RTM改性苯并噁嗪树脂及复合材料性能研究

研究了RTM改性苯并噁嗪树脂及复合材料性能.用DMA研究RTM改性苯并噁嗪树脂体系的储能模量、损耗模量和玻璃化转变温度;用流变仪研究黏度特性;用TGA和TGA微分曲线研究热分解性能;并研究了RTM改性苯并噁嗪树脂及复合材料的力学性能.结果表明:RTM改性苯并噁嗪树脂体系的玻璃化转变温度是206℃;至少有400min的低黏度(η≤0.5Pa.s)时间作为工艺开放期;在氮气气氛下,RTM苯并噁嗪树脂体系热失重分两个主要阶段,在375℃时发生5％热失重,800℃残碳率是45.2％;RTM苯并噁嗪树脂基体拉伸强度72.4MPa,拉伸模量5.07GPa,弯曲强度173MPa,弯曲模量4.6GPa;碳纤维增强RTM苯并噁嗪树脂基复合材料的常规力学性能优异.     

苯并噁嗪树脂流变特性及工艺窗口预报研究

苯并噁嗪树脂是一种适宜RTM工艺的新型耐烧蚀开环聚合酚醛树脂,本工作对该树脂的流变特性进行研究.在粘度实验和DSC热分析实验的基础上,依据双阿累尼乌斯方程建立了与实验数据较为吻合的化学流变模型.模型可揭示树脂在不同工艺条件下的粘度变化规律,定量预报树脂的低粘度平台工艺窗口,为该树脂RTM工艺窗口的确定以及RTM工艺参数优化提供了的科学依据.     

用于RTM 成型工艺的苯并口恶嗪树脂及其复合材料

以苯酚、苯胺和甲醛为原料, 合成了三种不同结构的低粘度苯并口恶嗪中间体树脂。根据RTM 成型工艺中注塑和成型过程对基体树脂的特殊要求和不同组分的反应活性, 系统研究了树脂粘度和凝胶化时间与温度的关系, 及玻璃布层压板的力学性能和耐热性, 详细讨论了树脂组成和催化剂种类及用量的影响。结果表明, 以有机酸或环氧-叔胺为催化剂, 以低粘度苯并口恶嗪树脂为主体所构成的多组分树脂体系, 是一类可用于RTM 成型工艺的新型树脂; 该类树脂基复合材料可用做耐高温结构材料在155℃长期使用。      

高性能苯并(噁)嗪基复合材料研究进展

综述了近年来国内外在苯并(噁)嗪树脂基复合材料方面的研究进展,重点介绍了以苯并(噁)嗪为基体的复合材料在耐热、增韧、增强等方面包括化学改性和物理共混研究进展,并初步判断了今后以苯并(噁)嗪树脂为基体的复合材料的发展方向.     

一种RTM 用苯并噁嗪树脂的工艺性及其复合材料性能

制备了一种可用于树脂传递模塑( RTM) 工艺的高性能苯并噁嗪共混树脂体系( BA21) 。研究了BA21 的注射工艺性, 确定了其固化程序, 并考察了采用RTM 工艺制备的BA21 基复合材料的基本力学性能。升温及恒温黏度测试结果表明, BA21 树脂体系能够用于RTM 工艺。依据修正的双阿累尼乌斯方程建立了与实验数据较为吻合的化学流变模型, 利用该模型可以选择合适的注射温度。通过不同温度下的恒温DSC 测试及修正的Kamal 动力学模型计算得到BA21 树脂体系的固化反应级数, 并确定后固化温度为200 ℃。采用RTM 工艺制得的玻璃纤维/ BA21 复合材料表现出优异的力学性能, 弯曲强度达600 MPa , 弯曲模量达30 GPa , 冲击强度达210 kJ/ m2 。      

低黏度抗烧蚀RTM用苯并噁嗪树脂及其复合材料性能研究

针对复合材料构件的力热性能和成型工艺要求,研究了用于RTM成型的低黏度抗烧蚀苯并噁嗪树脂体系及其复合材料性能。变温黏温和等温黏温测试结果表明,苯并噁嗪树脂在90℃起始黏度低于600mPa·s, 8h保温后黏度低于800mPa·s,可以满足RTM工艺灌注要求。同时,苯并噁嗪树脂在70～120℃范围内具有适宜的黏度,在100℃和110℃下的注胶工艺开放期均大于8h。在氮气氛围下,该苯并噁嗪树脂体系热失重分两个阶段,在281℃发生5%热失重,800℃残炭率为51.3%,表明其具有良好的抗烧蚀性能。通过DMA分析,RTM成型碳纤维/苯并噁嗪树脂复合材料的T_g为277℃,具有良好的耐高温性能。采用RTM工艺制得的碳纤维/苯并噁嗪树脂复合材料表现出良好的力学性能,室温层间剪切强度达65.5MPa, 150℃拉伸性能保留率达99%以上,压缩、弯曲性能保留率达70%以上,层剪性能保留率也达63%。     

碳纤维/SiO2/聚苯并(噁)嗪复合材料的制备及性能研究

以纳米SiO2/聚苯并(噁)嗪(PBOZ)为基体树脂,与碳纤维(CF)复合,制备了CF/SiO2/PBOZ复合材料,研究了纳米SiO2含量对其弯曲强度、层间剪切强度以及断面形貌的影响.结果表明,纳米SiO2含量为4%时,CF/SiO2/PBOZ复合材料的性能最好,材料的弯曲强度和层间剪切强度分别达到835和72.1MP...     

