摘要
聚氨酯弹性体（ＰＵ）是两相结构聚合物，软段相可能存在α型和β型球晶，硬段相可能存在三种类型球晶，即Ⅰ，Ⅱ，Ⅲ型。ＰＵ软段的Ｍ_ｎ在２０００以上，硬段中二苯甲烷－４，４＇－二异氰酸酯的含量为２～４ｍｏｌ时才可能在各自相中分别产生结晶。随聚合反应时间和室温老化时间的延长，结晶数量增加。ＰＵ结晶度高。球晶尺寸小，可提高ＰＵ的初始模量、杨氏模量、拉伸强度和韧性，能使伸长率下降。
Polyurethane(PU)elastomer possesses two-phase structure in which type αand type βspherulites may occur in the soft segment phase,and three types of spherulites,typeⅠ,typeⅡand typeⅢ,may occur in hard segment phase.The crystallization may be produced in soft and hard segment phase respectively only when the M_n in soft segment is above 2000,or the content of diphenylmethane-4,4'-diisocyanate in hard segment is no less than 2.The quantity of crystallization increases with the increase of polymerization time and aging time at room temperature.High crystallinity and small dimension of spherulite can increase the initial medulus,Young's modulus,tensile strength and toughness of PU,but ultimate elongation decreases.
出处
《合成橡胶工业》
CAS
CSCD
北大核心
1994年第6期376-379,共4页
China Synthetic Rubber Industry
关键词
聚氨酯
弹性体
结晶行为
结构
polyurethane
elastomer
crystal behavior
relation between structure and property
review
