The behaviour of a quenched ethylene-propylene block copolymer cast film has been investigated during melting and recrystallization experiments carried out at heating and cooling rates of 10°C min-1. The experimental techniques used to follow the melting and recrystallization processes were differential scanning calorimetry (d.s.c.) and simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). In particular, the WAXS results show that the melting of the material is preceded by a solid-state transition involving transformation of the quenched structure into the monoclinic ~ modification. This transition appears as an exotherm in the range 65-120°C on the d.s.c, melting trace. SAXS results show that an increase in the amount of long-range order occurs during this transition. The sample was then found to melt at 162°C. Upon cooling from the melt, recrystallization of the monoclinic ct modification was found to occur in the range 123-105°C without any apparent prior formation of the quenched structure.
Посилання на статтю:
Simultaneous SAXS/WAXS and d.s.c. analysis of the melting and recrystallization behaviour of quenched polypropylene / W. J. O'Kane, R. J. Young* and A. J. Ryan // Polymer. – 1994. – Vol 35. – P. 1352-1358.