Synthesis And Characterization Of Shape Memory Polyetherimides

Shape memory polymers are playing a more and more important role in modern society, particularly in aerospace field. Because of its high temperature resistence, radiation resistence and excellent mechanical properties, polyimide has been widely used in aerospace, electrical and other fields. In this experiment, diamine and dianhydride monomers with flexible group of ether, were used to prepare a new series of thermosetting and thermoplastic Shape Memory Polyetherimide and their shape memory property, thermal and mechanical properties ect, were studied.First, Membranes of Shape Memory thermoplastic were synthesised and were characterized by Infrared Spectroscopy, Thermogravimetric Analysis, Dynamic Mechanical Analysis, test of shape memory and dissolution. Results showed that the glass transition temperature Tg is above200℃; the decomposition temperature above490℃; shape fixed rate above96%; the time of shape recovery less than30s. Multipe shape memory performance cycle test were conducted and it tured out that shape memory performance was not significantly degradated.Membranes of Shape Memory thermosetting Polyetherimides with different content of crosslinking agent were also prepared and the effects of different content of three amino crosslinking agent on Shape Memory thermosetting Polyetherimide were explored. Results indicated that with the increase of the content of three amino crosslinking agent, the thermal and mechanical properties were getting better but with a smll extent and thus were less affected by the content of crosslinking agent; Compared with Shape Memory thermoplastic Polyetherimides, the glass transition temperature of the thermosetting Polyetherimides was higher by around7～11℃and the decomposition temperature and thermal and dynamic performance of Shape Memory thermosetting Polyetherimide was better but the time of shape recovery was slightly longer.At last, based on the theory of free volume and segment motion, the shape memory mechanism of Shape Memory Polyetherimide was analyzed and the theoretical explanation of the difference in shape memory performance between Shape Memory thermoplastic and thermosetting Polyetherimides was given.