Correlation and modeling of the occurrence of different crystalline forms of isotactic polypropylene as a function of cooling rate and uniaxial stress in thin and thick parts

A study of structure development in thin melt spun isotactic polypropylene filaments is described, which is then applied to the prediction of the behavior of thick parts. Conditions under which different crystalline forms of polypropylene are obtained as a function of cooling rate and spinline stress were investigated. Continuous cooling transformation (CCT) curves are developed. This also allows us to develop a map of crystalline form as a function of these variables. We have applied the CCT curves and this map to predict the development of cross-sectional variation structure in thick filaments and rods. This is applied in particular to the quenching of a cylindrical rod and the structural characterizations observed through the cross section are compared with predictions from the CCT curves and solutions of Fourier's transient heat conduction equation.