苯并噁嗪树脂/丁腈橡胶复合材料双网络结构及其耐烧蚀和绝热性能

考察了苯并噁嗪树脂（PBR）对丁腈橡胶（NBR）耐烧蚀和绝热性能的影响。结果表明，随着PBR用量的增加，PBR/NBR复合材料的线性烧蚀率和热导率下降，这主要是由于燃烧表面的炭化物和基质之间的强烈相互作用及PBR在整个NBR基体中形成的树脂网络结构阻止了外部热流的侵入，此外PBR还能生成不可燃气体阻止了基质的进一步燃烧。当PBR用量为60份（质量）时，PBR/NBR复合材料的线性烧蚀率和热导率分别达到0.023 mm/s和0.169 W/（m·K）。

Dual network of poly-benzoxazine /nitrile rubber composite and its ablation resistance and thermal insulation properties

Poly-benzoxazine resin (PBR) with a unique N, O six-membered heterocyclic structure, had a potential application in the field of aerospace due to its low expansion coefficient, high weather resistance, high carbon yield, good mechanical strength, and excellent ablation resistance［1］. In this work, PBR was incorporated into nitrile rubber (NBR) to obtain PBR/NBR composites, and the ablation resistance and thermal insulation of the PBR/NBR composites were investigated. The formulation of rubber compounds was NBR 100 phr (mass, the same below), 4010 NA 2.0 phr, zinc oxide 2.0 phr, SA 2.4 phr, CZ 2.2 phr, sulfur 1 phr and PBR varies. And the samples were named as P X/NBR, where X stood for the amount of PBR.　　　　As shown in Fig 1(a), with the increasing amount of PBR, the linear ablation rate and thermal conductivity of PBR/NBR nanocomposites decreased. The linear ablation rate and thermal conductivity of PBR/NBR nanocomposites with 60 phr PBR arrived at 0.023 mm/s and 0.169 W/(m·K), respectively, suggesting PBR was a thermally stable and char-producing polymeric material［2］. Compared to NBR [as shown in Fig 1(b)], a relatively dense char layer was found on the surface of PBR/NBR [as shown in Fig 1(c)], indicating that the formation of more dense char layer on the ablated surface had significant ablation resistance. Char retention on the substrate surface after being subjected to high impact force of oxy-acetylene flame further validated the strong interaction between char and substrate as well as the resin network formation throughout the NBR matrix, thereby effectively preventing the intrusion of external heat flow during the ablation period and avoiding high heat transfer to the internal structure and reducing the ablation rate［3］. Moreover, the non-flammability gas induced by the degradation of the benzoxazine resin tended to reduce the concentration of the O2 and the temperature of the surface［4］. The new ablation and thermal resistant materials had potential applications in aerospace fields.