AbstractThe molecular orientation distribution of injection‐molded polycarbonate discs is studied using birefringence and heat‐shrinkage measurements and laser‐Raman spectroscopy. Birefringence and heat shrinkage, which result from the molecular orientation, increase as the distance from the inflow gate decreases and as cylinder temperature decreases. Molecular orientation is reduced following annealing. Laser‐Raman spectroscopy is used to measure the molecular orientation distribution along the disc cross‐section perpendicular to the radial direction of disc. The relative intensity ratio for the 635 cm−1and 703 cm−1peaks in the Raman spectra correlate well with the degree of molecular orientation. The disk cross‐section is found to consist of three different molecular orientation zones; a skin zone which is in contact with the mold, a core zone located at the center, and a shear zone between the skin and the core zones. Molecules in the skin zone are nonoriented while the orientation of molecules in the core zone is considerably relaxed. The shear zone consists of highly oriented molecules. The formation process of the molecular orientation distribution is discussed in relation to birefringence and
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