Abstract
In melt spinning of polypropylenes having various molecular weight, diameters of stream were measured along the spinning way by microscopic photograph. The distribution of extensional strain rate for distance from nozzle (dV/dX-X) was estimated from stream diameters. Its distribution curve has a maximum value which is increasing linearly with take-up velocity. The maximum extensional strain rate ((dV/dX)max) in breaking was obtained by extrapolation to breaking take up velocity for each sample.
In the same manner with the exception of take-up, gravitational stressing spinning has been carried out. Relationship between load and fall velocity in gravitational stressing spinning was obtained for various samples. On the other hand, its relationship was theoretically estimated from equilibrium of forces using as a parameter
η* (extensional viscosity). From comparison of both relationship, extensional viscosities of melt spinning were determined.
Tensile stresses in breaking_??_max were calculated by following equation;
Calculated values of tensile stress in this breaking remained over various molecular weight samples.
