Investigation of orientation and relaxation in a segmented zwitterionomer by fourier transform infrared spectroscopy

The orientation behavior of a segmented poly(tetramethylene oxide) (PTMO) z witterionomer, with a narrow polydispersity PTMO segmental molecular weight of 5.2 x 10(3), a melting point of 17 degreesC, and elastomeric characteri stics, was studied using infrared linear dichroism. The results obtained sh ow that when the amorphous zwitterionomer is stretched at ambient temperatu re, the PTMO chains orient in the stretch direction. At a draw ratio of app roximately 3, strain-induced crystallization occurs and increases with stra in amplitude. The chain axis of the crystallized PTMO segments are almost p erfectly oriented in the stretch direction, whereas the orientation of the amorphous segments is low and undergoes no further changes during crystalli zation. The degree of crystallization was also determined from the spectra (22% for a draw ratio of 5.6). The crystallization kinetics were shown to f ollow the Avrami equation, indicating one-dimensional growth (n = 0.8). Ori entation relaxation following deformation was also studied as a function of temperature at draw ratios and temperatures where strain-induced crystalli zation is avoided. Little orientation was detected in the ionic regions of the polymer during stretching. The orientation function for the PTMO soft b locks decreases, and the relaxation rate increases with increasing temperat ure. Time-temperature superposition of the relaxation curves is discussed i n relation to the hard (or cluster) phase transition.