EFFECT OF THE MELT STRUCTURE ON THE THERM ODYNAMICS AND KINETICS OF ORIENTATIONAL CRYSTALLIZATION OF A FLEXIBLE-CHAIN POLYMER

The crystallization of a uniaxially oriented melt of a flexible-chain polymer was studied. At a deformation exceeding the critical level, th e oriented melt forms an equilibrium microfibrillar crystal structure upon solidification . The critical deformation value depends on the po lymer MM and the average number of units between the neighboring chain entanglements in the melt. Analytical expressions are obtained for th e degree of crystallinity as a function of geometric parameters that d escribe the final microfibrillar crystalline state and for the kinetic s of isothermal crystallization of the oriented melt of the flexible-c hain polymer. The obtained expression for the kinetics of orientationa l crystallization can be replaced, in principle, by a simplified Avraa mi equation. To this end, the exponent n in this equation must be assu med to decrease as the phase transformation comes to completion.