X-ray diffraction and differential scanning calorimetry (DSC) studies of isotactic polypropylene fibres, produced by melt spinning with take-up speeds of 2500-4250 m/min, showed the presence of polymorphism where the a-monoclinic and the smectic phases coexist together with an amorphous phase. X-ray diffraction was used for the determination of the unit cell dimensions, crystalline density, crystallinity and the crystallite size using an analysis of the equatorial traces whereas DSC was used for the evaluation of the melting enthalpies, melting temperatures and the crystallinity as a function of take-up speed. Crystallinity evaluated with the X-ray diffraction and the DSC techniques are compared and found that the X-ray crystallinity values are on average 8-14% higher than the DSC crystallinity values. Crystallite sizes are evaluated after curve fitting of X-ray diffraction traces for the (110), (040) and (130) reflections due to the a-monoclinic phase. The results show the crystallite size distribution of 116-136 angstrom, 108-118 angstrom and 89-97 angstrom for the alpha-monoclinic phase reflections, whereas smectic phase reflection showed smaller crystallite size of 11-13 angstrom due to large intensity distribution of this peak.
X-ray diffraction and differential scanning calorimetry (DSC) studies of isotactic polypropylene fibres, produced by melt spinning with take-up speeds of 2500-4250 m/min, showed the presence of polymorphism where the ?-monoclinic and the smectic phases coexist together with an amorphous phase. X-ray diffraction was used for the determination of the unit cell dimensions, crystalline density, crystallinity and the crystallite size using an analysis of the equatorial traces whereas DSC was used for the evaluation of the melting enthalpies, melting temperatures and the crystallinity as a function of take-up speed. Crystallinity evaluated with the X-ray diffraction and the DSC techniques are compared and found that the X-ray crystallinity values are on average 8-14% higher than the DSC crystallinity values. Crystallite sizes are evaluated after curve fitting of X-ray diffraction traces for the (110), (040) and (130) reflections
due to the ?-monoclinic phase. The results show the crystallite size distribution of 116-136 Å, 108-118 Å and 89-97Å for the ?-monoclinic phase reflections, whereas smectic phase reflection showed smaller crystallite size of 11-13 Å due to large intensity distribution of this peak.
