【摘要】 采用TA-Q800动态热机械分析仪(DMA)研究了聚乙烯基对苯二甲酸二(对丁氧基苯)酯(PBPCS)纤维的形变回复性能,发现PBPCS纤维具有非常好的形状记忆效应,在145℃及以上温度,形状回复速率最好,9min左右可以从400%的伸长回复到原来的尺寸,于145℃,重复实验5次,结果说明形变回复重复性好.二维X衍射(2DX-Ray)研究显示形变前后PBPCS柱状分子直径d由2.54nm变为2.42nm,表明拉伸后PBPCS螺旋状的大分子主链处于更为伸直的构象,因此分子主链产生一定的内应力,即形变回复应力.由此可见,PBPCS相对柔性的聚乙烯主链使纤维具有良好的形变回复性能,而侧基的甲壳效应使得纤维能够保持初始尺寸,即PBPCS所具有的类似弹簧的特殊螺旋状分子结构是其纤维具有形状记忆效应的内在原因.更多还原

【Abstract】 The shape memory effect of poly2,5-bis[(4-butoxyphenyl)oxycarbonyl]-styrenes(PBPCS),one of the classical mesogen jacketed liquid crystal polymers(MJLCPs),fiber was studied by dynamic mechanical analysis(DMA).According to the results,the outstanding shape recovery ability of PBPCS fiber was found.The reversion rate of PBPCS fiber was improved with the increase of temperature apparently when it was above T_g(106.7℃).Especially when temperature above 145℃,the rate of shape recovery was the best.The time of recovery from 400% draw ratio to origin length was about 9 min.The repeatability of shape memory was good in 5 repeated times.2-Dimensional wide angle X-ray diffraction(2D WAXD)experiments showed the diameter of helical cylindrical blocks changed from 2.5 nm to 2.4 nm after deformation.This result indicated that the helical main-chain of PBPCS was in a more straight conformation.So,there would be a certain inner stress in the molecular chain,namely the shape memory force(F_ sm).It was about 1.6 MPa.There was no stable and memory phase structure of traditional shape memory polymers(SMP)in PBPCS because it was an amorphous polymer.The reason of PBPCS fiber with the shape memory effect is its special helical molecular chain structure just as a spring,say,the flexible polystyrene main chain makes PBPCS fiber present a good strain reversion ability,and the mesogenic effect of side chains makes the fiber keep its original dimension.更多还原