Department Wood Science & Technology, School of Engineering, Zhejiang A&F University, Hangzhou 311300, China.
Department Wood Science & Technology, School of Engineering, Zhejiang A&F University, Hangzhou 311300, China.
Int J Biol Macromol. 2020 May 1;150:786-792. doi: 10.1016/j.ijbiomac.2020.02.059. Epub 2020 Feb 19.
Lignin, which is crosslinked by ether and carbon‑carbon linkages, is a highly branched polymer consisting of phenyl propane units. And owing to the abundant phenolic hydroxyl groups and its structural heterogeneous characteristics, lignosulfonate, considered as a renewable aromatic macropolymer, can be used as co-curing agent in EP thermoset systems. In this study, kinetics of lignosulfonate (LS) and partially depolymerized lignosulfonate (DLS) as co-curing agents for applications to EP thermoset were discussed with the differential scanning calorimetry (DSC) measurement. The activation energy (E) and dynamic modeling of curing reaction were obtained by the methods of non-isothermal kinetic analysis reported by Kissinger and Ozawa. The glass transition temperature (T) was determined by DSC and mechanical properties of epoxy resins were carried out using the Universal Testing Machine. The LS dropped the exothermic peak temperature and E of curing reaction of EP thermoset. Those of DLS were more active than the higher molecular weight lignosulfonate. The EP thermoset cured with DLS (EP-DLS) exhibited much higher reactivity, and the curing reaction could be occurred at lower temperature. The T of EP-DLS has risen by 10 °C compared with the case without lignosulfonate. The tensile strength, elongation at break and impact strength of EP-DLS rose by 28.7%, 52.5% and 53.5%, respectively, than those of the epoxy resin cured with LS (EP-LS).Molecular weight of lignosulfonate could be an important factor of the curing reaction of EP thermoset. The high performance EP thermoset could be obtained by partially depolymerized lignin as co-curing agents.
木质素是一种由苯丙烷单元组成的高度支化聚合物，通过醚键和碳-碳键交联。由于其丰富的酚羟基和结构不均匀的特点，木质素磺酸盐被认为是一种可再生的芳香族大分子聚合物，可用作 EP 热固性体系的共固化剂。在这项研究中，通过差示扫描量热法（DSC）测量，讨论了木质素磺酸盐（LS）和部分解聚木质素磺酸盐（DLS）作为共固化剂应用于 EP 热固性体系的动力学。通过 Kissinger 和 Ozawa 报道的非等温热力学分析方法，获得了固化反应的活化能（E）和动力学模型。通过 DSC 确定玻璃化转变温度（T），并使用万能试验机测试环氧树脂的力学性能。LS 降低了 EP 热固性体系的固化放热峰温度和 E。DLS 的 E 比高分子量木质素磺酸盐更低。用 DLS 固化的 EP（EP-DLS）表现出更高的反应性，固化反应可以在更低的温度下进行。与没有木质素磺酸盐的情况相比，EP-DLS 的 T 上升了 10°C。EP-DLS 的拉伸强度、断裂伸长率和冲击强度分别比用 LS 固化的环氧树脂（EP-LS）提高了 28.7%、52.5%和 53.5%。木质素磺酸盐的分子量可能是 EP 热固性体系固化反应的一个重要因素。用部分解聚木质素作为共固化剂可以得到高性能的 EP 热固性体系。
