嵌段聚酯型聚脲氨酯弹性体的热转变研究

用示差扫描量热法(DSC)研究了基于二苯基甲烷二异氰酸酯(MDI)、乙二胺(ED)和聚己二酸丁二醇酯(PBA)(M.W.1975和M.W.1228)两系列嵌段聚酯型聚脲氨酯(PUU)弹性体,并考察了这些材料在不同退火条件下软段结晶的热变化。结果表明:在这些弹性体中,PBA 1975系列具有比PBA1228系列更低的软段玻璃化温度,说明前者的相分离较好.软段T_(gs)和硬段T_(gh)对硬段含量的变化不敏感.退火样品的DSC结果表明:软段结晶具有两个吸热峰,提出在软段相中存在两种晶型(P_l和P_h)的假设,分析了两种晶型产生的原因.

STUDIES ON THERMAL TRANSITIONS OF SEGMENTED POLYESTER POLYURETHANEUREA ELASTOMERS

Studies on two series of segmented polyester polyurethaneurea (PUU) elastomers based on 4,4-diphenylmethane diisocyanate(MDI), ethylene diamine(ED) and polybutylene adipate (PBA)(M. W. 1975 and M. W. 1228) were made by DSC. Further, thermal changes of soft segment crystalline of these materials at different annealing conditions were also investigated. The results showed that in both series, PBA 1975 series had a lower T, of soft segment phase than PBA 1228 series, indicating that the phase segregation of the former was better, Both the soft segment Tg, and the hard segment T gh were not sensitive to the changes of the hard segment contents in the samples. The results on the annealed samples showed that soft segment crystalline melting existed in two peaks. The hypothesis of the existence of two types of crystallines (P1 and Ph) in the soft segment phase was proposed, and the reason that these two types of crystallines formed was analyzed theoretically.