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 beha vior of thick parts. Conditions under which different crystalline forms of polypropylene are obtained as a function of cooling rate and spinline stres s were investigated. Continuous cooling transformation (CCT) curves are dev eloped. This also allows us to develop a map of crystalline form as a funct ion of these variables. We have applied the CCT curves and this map to pred ict the development of cross-sectional variation structure in thick filamen ts and rods. This is applied in particular to the quenching of a cylindrica l rod and the structural characterizations observed through the cross secti on are compared with predictions from the CCT curves and solutions of Fouri er's transient heat conduction equation.