沉淀法合成联苯基液晶环氧及强韧化体系制备

Synthesis of biphenyl liquid crystal epoxy by precipitation reaction and preparation of its strengthening and toughening system

摘要:

首先，以4,4-联苯二酚（BP）和环氧氯丙烷（ECH）为原料，通过“一步沉淀法”制备了高环氧值、高结晶度的4,4-联苯二酚二缩水甘油醚（DGEBP）；采用FTIR、NMR等手段对其结构进行表征，并确定了最佳工艺条件；POM和XRD等分析表明DGEBP是高结晶度环氧树脂，不具备液晶行为。选择六种固化剂分别固化DGEBP，制备了六种三维交联网络固化物，所得固化物均具有良好的热性能。其次，采用DGEBP改性双酚A环氧树脂/聚酚氧树脂（PKHH）二元共混树脂体系，以双氰胺（DICY）为固化剂，制备了多元改性体系（BPx-BA-PKHH）。POM和机械力学性能分析结果表明：固化体系中DGEBP单元表现出了液晶性，有液晶域出现；同时，BPx-BA-PKHH的拉伸强度（87.39 MPa）、模量（2.76 GPa）、剪切强度（19.38 MPa）和韧性都有明显提升。当DGEBP添加量为5~7份时体系综合性能最佳。

Abstract:

First, 4,4-biphenol diglycidyl ether (DGEBP) with high epoxy value and high crystallinity was prepared by one-step precipitation reaction of 4,4-biphenol (BP) and epichlorohydrin (ECH). The structure of DGEBP was confirmed by FTIR and NMR, and the optimum process conditions were determined successively. POM and XRD measurements verified that DGEBP was a solid powdered epoxy resin with high crystallinity and did not have liquid crystal behavior. Six curing agents were selected to cure DGEBP, respectively, to form crosslinked networks, and all the as-prepared cured products had good thermal properties. And then, DGEBP was used to modify bisphenol-A epoxy resin/polyoxyphenol (PKHH) binary blend resin system with dicyandiamide (DICY) as the hardener to obtain multiple modified ones (BPx-BA-PKHH). DMA and mechanical property analysis showed that DGEBP unit in the cured networks exhibiteds liquid crystallinity, and mesogenic domains appeared. At the same time, the tensile strength (87.39 MPa), Modulus (2.76GPa), shear strength (19.38 MPa) and toughness of BPx-BA-PKHH were significantly improved. And, the best comprehensive performance was obtained at the addition amount of DGEBP by 5-7 phr.