The primary shape (stress-free)of the sample was set to be a linear rectangular bar. The originalshape was easily deformed into spiral shape (a temporary shape) at70 C, which was prepared using a Teflon rod. By subsequentcooling at room temperature, the temporary shape was fixed. Uponreheating above Tm, the deformed shapewas restored to its originalshape. These deformation and recovery processes were repeatedlypracticable.The programming shape memory-recovery cycles of MTPI withdifferent maleic content are depicted in Fig. 6. The sample waselongated at a rate of 1mmmin1 at 60 C. With the maleic contentincreased, the tensile stress of MTPI increased. The temporaryshape was fixed by cooling at a rate of 2 C min1 to 5 C at aconstant stress. DSC results indicate that the melt crystallizationproceeded during the cooling step. MTPI with 1% maleic contentwas slightly deformed because of the loading and the low crosslinkingdensity (low maleic content) during the cooling process.The sample was then unloaded to 0 N. From the observation of thethird step, it can be found that MTPI with 1% maleic content exhibitsbetter shape fixity than MTPI with higher maleic content.This result is attributed to higher crystallinity of MTPI with 1%maleic content. MTPI with higher maleic content could not maintainthe temporary shape. In final step, the sample was reheated ata rate of 2 C min1, and the original shapewas recovered above Tm.MTPI with lower maleic content showed excellent shape memoryrecoverybehavior. On the other hand, MTPI with higher maleiccontent behaved as an elastic material like a crosslinked rubber. Theplausible shape memory-recovery mechanism is as follows. Thedriving force of shape recovery is the elastic force of physicalnetwork. Above Tm, MTPI behaves as an elastic soft material and iseasily deformed. After the subsequent cooling, the melt crystallizationproceeds, and the temporary shape is fixed with the internalstress generated by the deformation. Upon reheating above Tm, themobility of polymer chains increases, and the shape of the samplereturns to the original shape by the rubbery elasticity.