磁共振氢谱(1 H-NMR)、差示扫描量热(DSC)、热失重(TG)、DMA和EDS等表征了PEI、PEI-PSA树脂及T300/PEI-PSA复合材料的结构和性能。结果表明,当PEI质量分数为20%时,PEI-PSA树脂浇铸体的弯曲强度达44.5 MPa,较PSA树脂浇铸体提高了90.2%;T300/PEI-PSA复合材料的弯曲强度达602.7 MPa,较T300/PSA复合材料的弯曲强度提高了124%。     

复合改性竹纤维/聚丙烯复合材料的制备与性能研究北大核心CSCD

为改善竹纤维(BF)与聚丙烯(PP)的界面结合,采用碱(NaOH)和异氰酸酯偶联剂(TDI)复合改性竹纤维,制备BF/PP复合材料。分析了竹纤维改性前后主要化学成分、热行为及化学结构变化,考察了竹纤维改性对复合材料维卡软化点(VSP)和动态热力学性能影响,用扫描电镜对复合材料断面进行了观察,最后探讨了改性竹纤维添加量对复合材料力学性能的影响。结果表明:BF经复合改性后,表面形成了氨酯键结构,竹纤维素晶体尺寸和结晶度增大,竹纤维的最快热降解温度和复合材料的VSP分别提高了20℃和4.5℃。SEM、DMA分析显示,竹纤维复合改性改善了两相界面结合,利于力学性能提高。拉伸实验表明,在复合改性竹纤维添加比例为40%时,复合材料综合性能最佳,其冲击强度、拉伸强度和弯曲强度分别增加了21.6%、23.3%和27.8%,拉伸模量和弯曲模量分别增加了24.2%和30.4%。     

复合改性竹纤维/聚丙烯复合材料的制备与性能研究

为改善竹纤维(BF)与聚丙烯(PP)的界面结合,采用碱(NaOH)和异氰酸酯偶联剂(TDI)复合改性竹纤维,制备BF/PP复合材料。分析了竹纤维改性前后主要化学成分、热行为及化学结构变化,考察了竹纤维改性对复合材料维卡软化点(VSP)和动态热力学性能影响,用扫描电镜对复合材料断面进行了观察,最后探讨了改性竹纤维添加量对复合材料力学性能的影响。结果表明:BF经复合改性后,表面形成了氨酯键结构,竹纤维素晶体尺寸和结晶度增大,竹纤维的最快热降解温度和复合材料的VSP分别提高了20℃和4.5℃。SEM、DMA分析显示,竹纤维复合改性改善了两相界面结合,利于力学性能提高。拉伸实验表明,在复合改性竹纤维添加比例为40%时,复合材料综合性能最佳,其冲击强度、拉伸强度和弯曲强度分别增加了21.6%、23.3%和27.8%,拉伸模量和弯曲模量分别增加了24.2%和30.4%。     

环氧氯丙烷修饰的对位和间位芳纶涂覆剂研究

制备了具有环氧丙基侧链的对位芳纶(PPTA-ECH)和间位芳纶(PMIA-ECH),并将其用做对位芳纶(PPTA)织物/环氧树脂复合材料中PPTA织物的涂覆剂。采用场发射扫描电子显微镜(FE-SEM)及XPS等方法对PPTA织物表面的PPTA-ECH涂层结构进行了表征。考察了PPTA-ECH和PMIA-ECH涂覆的PPTA织物/环氧树脂复合材料的层间剪切强度和面内剪切强度,并与未经涂覆的PPTA织物复合材料的性能作比较。结果表明,PPTA-ECH和PMIA-ECH可显著改善PPTA织物和环氧树脂之间的界面性能。涂覆了PPTA-ECH及PMIA-ECH的PPTA织物/环氧树脂复合材料的层间剪切强度(ILSS)比未经涂覆的复合材料分别提高了26.20%和14.76%,面内剪切强度(ISS)分别提高了26.98%和11.86%。由于PPTA-ECH对PPTA纤维具有更强的亲和能力,因此PPTA-ECH在层间剪切强度和面内剪切强度方面的增强效果均优于PMIA-ECH。对PPTA-ECH在PPTA纤维表面铺展与吸附及对复合材料的增强机理也进行了初步探讨。作为新型涂覆剂,PPTA-ECH在对位芳纶复合材料的开发应用方面具有潜在的应用前景。     

