KINETICS OF POLY(ETHYLENE OXIDE) CRYSTALLIZATION FROM SOLUTION - TEMPERATURE AND MOLECULAR-WEIGHT DEPENDENCE

The rate of crystal growth from dilute solutions of poly(ethylene oxide) (PEO) of high and intermediate molecular weight has been investigated by utilizing a new seeding technique in conjunction with dynamic light scattering. Crystallization of polymers in a dilute solution is initiated by the addition of seed crystals and the growth kinetics are monitored by repetitive measurements of diffusion coefficients of crystal particles. The crystal growth rate can be extracted from the linear plot of inverse decay constant of scattering particles vs time. It has been found that the temperature influence on crystal growth kinetics in terms of log G vs 1/T-DELTA-T depends on the choice of T(d)-degrees. Regardless of the exact values of T(d)-degrees used for the range of molecular weight samples, it is found that for high PEO molecular weights (> 3 x 10(5)) a transition could be recognized in the dependence of the growth rate on the extent of supercooling. No such transition is found for intermediate (< 3 x 10(5)) molecular weight PEO. At constant supercooling, the growth rate generally increases with polymer molecular weight over the range from 5.63 x 10(4) to 7.7 x 10(5).