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Melt viscosity characteristics of methacrylate–styrene copolymers
Author(s) -
Terrell D. R.,
Katiofsky H.
Publication year - 1977
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1977.070210514
Subject(s) - methacrylate , copolymer , polymer chemistry , styrene , materials science , monomer , acrylonitrile , methyl methacrylate , molar mass , polymer , composite material
The activation energies of flow E A of methacrylate–styrene copolymers containing n ‐butyl, n ‐hexyl, n ‐heptyl, n ‐octyl, n ‐decyl, n ‐dodecyl, n ‐tridecyl, n ‐octadecyl, and cyclohexyl methacrylate have been investigated as a function of molecular weight, composition, and methacrylate monomer. Below a critical pendent group molar volume per chain unit (120 ± 10 ml Le Bas units), E A was found to increase with molar volume; and above this value, a decrease in E A was observed, reflecting a decrease in copolymer density. Copolymers with pendent group molar volumes per average chain unit of between 96 and 140 ml (Le Bas units) were found to exhibit sufficiently high E A values to render them suitable for use in thermoplastic and photothermoplastic devices with superior development and erasure rates, at temperatures which enabled the attainment of the development and erasure viscosities with a low expenditure of heat energy. Methacrylate–styrene copolymers with long‐chain ester methacrylates (viz., n ‐decyl and n ‐dodecyl methacrylate) were found to exhibit critical molecular weights M c below 3000; and M c was found to decrease with increasing methacrylate tail length and methacrylate concentration. These M c values correspond to critical chain lengths Z c below 45. Similar Z c values have been previously reported for acrylonitrile–methyl methacrylate copolymers 30 and ethylene–propylene copolymers. 28