PP熔体分子量、零切粘度与纺丝机管路中停留时间的关系

RELATIONS BETWEEN THE MOLECULAR WEIGHT,THE ZERO SHEAR VISCOSITY AND THE RESIDENCE TIME IN THE DELIVERY PIPE OF THE SPINNING MACHINE OF PP MELT

将PP树脂通过螺杆挤压机加热熔融,在272℃时将熔体在输送管路中分别停留一定时间,然后测定特性粘度,从而研究PP的热降解特性。求出272℃时3702和5028BL两种PP的分子量表观下降速率常数分别为1.293×10-7和3.334×10-7min-1,导出了粘均分子量、零切粘度与停留时间的关系式,指出272℃时合适的纺丝熔体粘度为90—161Pa·s。当进入管路的熔体粘度为212Pa·s时,熔体在管路中的停留时间为3—13min（3702）和1.5—5min（5028BL）。

At the temperature of 272℃, making the PP resin melted in the screw extruder have a certain residence time in the delivery pipe, then determining the inherent viscosity, the thermodegradation characteristics of PP resin were studied. It is found that the apparent rate constants of the molecular weight's decrease are 1.293×10^(-7) and 3.334×10^(-7)min^(-1) respectively. The relations between viscosity average molecular weight, zero shear viscosity and residence time have been deduced. It has been proved that the proper viscosity of spinning melt at 270℃ is 90—161 Pa.s. If the melt viscosity is 212 Pa.s at the entrance of the conduit, the residence time is 3—13 min for type 3702 and 1.5—5 min for type 5028 BL.