Origin of Excess Light Scattering in Poly(methyl methacrylate) Glasses

Yasuhiro Koike, Shiro Matsuoka, Harvey E. Bair

Research output: Contribution to journalArticlepeer-review

68 Citations (Scopus)

Abstract

The origin of the excess light scattering invariably observed in purified poly(methyl methacrylate) (PMMA) glasses was investigated. The isotropic heterogeneous structure with a dimension of about 1000 Å, which increases the scattering loss by at least 1 order of magnitude (to several hundred dB/km), is generated during polymerization below Tg at high conversion and is not due to high molecular weight, specific tacticities, formation of cross-links, or aging. It is clearly shown that the remaining monomer in concentrations of several weight percent does not aggregate spontaneously at high conversion to cause excess scattering unless polymerization takes place. The excess scattering is, we believe, mainly due to voids caused by the volume shrinkage accompanying polymerization of the remaining monomer trapped inside the polymer glass. The excess scattering model proposed in this paper shows that if a slight amount of monomer in the PMMA glass is polymerized in situ at high conversion, generating slightly localized voids due to the aggregation of the unreacted initiator, a rise of only 1 wt % in the conversion increases the scattering loss by several hundred dB/km, which can reasonably explain the experimental results obtained in this paper.

Original languageEnglish
Pages (from-to)4807-4815
Number of pages9
JournalMacromolecules
Volume25
Issue number18
DOIs
Publication statusPublished - 1992 Aug 1

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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