Methyl methacrylate monomer-polymer equilibrium in solid polymer.

C Y K Lung; B W Darvell

doi:10.1016/j.dental.2005.12.004

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PubMed · 16430955

Methyl methacrylate monomer-polymer equilibrium in solid polymer.

C Y K Lung·B W Darvell

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Abstract

OBJECTIVE: Poly(methyl methacrylate) (PMMA) is commonly processed in dentistry by thermally initiating the free-radical polymerization of methyl methacrylate (MMA). Residual MMA, a tissue irritant, is a concern. The concentration of MMA ([MMA]) versus time and temperature was studied to identify optimum processing conditions. MATERIALS AND METHODS: One hundred milligram portions of plain and dental PMMA powders were incubated (10-170 degrees C, 1-384 h), with and without 6.0 microL MMA added. After incubation, [MMA] was determined by GC. RESULTS: For plain PMMA alone, equilibrium was attained in about 100 h. The equilibrium data for log[MMA] versus 1/T was better fitted by a quadratic than a straight line, and formed an upper bound to the values of [MMA] when PMMA was incubated with MMA at temperatures > approximately 120 degrees C. The response surface for [MMA] versus log(time) and reciprocal temperature was fitted. An 'overshoot' in the equilibration process was identified, and postulated to be due to a rapidly formed intermediate of unknown chemistry. SIGNIFICANCE: Minimization of the residual MMA in acrylic denture bases prepared by processing a mixture of PMMA and MMA is important for reasons of mechanical properties and irritancy. The response surface mapped here allows direct identification of the optimum processing conditions.

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Chemical Phenomena Chemistry, Physical Chromatography, Gas Dental Materials Humans Materials Testing Methylmethacrylates Models, Chemical Polymers Polymethyl Methacrylate Powders Temperature Time Factors Journal Article

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C Y K Lung, B W Darvell. 2006-01-23. Methyl methacrylate monomer-polymer equilibrium in solid polymer.. https://doi.org/10.1016/j.dental.2005.12.004

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