Original scientific paper
Effect of Cross-linking Chain Length on Glass Transition of a Dough-moulded Poly (methylmethacrylate) Resins
Vjekoslav Jerolimov
; Department of Removable Prosthodontics, University of Zagreb, Croatia
Robert G. Jagger
; Department of Prosthetic Dentistry, University of Walles College of Medicine, Dental School, Cardiff, UK
Paul J. Millward
; Department of Prosthetic Dentistry, University of Walles College of Medicine, Dental School, Cardiff, UK
Abstract
The purpose o f the study was to investigate the effect o f the addition o f various divinyl cross-linking agents on the glass transition temperature o f a dough-moulded poly (methylmethacrylate) (PMMA) resin. Three different cross-linking agents, ethylene glycol dimethacrylate (EGDM A), tetra (ethylene glycol dimethacrylate) (TEGDM A) and poly (ethylene glycol dimethacrylate) (PEG 600 D M A), which form an homologous series o f ethylene oxide adducts in which the cross-linking contains one, four and an average o f 13 (C-C-O) units respectively, were added to the M M A monomer component in concentrations o f 0-40% by volume o f monomer liquid concentration. The polymer component was an unpigmented PMMA homopolymer. Specimens were produced in moulds according to conventional dental flasking and curing procedures and measurements o f Tg were determined by thermomechanical analysis. The addition o f EGDM A produced a highly significant increase in Tg at all concentrations. The addition o f TEGDM A produced no significant change at 10% and 20% concentrations but significantly lowered Tg at 30% and 40%. PEG 600 DMA produced significant lowering at all concentrations. It was concluded that cross-linking o f a dough-moulded PMMA resin by divinyl cross-linking agents can significantly affect Tg but that the relationship between Tg, cross-linking chain length and cross-linking agent concentration is complex.
Keywords
denture base acrylic resins; cross-linking; glass transition temperature
Hrčak ID:
99263
URI
Publication date:
15.3.1994.
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