Su Qiong, Wang Hongling, Wang Yanbin, Liang Shuang, Pang Shaofeng, Zhao Xiangfei, Sun Xiyang, Shi Xiaoqin, Zhao Jun
School of Chemical Engineering, Northwest Minzu University, Lanzhou 730030, China.
Key Laboratory of Environment-Friendly Composite Materials of the State Ethnic Affairs Commission, Lanzhou 730030, China.
Materials (Basel). 2023 Jan 19;16(3):952. doi: 10.3390/ma16030952.
Foamed materials based on a biopolymer of crop straws are environmentally friendly, but ignitability limits their application. In this study, two nitrogenous layers were introduced onto corn straw by esterification and grafting for flame-retardant purposes. The inner thin nitrogenous layer consisted of imidazole rings, and the outer thick nitrogenous layer consisted of grafted acrylamide by a free-radical polymerization. The outer nitrogenous layer was simultaneously introduced into the system with a foaming process at 150 °C. Azodiisobutyronitrile acted both as initiator of the polymerization and the main foaming agent, and deionized water acted both as a plasticizing agent and an auxiliary foaming agent, which simplified the process and formula. It was found that cavities of two different sizes were formed. The nonuniformity of the foamed material was ascribed to the heterogeneous foaming precursor consisting of a rigid core and a soft shell. Its excellent flame-retard rating of UL-94 V-0 was ascribed to the two nitrogenous layers, which provides a sufficient nitrogen source for non-combustible gases. A relatively high compression strength of 17.7 MPa was partly due to the fiber of corn straw.
基于农作物秸秆生物聚合物的泡沫材料环保，但可燃性限制了它们的应用。在本研究中，通过酯化和接枝在玉米秸秆上引入两层含氮层以达到阻燃目的。内层薄含氮层由咪唑环组成，外层厚含氮层由通过自由基聚合接枝的丙烯酰胺组成。外层含氮层在150℃的发泡过程中同时引入体系。偶氮二异丁腈既作为聚合引发剂又作为主要发泡剂，去离子水既作为增塑剂又作为辅助发泡剂，这简化了工艺和配方。发现形成了两种不同尺寸的孔洞。泡沫材料的不均匀性归因于由刚性核心和软壳组成的非均相发泡前驱体。其优异的UL-94 V-0阻燃等级归因于两层含氮层，它们为不可燃气体提供了充足的氮源。相对较高的17.7MPa压缩强度部分归因于玉米秸秆纤维。
