Influence of molecular weight on thermal and mechanical properties of bisphenol A-based phthalonitrile resins
Influence of molecular weight on thermal and mechanical properties of bisphenol A-based phthalonitrile resins
复制标题
DOI：
10.1002/app.51783
复制
发表时间：
2021-10-20
影响因子：
3
通讯作者：
Laskoski, Matthew
中科院分区：
文献类型：
--
作者：
Butler, Tristan;Bunton, Caleb;Laskoski, Matthew
这项工作评估了化学结构和性能之间的相关性--交联型热固性树脂的基本热、机械和长期稳定性特性。以双酚A为基础的聚醚醚酮(PEEK)类低聚邻苯二甲腈(BISA)为原料，制备了不同相对分子质量的树脂。用差示扫描量热法研究了BISA树脂的固化热力学，结果表明，BISA树脂的低聚物相对分子质量的增加与熔点和固化起始条件呈正相关。用热重分析(TGA)对热性能的表征表明，分子量趋势相似，成炭率在57%到73%之间。不同相对分子质量的BISA的流变学研究表明，由较高相对分子质量的低聚物交联的邻苯二甲腈的粘度显著增加。此外，n=1链长树脂的凝胶点比n=25低聚物低100℃。硬度分析表明，n=1齐聚物交联的树脂最脆，而n=4BISA制备的热固性树脂的硬度最高。固化邻苯二甲腈的老化表明，n=10在长时间高温环境中保持最稳定。这项研究表明，使用不同分子量的低聚物制备BISA热固性是一种有效的改善韧性的策略，尽管代价是较低的热稳定性。
This effort assesses the correlation between chemical structures and performance-essential thermal, mechanical, and long-term stability properties of cross-linked thermosets. Resins of different molecular weights were prepared from the Bisphenol A based PEEK (TM)-like oligomeric phthalonitrile (BisA). Differential scanning calorimetry, which was used to investigate curing thermodynamics, indicated that BisA resins demonstrated positive correlation between increasing oligomer molecular weight and both resulting melting points and cure initiation conditions. Characterization of thermal properties using thermogravimetric analysis (TGA) indicated a similar molecular weight trend, with char yields ranging between 57% and 73%. Rheological studies of BisA of different molecular weights indicated significant viscosity increases in phthalonitriles that cross-linked from oligomers with higher molecular weights. Moreover, the n = 1 chain length resin exhibited a gel point at 100 degrees C lower than the n = 25 oligomer. Analysis of hardness of these cured polymers indicated that the resin cross-linked using the n = 1 oligomer was most brittle, while the thermoset derived from the n = 4 BisA demonstrated highest hardness. Aging of cured phthalonitriles indicated that the n = 10 remained most stable in long-duration high-temperature environments. This study suggests the use of preparing BisA thermosets from oligomers with different molecular weights as an effective strategy for improving toughness, albeit at the tradeoff of lower thermal stabilities.