On-line estimation of molecular orientation in polypropylene fibers using polarized Raman spectroscopy

Polarized Raman spectra obtained at different points along the spin line du ring pilot-scale melt spinning of polypropylene fibers are presented for th e first time. Measurements of the 841/809 cm(-1) band intensity ratio for t hese fibers with varying draw are made and shown to correlate with birefrin gence. The effect of sample throughput and take-up velocity on real-time po larized Raman spectra of these fibers is also discussed. On the basis of th e results obtained it is confirmed that the ratio of the 841/809 cm(-1) ban d intensities can be used to estimate the molecular orientation in polyprop ylene fibers.