CORRELATIONS BETWEEN RELAXATION-TIME SPECTRUM AND MELT-SPINNING BEHAVIOR OF POLYPROPYLENE .1. CALCULATION OF THE RELAXATION SPECTRUM AS A LOG-NORMAL DISTRIBUTION AND INFLUENCE OF THE MOLECULAR-PARAMETERS
R. Fulchiron et al., CORRELATIONS BETWEEN RELAXATION-TIME SPECTRUM AND MELT-SPINNING BEHAVIOR OF POLYPROPYLENE .1. CALCULATION OF THE RELAXATION SPECTRUM AS A LOG-NORMAL DISTRIBUTION AND INFLUENCE OF THE MOLECULAR-PARAMETERS, Polymer engineering and science, 35(6), 1995, pp. 513-517
The linear viscoelastic behavior of commercial broad-distribution poly
propylenes is studied. The samples underwent different controlled pero
xide degradation rates, so they exhibit different molecular distributi
ons. The relaxation spectrum is obtained by assuming that it takes the
shape of a Log-Normal distribution. It is in agreement with the linea
r viscoelasticity theory by providing limiting values, contrary to oth
er models. Moreover, the ratio tau omega/tau n which takes place in th
is law is very useful to distinguish the synthesis differences of the
samples when the Melt Flow Index alone cannot.