The die swelling of polycarbosilane and the profile degree of Y-shaped SiC fibers
聚碳硅烷的挤出胀大与Y型SiC纤维的异形度

The die-swell mechanism of polycarbosilane(PCS) melt for a spinneret with Y-shaped orifice and the effect of die swelling of PCS on the profile degree (PD) of Y-shaped SiC were investigated. For a spinneret with circular holes, the die-swell ratio was in the range of 1.02-1.15, while for a spinneret with Y-shaped orifices, the ratio is 1.02-1.43. The die-swell ratio for a spinneret with Y-shaped orifices was about 15% higher than that with circular holes in the same forming condition. The asymmetric distribution of shear stress in the circumference of the Y-shaped orifice and the different shear stress in the orifice profiles were the fundamental reasons for the increase of the die-swell ratiofor the Y-shaped orifice. In comparison with the PD of the orifice, there was a reduction of 10%-20% in the PD of the fibers.