INFRARED SPECTROSCOPIC INVESTIGATION OF BULK-CRYSTALLIZED TRANS-1,4-POLYISOPRENE

Crystallization from the melt of trans-1,4-polyisoprene was followed u sing Fourier-transform infra-red spectroscopy. The spectral subtractio n factor versus time was obtained at the crystallization temperature a nd after cooling to 25-degrees-C for fractions and for the parent mate rial. Crystallization of the beta crystal form was followed at 36 and 43-degrees-C and of the alpha form at 43 and 51-degrees-C. Samples cry stallized at 25-degrees-C and subsequently annealed at 43-degrees-C we re also monitored. The amorphous fraction for prenucleated melt-crysta llized alpha-form-containing samples increased with molecular weight a t the crystallization temperature and after cooling to 25-degrees-C. S amples containing the beta crystal form showed a molecular-weight depe ndence at a crystallization/annealing temperature of 43-degrees-C that disappears upon cooling the sample to 25-degrees-C. The results are d iscussed in terms of lamellar surface disorder and lamellar thickness distribution.