新型含炔基苯并(口恶)嗪的合成及性能研究

为了提高苯并(口恶)嗪的热稳定性,以对碘苯胺、3-氨基苯乙炔、苯酚及多聚甲醛为原料合成了新型的含炔基苯并(口恶)嗪(PA-an-ba),并通过傅里叶变换红外光谱仪和核磁共振仪(~1 H-NMR,~(13) C-NMR)对其结构进行表征,通过差示扫描量热仪和热重分析仪对其固化行为和热性能进行了测试。结果表明:炔基的引入能显著提高聚苯并(口恶)嗪的耐热性,其失重率为5%和10%时的温度分别为437℃和464℃,800℃的残炭率为73%,比传统苯并(口恶)嗪提高了40%。     

苯并噁嗪树脂的应用研究进展

针对苯并噁嗪树脂的工业应用,综述了近年来苯并噁嗪树脂的单体合成、树脂改性及固化研究的现状.     

Electrical properties of short sisal fiber reinforced polyester composites fabricated by resin transfer molding

The electrical properties of sisal fiber reinforced polyester composites fabricated by resin transfer molding (RTM) have been studied with special reference to fiber loading, frequency and temperature. The dielectric constant (ε′), loss factor (ε″), dissipation factor (tan δ) and conductivity increases with fiber content for the entire range of frequencies. The values are high for the composites having fiber content of 50 vol.%. This increment is high at low frequencies, low at medium frequencies, and very small at high frequencies. The volume resistivity varies with fiber loading at lower frequency and merges together at higher frequency. When temperature increases the dielectric constant values increases followed by a decrease after the glass transition temperature. This variation depends upon the fiber content. Finally an attempt is made to correlate the experimental value of the dielectric constant with theoretical predictions.     

Numerical study of resin transfer molding (RTM) curing process

It is a very important phase in resin transfer molding (RTM) process that resin is cured. The result of the curing process determines the quality of a part, including mechanical properties, lifecycle of the part under high temperature and chemical properties. Therefore, it is very meaningful to discuss the curing process. In our work, the code is prepared based on unstructured mesh using divergence theorem. A case is used to verify properness of the code and the results are in good agreement with the published experiment data. In the paper, some factors of materials and numerical calculation, e.g., time step, reaction heat, the whole heat conductivity of fiber and resin and fiber initial temperature, which affect result of simulation, are emphatically investigated and carefully revealed. The conclusion shows that time step, the reaction heat and heat conductivity have an important effect on the curing process, while fiber initial temperature has very little impact. These are helpful to understand and adopt the curing process in order to produce good products.     

玄武岩增强硼酚醛树脂基复合材料工艺性能研究

利用正交试验方法,讨论冷却方式、成型压力、增强纤维百分含量、成型温度对玄武岩增强硼酚醛树脂基复合材料拉伸强度和弯曲强度的影响.结果表明:复合材料中增强纤维百分含量对其力学性能影响最大,成型压力增大有利于复合材料力学性能的改善,成型温度对基体材料的结构有较大影响,当成型温度较高时,复合材料具有较大的弯曲强度,延长冷却时间有利于复合材料力学性能的提高.     

镀金属炭毡/树脂复合材料的电磁屏蔽性能

采用镀金属炭毡与环氧树脂、聚丙烯（PP）、ABS、聚苯乙烯（PS）、聚乙烯（PE）复合制备电磁屏蔽（EMS）复合材料,镀金属炭毡复合材料在1－1000MHz范围内的屏蔽效率可达40dB以上,不同的树脂体系对复合材料的屏蔽效率无显著影响,在炭毡纤维表面镀不同的金属对复合材料的屏蔽效率有较大的影响。     

Monitoring of resin flow in the resin transfer molding (RTM) process using point-voltage sensors

Multiple point-voltage sensors were used to monitor the mold filling stage of the resin transfer molding (RTM) process. Both lineal- and point-voltage sensors are electrical circuits in which the two poles of the sensor are closed when liquid thermoset resin arrives at the sensor location in the mold cavity. The electrical conductance of the liquid resin causes an increase in the output voltage, V_sens of the circuit. Although the gradually varying in situ data of a lineal sensor is more informative than a point-voltage sensor, lineal-voltage sensors might mislead the user if the resin covers the wires at multiple sections, or if the resin covers the wires starting from an unexpected section. Two kinds of sensors were developed: a set of similar, wrapped and compact lineal-voltage sensors acting as point-voltage sensors; and a point-voltage sensor with voltage amplification. Without this amplification, the increase in V_sens might be difficult to detect if the resin system has a low electrical conductivity and there is noise in the DAQ system. The accuracy and reliability of the new sensor system was verified by comparing the in situ sensor data with the visually recorded resin flow.     

