I was wondering which one between films and fibers would be more crystalline if I heat both at same temperature and both are from same precursor material.
Crystallinity depends on the molecular structure, on the thermal prehistory (cooling rate, recrystallization) and on the defromation (elongation) of the sample. Usually extension causes induced crystallization (and orientation). As fibers can be usually deformed beter than films before breakage, I would assume it is easier to make high crsytallnity samples by fiber spinning or drawing. It ican be relatively easily checked by DSC, X-ray. X ray photographs (not powder diffcation) may even help to decide the orientation effects.