丁苯、丁腈基聚氨酯的形态与性能

用示差扫描量热法 (DSC)、红外分光光度计 (FTIR)和原子力显微镜 (AFM)研究了端羟基聚丁二烯 苯乙烯共聚物 (HTBS)、端羟基聚丁二烯 丙烯腈共聚物 (HTBN)和端羟基聚丁二烯 (HTPB)与甲苯二异氰酸酯、1 ,4 丁二醇构成的溶液法聚二烯烃基聚氨酯 (PU)的形态结构 .结果表明HTPB和HTBS基PU的相分离程度很大 ,而HTBN基PU的相分离程度小 .这可能归因于HTBS软段的极性低 ,不能与硬段形成氢键 ,而HTBN软段中的腈基具有很强的极性 ,且可以与硬段形成氢键作用 ,增加了软硬段间的相容性 ,相分离程度明显降低 .AFM表明HTBN PU随着硬段含量提高 ,表面粗糙度增大 ,由软段为连续相逐渐过渡到双连续结构 .在硬段含量 6 3%时 ,HTBN和HTPB基PU均呈双连续结构 ,而HTBS PU中硬段为连续相 .HTBN PU软段的相区尺寸在1 2nm左右 ,表面粗糙度较大 ,HPBS PU软段的相区尺寸在 1 1nm左右 ,表面粗糙度最小 ,HTPB PU存在 1 4nm和 5 0nm大小不等的软段相区尺寸 .力学性能表明 ,在软段中引入苯乙烯和丙烯腈结构 ,可使聚氨酯抗张强度分别提高 1 5和 2倍 ,模量和断裂伸长率也明显提高

MORPHOLOGY AND PROPERTIES OF POLYBUTADIENE/STYRENE,POLYBUTADIENE/ACRYLONITRILE BASED POLYURETHANE

Polyurethane membranes based on toluene diisocyanate (TDI),1,4-butanediol (BDO) and hydroxyl terminated polybutadiene/styrene (HTBS) or hydroxyl terminated polybutadiene/acrylonitrile (HTBN) and hydroxyl-terminated polybutadiene (HTPB) were synthesized by solution polymerization.The morphologies of these samples were characterized by DSC,FTIR and AFM measurements.DSC results showed that the T g of the soft segments for HTPB and HTBS were about only 3～6℃ higher than that of their pure soft segments.This indicated that the HTPB and HTBS based PU were well phase separated.The T g of soft segments for HTBN,however,were about 11～15℃ higher than that of the pure soft segment,which revealed a lower microphase separation degree of HTBN based PU.This might be attributed to that the —CN groups in the soft segment could create hydrogen bonding with —NH groups in hard segment as proton receiver leading to partly mixing of soft and hard segment.Results of infrared analysis revealed that about 90 percent of urethane CO groups formed hydrogen bonds between hard segments for both HTPB and HTBS based PU and about 84 percent for HTBN based PU.AFM results showed that the coarseness degree increased with increasing the hard segments content in HTBN based PU.HTBN and HTPB based PU showed two continuous phases when hard segment content reached 63%,whereas hard segments formed the only continuous phase in HTBS with the same hard segment content.The mechanical properties showed that the strength of HTBS and HTBN based PU were about 1.5 and 2 times higher than that of HTPB based PU respectively.The modulus and elongation of HTBN and HTBS based PU was also higher than that of HTPB based PU.