Abstract:

The properties of novolac resins (NR) are closely related to the cross-linked network structure of the cured material, and the applications in various fields place higher demands on the properties of NR. However, there is a contradiction between the improvement of NR's strength, glass transition temperature (T_g) and toughness, and improving NR's strength, toughness and T_g at the same time is still challenging. In this study, the modifier named BEP was prepared by the reaction of epoxy-based polyhedral oligomeric silsesquioxane (EPOSS) and biphenyl phenolic resin (BN). The BEP+NR co-curing network with an inhomogeneous cross-linked structure was established, which improved the strength and toughness of NR. On this basis, the curing kinetics of BEP+NR was studied. Dense inhomogeneous crosslinked networks were obtained by modulating the homopolymerization of BEP, the co-curing of BEP and NR, and the self-curing of NR. Compared to NR, the T_g, flexural strength and impact strength of 1BEP+NR up to 146.3℃, 4.1 kJ/m² and 76.5 MPa, which were improved by 10.9℃, 78.2% and 50.9%, respectively. With the homopolymerization degree of BEP increased, the inhomogeneous of the crosslinked network further increased and the mechanical properties, thermal stability and T_g of BEP+NR decreased.

Key words: phenolic resin, cross-linked network, polyhedral oligosiloxanes, kinetics, toughened

摘要：

热塑性酚醛树脂（NR）的性能与其交联网络结构密切相关，多领域应用对NR的性能提出了更高的要求，然而NR的强度、玻璃化转变温度（T_g）与韧性的提升存在着矛盾，同时提高NR的强度、韧性和T_g仍然面临着挑战。通过环氧基低聚倍半硅氧烷（EPOSS）和联苯酚醛树脂（BN）反应制备了改性剂BEP，与树脂构建了具有不均一交联结构的BEP+NR共固化网络，实现了树脂强度和韧性的提升，在此基础上对BEP+NR体系的固化特性进行了动力学研究，通过调控BEP的均聚、BEP和NR的共固化以及NR的固化得到了致密的不均一交联网络。1BEP+NR固化物的T_g、弯曲强度、冲击强度分别达到146.3℃、4.1 kJ/m²、76.5 MPa，相比NR分别提高10.9℃、78.2%、50.9%。随着BEP均聚程度的增加，交联网络的不均一性进一步增加，BEP+NR的力学性能、热稳定性和T_g降低。

关键词: 酚醛树脂, 交联网络, 倍半硅氧烷, 动力学, 增韧