The intrinsic viscosity-molecular weight relationship for polypropylene

Measurements of intrinsic viscosity in decalin at 135°C and light scattering in α-chloronaphthalene at 145°C were performed for several polypropylene fractions of molecular weight ranging up to 2.106. The specific refractive index increment at 436 mμ for the α-chloronaphthalene solution was found to be −0.231 ml/g, which is considerably higher than those reported by CHIANG and others authors. However, no significant disparity is observed between the results of light scattering measurements by CHIANG and the present author. The intrinsic viscosity-molecular weight relationship obtained is: [η] = 1.15·10−4 M, which is in good agreement with that reported by KINSINGER and HUGHES. This relationship is also compared with those of other authors observed at different conditions of viscosity measurements.