TRIPLE-SHAPE MEMORY BEHAVIOR OF PHENOXY MODIFY EPOXY/POLYCAPROLACTONE BLENDS

摘要

Multi-shape memory polymers (SMPs), which are capable for fixing more than one temporary shape and recovering sequentially from one temporary shape to another which eventually to the permanent shape, have attracted increasing attention. Triple-shape memory amine cured epoxy (EP)/polycaprolactone (PCL) blends modified with phenoxy were prepared in this study to improve the critical drawback of EP/PCL blends which exhibited not overall excellent shape memory performance, recover ratio and fixity ratio. An attempt was made to achieve better shape memory (SM) behavior by a hydrogen bonding interaction between the PCL carbonyl group and the phenoxy hydroxyl group. PCL and phenoxy are miscible in the amorphous state. Forming the hydrogen bonding may increase the amount of hard segments and enlarge the stored force to recover to the permanent shape. Moreover, phenoxv also react with epoxide of EP, enhancing the amount of hard segment in the cross-linked network. We keep mass ratio of EP/amine and PCL as 3 to 1 in all specimens and adjust concentrations of phenoxy as 0%, 1%, 5% and 10 wt% in all blends. To set the two temporary shapes, the glass transition temperature (Tg) of 32°C of the EP and the melting temperature (Tm) of 58°C of PCL were served during the SM cycle. These transition temperatures are easy to reach for the real application. Dynamic Mechanical Analysis (DMA) was used to determine the SM properties in tensile loading. Results on the co-continuous and polvmerization induced phase separation (PIPS) structures was demonstrated from optical microscope (OM). Results show that with phenoxy adding can increase the recovery ratio of PCL part to 97% and EP part. At the same time, keeping the fixity ratio above 98%.