An analysis of the orientational birefringence of poly(methyl methacrylate) in terms of the Mooney-Rivlin equation

✍ Scribed by Yue Zhao

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 303 KB
• Volume: 28
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(92)90067-c

✦ Synopsis

A~traet--The orientational birefringence of poly(methyl methacrylate) (PMMA) was analysed using the Mooney-Rivlin equation. It is shown that its dependence on strain can be well described by this equation over more than three decades of time (in seconds). More interestingly, the B~ term (usually found and ascribed to some temporary affine deformation upon stretching in uncrosslinked polymers) is absent for PMMA within the error of experimental measurements. The B 2 term is shown to be governed by the chain relaxation that takes place during stretching, emphasizing its molecular origin associated with the entanglement network. Also, a comparison of B t and B 2 for PMMA and polystyrene (PS) indicates clearly a significant difference between the deformation behaviour of the entanglement network for the two polymers. The B~ term of PS gives an important contribution to the orientational birefringence, and relaxes with time in a similar way to B 2.