Birefringence polycarbonate disk

Figure 7.2. Birefringence distribution along the diameter of an injection-molded polycarbonate disk. Reproduced with permission from reference 10. Copyright 1986 John Wiley and Sons.)...

Fig. 24. Birefringence (path difference) of a compact disk, made from CD-modified BPA polycarbonate (191). Q, max value Q, min value (—), mean value.

Fig. 26. Qualitative compatison of substrate materials for optical disks (187) An = birefringence IS = impact strength BM = bending modulus HDT = heat distortion temperature Met = metallizability WA = water absorption Proc = processibility. The materials are bisphenol A—polycarbonate (BPA-PC), copolymer (20 80) of BPA-PC and trimethylcyclohexane—polycarbonate (TMC-PC), poly(methyl methacrylate) (PMMA), uv-curable cross-linked polymer (uv-DM), cycHc polyolefins (CPO), and, for comparison, glass.

Schmidt, L. B., et al., Injection Molding of Polycarbonate Compact Disks Relationship between Process Conditions, Birefringence, Block Error Rate, SPE-ANTEC, 1992. 

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