聚甲基二间苯二乙炔基硅烷改性二氧化双环戊二烯环氧树脂及其复合材料的性能

用聚甲基二间苯二乙炔基硅烷树脂（PSA）改性二氧化双环戊二烯（R-122环氧树脂）得到R-122/PSA树脂体系,并以该树脂为基体制备了玻璃纤维复合材料。通过FT-IR、DSC和TGA研究了R-122/PSA树脂的固化反应及其耐热性能,同时研究了R-122/PSA基复合材料的力学性能、耐热性能、介电性能和耐水性能。结果表明：改性树脂在高温下保持了良好的耐热性能,mPSA/mR-122=0.2的固化物在800°C下质量保留率比纯R-122树脂的提高了30%。所制备的复合材料常温下弯曲强度达到735 MPa,220°C下的弯曲强度达到418.4 MPa,不仅保留了良好的力学性能,而且耐热性能得到了很好的提升,同时其浸泡96 h后的吸水率仅为0.65%,耐水性能优异。     

阻燃玻纤增强尼龙66的制备及性能研究

研究了用环保型阻燃剂溴化聚苯乙烯(PBS)、三氧化二锑(Sb2O3)、玻璃纤维(GF)以及功能助剂通过双螺杆挤出机制备出27%(wt)玻纤含量的高性能环保型阻燃增强尼龙66(PA66)复合材料。DSC和TGA结果表明,玻纤和阻燃剂等填料阻碍PA66结晶过程中分子链段的运动,降低其结晶能力,同时降低了复合材料的热稳定性;SEM结果表明复合材料各组分之间的界面粘结力较强,填料在基体中的分散性较好;力学和阻燃性能测试结果表明,与PA66相比,复合材料的拉伸强度、弯曲强度和弯曲模量分别提高了100%、110%和250%,阻燃性能达到V-0级(0.8 mm)。     

机械混炼过程对天然橡胶/有机蒙脱土纳米复合材料结构的影响

采用机械混炼插层法制备天然橡胶(NR)/有机蒙脱土(OMMT)纳米复合材料,研究混炼过程对复合材料结构的影响。结果表明,剪切作用越强并不越有利于大分子链的插层,当辊距为3 mm时,适当增加薄通的次数,有益于分子链插入蒙脱土层间。当薄通次数达到40次时,可形成剥离型的纳米复合材料。且在共混过程中加入偶联剂,可使得蒙脱土与橡胶间的化学交联的比例提高,从而改善复合材料的物理机械性能和热氧老化性能。     

耐高温可溶性聚酰亚胺树脂及其复合材料

制备了2种耐高温可溶型聚酰亚胺树脂(PI-1, PI-2)及其复合材料, 系统研究了树脂的工艺性, 纯树脂固化物的热性能及其复合材料的界面形貌、 介电性能和力学性能. 研究结果表明, 树脂低聚物在极性非质子溶剂中具有良好的溶解性, 且熔体黏度较低, 表明其具有优异的加工性能. 两种树脂固化物在空气中的5%热失重温度均高于550 ℃, PI-1树脂的玻璃化转变温度(T_g)为430 ℃, PI-2树脂的T_g为380 ℃. 石英纤维/PI-1和石英纤维/PI-2复合材料具有较低的介电常数和介电损耗. 碳纤维/PI-1复合材料在420 ℃下的弯曲强度保持率可达62%, 层间剪切强度保持率可达48%, 具有较优异的高温力学性能. 采用普通模压工艺制备了厚度高达45 mm的复合材料制件, 进一步证明这2种树脂具有优异的工艺性.     

含磷聚芳醚酮颗粒层间增韧碳纤维/双马树脂RTM复合材料

选用一种在RTM双马来酰亚胺树脂(BMI)注射温度下不溶解的含磷聚芳醚酮(P-PAEK)热塑性树脂作为增韧剂,制备层间颗粒增韧碳纤维增强双马来酰亚胺树脂基复合材料.研究了不同热塑树脂含量对树脂浇铸体冲击性能的影响,利用扫描电镜表征了复相体系的微观形貌并分析其增韧机制,并通过层间断裂韧性测试表征了RTM双马树脂基复合材料增韧前后的层间韧性性能.结果表明,当附载热塑颗粒面密度为2 g/m2时,复合材料的I型层间断裂韧性(GIC)为0.54 k J/m2,II型层间断裂韧性(G_(IIC))为1.36 k J/m~2,较未增韧复合材料分别提升约56%和42%.增韧后的复合材料在保持原有力学性能的同时,其冲击后压缩强度(CAI)提升约29%,层间剪切强度达到111.7 MPa.     

