Kinetics of sono-photooxidative degradation of poly(alkyl methacrylate)s

Vinu, R and Madras, Giridhar (2011) Kinetics of sono-photooxidative degradation of poly(alkyl methacrylate)s. In: Ultrasonics Sonochemistry, 18 (2). pp. 608-616.

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Abstract

The mechano-chemical degradation of poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA) and poly(n-butyl methacrylate) (PBMA) using ultrasound (US), ultraviolet (UV) radiation and a photoinitiator (benzoin) has been investigated. The degradation of the polymers was monitored using the reduction in number average molecular weight (M-n) and polydispersity (PDI). A degradation mechanism that included the decomposition of the initiator, generation of polymer radicals by the hydrogen abstraction of initiator radicals, reversible chain transfer between stable polymer and polymer radicals was proposed. The mechanism assumed mid-point chain scission due to US and random scission due to UV radiation. A series of experiments with different initial M-n of the polymers were performed and the results indicated that, irrespective of the initial PDI, the PDI during the sono-photooxidative degradation evolved to a steady state value of 1.6 +/- 0.05 for all the polymers. This steady state evolution of PDI was successfully predicted by the continuous distribution kinetics model. The rate coefficients of polymer scission due to US and UV exhibited a linear increase and decrease with the size of the alkyl group of the poly(alkyl methacrylate)s, respectively. (C) 2010 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	Ultrasonics Sonochemistry
Publisher:	Elsevier Science
Additional Information:	Copy right of this article belongs to Elsevier Science.
Keywords:	Ultrasound; Ultraviolet; Sonochemical; Photochemical; Sonophotochemical; Poly(alkyl methacrylate)
Department/Centre:	Division of Mechanical Sciences > Chemical Engineering
Date Deposited:	12 Jan 2011 10:35
Last Modified:	12 Jan 2011 10:35
URI:	http://eprints.iisc.ac.in/id/eprint/34902

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