碳纤维/环氧树脂复合材料高速冲击性能

采用树脂传递模塑(RTM)工艺制备碳纤维/环氧树脂复合材料,通过空气炮冲击实验研究树脂韧性和碳纤维类型对复合材料抗高速冲击性能的影响,并对高速冲击后的试样进行压缩性能测试,研究高速冲击损伤对复合材料剩余压缩性能的影响。结果表明:树脂的韧性可以降低复合材料遭受高速冲击时的内部损伤程度,大幅提高复合材料的抗高速冲击性能和冲击后剩余压缩性能;T700S碳纤维增强复合材料抗高速冲击性能优于T800H碳纤维增强复合材料;复合材料的破坏模式与冲击速率有关,冲击速率较低时,复合材料弹击面出现圆形凹坑,背弹面出现鼓包;冲击速率较高时,复合材料弹击面出现圆形通孔,背弹面出现沿纤维方向撕裂断口。     

碳纤维/双马树脂复合材料抗高速冲击性能

采用热压罐成型工艺制备碳纤维/双马树脂复合材料,并采用空气炮冲击装置、超声水浸C扫描探伤装置和万能材料试验机等测试手段,研究碳纤维类型和碳纤维体积分数对复合材料层板抗高速冲击性能的影响.结果表明:与CCF300碳纤维、CCF700碳纤维和CCF800H碳纤维相比,TZ1000G碳纤维复合材料抗高速冲击性能最优;碳纤维体积分数越高,复合材料层板抗高冲击性能越高;碳纤维复合材料的破坏模式与冲击速率有关,冲击速率较低时,复合材料层板弹击面出现周围含纤维分层开裂的圆形凹坑,背弹面出现沿纤维方向的分层开裂;冲击速率较高时,复合材料层板弹击面出现周围含纤维分层开裂的圆形通孔,背弹面出现撕裂断口.     

羟基硅油改性酚醛树脂基碳纤维复合材料特性研究

利用FT-IR、SEM、拉伸试验等测试方法分析了羟基硅油改性酚醛树脂基碳纤维复合材料机理，并对羟基硅油改性酚醛树脂基碳纤维复合材料特性进行了研究。实验结果表明：羟基硅油能有效改善界面结合状态，提高酚醛树脂基碳纤维复合材料的拉伸强度，为合理调整原料配比，控制生产工艺参数，获得综合性能优异的复合材料奠定了基础。     

Effect of rapid curing process on the properties of carbon fiber/epoxy composite fabricated using vacuum assisted resin infusion molding

Long processing cycle makes vacuum assisted resin infusion molding (VARIM) only suitable for low and medium volumes of production, and shortening of curing time is critical to improving the processing efficiency of automotive composite parts. In this paper, unidirectional carbon fiber reinforced composite laminates were fabricated by VARIM. Three different processes (namely quick, quick-post and preheating) were employed, in which a kind of rapid curing epoxy resin is used. The preheating of mold and fiber was conducted to shorten the filling time compared with that of quick process. Quick-post process with a post cure stage was investigated to verify the composite properties fabricated by quick process. The cycle time was 16 min for preheating process, about 30% shorter than that of quick process, simultaneously, flexural strength and interlaminar shear strength (ILSS) were respectively improved by 29% and 7% compared with those of quick process. The non-uniformity of mechanical properties at different positions along resin flow direction under preheating process was found, but the processing quality of composite was good. The preheating process is confirmed to be suitable for the improvement of processing efficiency of VARIM with good mechanical properties. In addition, the composite fabricated by quick-post process has better mechanical properties, which is attributed to the alleviation of residual stress during post curing process.     

Investigation on the spring-in phenomenon of carbon nanofiber-glass fiber/polyester composites manufactured with vacuum assisted resin transfer molding

Process-induced residual stress arises in polymer composites as a result of mismatched resin contraction and fiber contraction during the cure stage. When a curved shell-like composite part is de-molded, the residual stress causes the spring-in phenomenon, in which the enclosed angle of the part becomes smaller than the angle of its mold. In this paper, a new approach is presented to control and reduce the spring-in angle by infusing a small amount of carbon nanofibers (CNFs) together with liquid resin into the glass fiber preform using vacuum assisted resin transfer molding (VARTM) process. The experimental results showed that the spring-in angles of the L-shaped composite specimens were effectively restrained by the CNFs. An analytical model and a 3-D FEA model were developed to predict the spring-in phenomenon and to understand the role of CNFs in reducing the spring-in angle. The models agreed with the experimental results reasonably well. Furthermore, the analytical model explains how the CNF-enhanced dimensional tolerance control is accomplished through the reductions in the matrix’s equivalent coefficient of thermal expansion and linear crosslinking shrinkage.