Experimental Results and Discussion of Piezoelectric Relaxation

In the case of PPO (Fig. 11), CDA, and CTA (Fig. 12), d decreases with increasing temperature in the region of mechanical relaxations and d exhibits peaks in the same region. On the other hand, as illustrated in Fig. 13, d in polypeptides has a maximum and a minimum, and d accordingly changes its sign with temperature. This maximum and minimum of d may, however, be mostly ascribed to the temperature dependence of the elastic modulus, and e shows a similar behavior to that in PPO and other polymers. 

In Table 1 the characteristic values of piezoelectric relaxation are listed. Values of Ad are estimated from the difference between the high- 

Polymer Poly(D- propylene oxide) Cellulose triacetate Cellulose diacetate Polyfy-methyl L-glutamate) (a-helix) 

Note Signs of Ad, Ae, and d mx are defined as in the original papers. Units are in cgsesu. 

According to a dynamic mechanical study by Saba, Sauer, and Woodward (1963) for PPO and a dilatometric study by Daane and Barker (1964) for cellulose acetate, the high-temperature relaxations of PPO, CDA, and CTA are primary relaxations which arise from segmental motion in the amorphous phase and the low-temperature relaxations are presumably ascribed to a more local motion in the amorphous phase. 

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