CRYSTAL-GROWTH OF INTERMEDIATE-MOLECULAR-MASS POLY(ETHYLENE OXIDE) FRACTIONS FROM THE MELT

Linear crystal growth rates of poly(ethylene oxide) (PEO) fractions crystallized from the melt have been measured in an intermediate-molecular-mass range (MW = 23 000-105 000). Regime phenomena have been observed during crystallization. Regime II/III transitions occur at ΔT = 17.5±0.5 K and regime I/II transitions appear at ΔT = 10±0.5 K for those fractions for which the equilibrium melting temperature of 342.2 K for PEO crystals is used. Interestingly, we have found that in these PEO fractions reversion from regime I back to regime II exists even at a lower supercooling of 8.5±0.5 K. Detailed kinetic analyses of the data demonstrate the suitability of the present nucleation theory. The molecular-mass dependence of the PEO fraction has also been discussed. Morphological changes can be observed along with regime transitions of PEO crystal growth. © 1990.