CRYSTALLIZATION OF SYNDIOTACTIC POLYSTYRENE IN BETA-FORM .3. ENERGETIC ANALYSIS OF THE INCORPORATION MECHANISM OF STACKING-FAULTS INTO THE CRYSTAL

Crystallization-temperature (T-c) dependence of the probability of the presence of stacking faults, p, in the solution-grown beta-form singl e crystal of syndiotactic polystyrene (s-PS) was analyzed on the basis of the growth theory of the polymer crystal. By comparing the experim entally obtained T-c dependence of p with the theoretical one, it is d educed that the relative energy difference, Delta E/Delta h(f), betwee n the regular and the faulted structures of s-PS decreases linearly wi th increasing T-c: Here, (Delta h(f)-Delta E) and Delta h(f) mean the heat of fusion for the faulted structures and that for the regular one , respectively. This result leads to an expectation that the faulted s tructure will be dominant when T-c is above a certain critical tempera ture. Such a fault-rich crystal is to give the hk0-diffraction pattern , in which the reflections with h + k = odd are absent. This feature h as been really found in the X-ray diffraction pattern from the beta'-f orm crystal by De Rosa et al.