Effect of internal mold release agent on flexural and inter laminar shear properties of carbon and glass fabric reinforced thermoset composites

The study is focused on thermoset composites reinforced with carbon and glass woven fabrics. Two types of thermoset resins, for example, epoxy and vinyl ester were used as the matrix. Varying concentrations of internal mold releasing (IMR) agent was used in the resin. The composites were cured both at room temperature and at 80°C. The flexural properties were studied using 3‐point bending test method. Further theinter‐laminar shear strength (ILSS) was investigated using the short beam shear strength test based on 3‐point bending. The flexural modulus of room temperature cured epoxy resin is higher than that of high temperature cured epoxy resin and cured vinyl ester resin. The flexural modulus is lowest for 1% IMR sample in epoxy system and the modulus for 0% and 2% epoxy are not significantly different. Lowest flexural strength and modulus can be observed for the combination of reinforcement and curing conditions for samples containing 1% IMR for the epoxy systems. Carbon fiber is found to be less compatible with the vinyl ester resin system and the addition of IMR to the resin degraded the properties further. Inter‐laminar shear strength for epoxy‐based composites is not much affected by presence of IMR, but in case of vinyl ester based composites there is a decrease in ILSS on addition of IMR agent. The study explains variation in flexural properties on addition of IMR and change of curing conditions. These results can be used for ascertaining variation in mechanical properties in real use.     

Flexural behavior of unidirectional polyethylene–glass fiber–PMMA hybrid composites

Unidirectional hybrid laminates based on glass fibers (GF) and high performance polyethylene fibers (PEF) were prepared with a partially polymerized methyl methacrylate (MMA) matrix at room temperature followed by heating at 55°C for the stipulated time (well below the softening point of PEF). The ultimate flexural strength (UFS), flexural modulus (FM) and interlaminar shear strength (ILSS) of the composites were determined and analyzed. An interesting observation of the study was the change in flexural behavior, which was largely dependent on the position of GF and PEF ply/plies in the compression and tension sides. When the ply/plies of PEF were at the tension side, the UFS and FM showed a higher value than that when GF plies were in the tension side of the hybrid composites. The ILSS also follows the same trend regarding the position of the GF and PEF plies.     

Effect of fiber length and composition on mechanical properties of carbon fiber‐reinforced polybenzoxazine

The mechanical strength and modulus of chopped carbon fiber (CF)‐reinforced polybenzoxazine composites were investigated by changing the length of CFs. Tensile, compressive, and flexural properties were investigated. The void content was found to be higher for the short fiber composites. With increase in fiber length, tensile strength increased and optimized at around 17 mm fiber length whereas compressive strength exhibited a continuous diminution. The flexural strength too increased with fiber length and optimized at around 17 mm fiber length. The increase in strength of composites with fiber length is attributed to the enhancement in effective contact area of fibers with the matrix. The experimental results showed that there was about 350% increase in flexural strength and 470% increase in tensile strength of the composites with respect to the neat polybenzoxazine, while, compressive properties were adversely affected. The composites exhibited an optimum increase of about 800% in flexural modulus and 200% in tensile modulus. Enhancing the fiber length, leads to fiber entanglement in the composites, resulted in increased plastic deformation at higher strain. Multiple branch matrix shear, debonded fibers and voids were the failures visualized in the microscopic analyses. Defibrillation has been exhibited by all composites irrespective of fiber length. Fiber debonding and breaking were associated with short fibers whereas clustering and defibrillation were the major failure modes in long fiber composites. Increasing fiber loading improved the tensile and flexural properties until 50–60 wt% of fiber whereas the compressive property consistently decreased on fiber loading. Copyright © 2008 John Wiley & Sons, Ltd.     

Mechanical properties of hybrid glass/sugar palm fibre reinforced unsaturated polyester composites

A research has been carried out to investigate the mechanical properties of composites made by hybridizing sugar palm fibre (Arenga pinnata) with glass fibre into an unsaturated polyester matrix. Hybrid composites of glass/sugar palm fibre were fabricated in different weight ratios of strand mat glass fibres: sugar palm fibres 4:0, 4:1, 4:2, 4:3, 4:4, and 0:4. The hybrid effects of glass and sugar palm fibre on tensile, flexural and impact properties of the composites were evaluated according to ASTM D5083, ASTM D790 and ASTM D256 respectively. Results have been established that properties of hybrid glass/sugar palm composites such as tensile strength, tensile modulus, elongation at break, toughness, flexural strength, flexural modulus and impact strength are a function of fibre content. The failure mechanism and the adhesion between fibres/matrix were studied by observing the scanning electron micrographs of impact fracture samples. In general, the incorporation of both fibres into unsaturated polyester matrix shows a regular trend of increase in the mechanical properties.     

