The shape memory effect of poly{2

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 Tg(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(Fsm).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.