Crystallization phenomena in fibre‐forming polymers

Abstract

Abstract The present position reached in a general study of how fabrication conditions affect the crystalline texture and therefore the properties of crystalline polymers is reviewed. The mechanism by which long‐chain molecules order themselves into some form of crystalline array is postulated to be one involving normal nucleation processes, but modified to take account of the fact that polymers melt over a range of temperatures, and the nucleation act is followed by preferential crystal growth in the direction of the polymer chains. This mechanism, with the additional concept of coiling growth, is not inconsistent with kinetics that fit the crystallization‐rate processes on the one hand and observable structure in crystalline polymers on the other. It is considered that lateral accretion of the polymer molecules to the already formed long helical polymer‐crystal results in haphazard branching growth with the new fibril developing along a path parallel to the parent crystal. This leads to the formation of coiled families of fibrillar crystals and this structure appears to be a suitable model on which to explain the many wide‐angle and low‐angle X ‐ray observations that have been made at various stages of the drawing and relaxing of filaments of crystalline polymers.