加成型酚醛改性双马树脂及其复合材料性能

双马来酰亚胺(BMI)树脂因其优异的性能已在航空航天、电子和其他工业领域获得应用，为满足其在高速飞行器结构件中需求，用加成型酚醛树脂改性BMI体系以改善其热-力学性能。通过Williamson醚化反应合成了炔丙基醚化酚醛树脂(PN)和烯丙基醚化酚醛树脂(AN)，采用熔融共混法分别与N,N’-(4,4’-亚甲基二苯基)双马来酰亚胺(BDM)和2,2’-二烯丙基双酚A(DABPA)树脂体系(BD)共混，制备了三元热固性树脂：PN改性BD(BDPN)和AN改性BD(BDAN)。研究了两种加成型酚醛树脂改性的BD树脂体系的加工工艺性和固化行为的变化，并对改性前后固化树脂及其复合材料的热、力学性能进行了研究。结果表明：共混树脂体系都在极性溶剂中有好的溶解性，加工窗口都有50℃以上。BDPN和BDAN固化反应只有一个放热峰，最高放热峰值温度比BD树脂低。用FTIR跟踪验证了BD、BDPN和BDAN树脂体系发生的Ene、DielsAlder、Claisen重排和炔基与马来酰亚胺环的聚合反应。PN热氧稳定性好，改性的BDPN固化树脂空气中质量损失5wt%的温度(T_d5)高于400...

Properties of bismaleimide resin modified by addition-curing phenolic and their composites

Bismaleimide (BMI) resin has been widely used in aerospace, electronics and other industrial fields because of its excellent properties. In order to meet the needs of structural components for high-speed aircraft, the additional phenolic modifier is introduced to improve the thermo-mechanical properties of BMI resin. The propargyl etherified novolac (PN) and allyl etherified phenolic (AN) as an addition modifier were synthesized by Williamson etherification. The PN and AN were used to modify N, N'-(4, 4'-diphenylmethylane) bismaleimide (BDM)/2, 2'-diallyl bisphenol A (DABPA) resin system (BD) in melting mixing to obtain the ternary blended resins of BDPN and BDAN. The processability and cure reactions of the BDPN and BDAN were studied. The thermal property and mechanical property of the cured BD, BDPN and BDAN were further investigated. The results show that the ternary blended resins exhibit good solubility and meltability, and have an above 50℃ of process window. There is only a single exothermal peak in DSC curves of BDPN and BDAN. The peak temperatures of BDPN and BDAN are lower than that of BD. The Fourier transform infrared (FTIR) was used to monitor the curing reactions of BD, BDPN and BDAN resins. The reactions of Ene, Diels-Alder, Claisen rearrangement and addition of alkyne and maleimido group were detected during curing. The cured PN resin has good thermo-oxidative stability. The residual yield at 800℃ (Y_r800℃) of cured BD in air increases from 3.7% to 23.1% after the BD resin was modified with PN resin. The temperature of 5wt% mass loss (T_d5) of the cured BDPN in air is higher than 400℃. The limited oxygen index (LOI) of the cured BD, BDPN and BDAN resins are 30.2%, 32.5% and 31.0%, respectively. The cured resins are nonflammable. The impact strength and flexural modulus of the cured BD resin increase with addition of PN and AN resins. The impact strength and flexural modulus of the cured AN modified BD resin increase by 19% and 30% respec-tively. However, the flexural strength of the BDPN and BDAN resins decrease since the crosslinked density of the cured modified resins decline. The water absorption in boiling water of the cured BDPN and BDAN resins are lower than that of the cured BD resin, and decrease by 8.6% and 14% after 40 h. The flexural strength, flexural modulus and interlaminar shear strength (ILSS) of the T300 carbon fiber cloth (T300CF) reinforced BDAN composite (T300CF/BDAN) at room temperature are higher than that of the T300CF reinforced BD composite. The flexural strength of the T300CF/BDPN at 200℃ retains a 98.6% retention, reaches to 575 MPa. The propargyl etherified novolac can used to improve the heat properties of bismaleimide which is a new approach for modification of bismaleimides, and promising to be utilized in preparation of the structural components of composite with heat-resistance at 200℃.