Properties of glass-fiber reinforced composites based on liquid diglycidyl ether of bisphenol-c-epoxy resin

Glass-fiber reinforced epoxy composites were fabricated from the matrix resin liquid diglycidyl ether of bisphenol-C (DGEBC) using various amines as curing agents with and without fortifier (20 phr). The epoxy laminates were evaluated for their mechanical properties, such as flexural strength, interlaminar shear strength (ILSS), tensile strength and shore-D hardness. Dielectric properties, such as the dielectric constant, tan δ, dielectric loss and the resistivity of the laminated samples, were measured. The effect of the chemical reagents on the mechanical properties (i.e. flexural strength, lLSS) was also studied.     

等离子接枝处理的CF/PAA复合材料层间剪切强度及其形貌研究

采用等离子技术对碳纤维(CF)进行接枝芳基乙炔(PAA)处理,研究了影响CF／PAA复合材料层间剪切强度(ILSS)的因素。结果表明,经等离子接枝PAA处理后,复合材料的ILSS有了很大提高。SEM显示经接枝处理后CF和PAA树脂之间的界面结合紧密,改善了复合材料的界面结合性能。     

Continuous cellulose fiber-reinforced cellulose ester composites. II. Fiber surface modification and consolidation conditions

We prepared thermoplastic composite panels using solution impregnation of continuous lyocell (regenerated cellulose) fibers with a cellulose mixed-ester (cellulose acetate butyrate) matrix. We examined both fiber-matrix adhesion and melt consolidation in an effort to produce uniform panels having low void content and high mechanical strength. We characterized the effect of surface modification by acetylation on interfacial adhesion between the cellulose fiber and cellulose ester. Whereas wood fiber acetylation had previously been observed to result in significant strength gains in (discontinuous) wood fiber- reinforced composites (with the same matrix material), we did not observe a similar increase in strength in the continuous lyocell cellulose fiber system. This suggests that interfacial stress transfer is not a limitation in this system. This was confirmed by microscopic examination of the fracture surfaces, which indicated that fiber-matrix adhesion was considerable in the absence of fiber surface modification. We then systematically varied melt consolidation conditions (temperature, pressure and time) in an attempt to define optimum consolidation parameters by using design of experiments (DOE) methodology. We measured both interlaminar shear strength (ILSS) and composite void volume. We found that a minimal void content (ca. 2.83 vol. %) occurred at moderate temperatures (200°C), low consolidation pressures (81.4kPa) and long press times (13min). This was also where we maximized the interlaminar shear strength (ILSS) at a value of 16.3MPa. This agrees with the regression model predictions. We observed the highest tensile properties at the ILSS and void-volume optimal-consolidation condition: a tensile modulus of 22GPa and tensile strength of 246MPa were obtained.     

Thermal and mechanical properties of particulate fillers filled epoxy composites for electronic packaging application

Epoxy composites containing particulate fillers‐fused silica, glass powder, and mineral silica were investigated to be used as substrate materials in electronic packaging application. The content of fillers were varied between 0 and 40 vol%. The effects of the fillers on the thermal properties—thermal stability, thermal expansion and dynamic mechanical properties of the epoxy composites were studied, and it was found that fused silica, glass powder, and mineral silica increase the thermal stability and dynamic thermal mechanical properties and reduce the coefficient of thermal expansion (CTE). The lowest CTE value was observed at a fused silica content of 40 vol% for the epoxy composites, which was traced to the effect of its nature of low intrinsic CTE value of the fillers. The mechanical properties of the epoxy composites were determined in both flexural and single‐edge notch (SEN‐T) fracture toughness properties. Highest flexural strength, stiffness, and toughness values were observed at fillers content of 40 vol% for all the filled epoxy composites. Scanning electron microscopy (SEM) micrograph showed poor filler–matrix interaction in glass powder filled epoxy composites at 40 vol%. Copyright © 2007 John Wiley & Sons, Ltd.