Original scientific paper
A Study of Residual Monomer in Poly(methylmethacrylate) Resins by Infrared Spectrophotometry
Đim Pavičić
; D om zdravlja »Trnje«, Zagreb, Hrvatska
Vjekoslav Jerolimov
; School of Dental Medicine, University of Zagreb, Zagreb, Croatia
Radovan Dejanović
; L aboratorij za kem ijsko-fizikalne analize C entra za krim inalistička vještačenja M U P-a R epublike H rvatske, Zagreb, Hrvatska
Abstract
The aim of this study was to determine, by means of infrared spectrophotometry, the amount of residual monomer in two polymer
powder variants (colored and non-colored) of the same industrial PMMA product and in polymerized preparations of the two materials obtained by different short-term procedures of polymerization, in order to study the interrelationship between the finding of residual monomer of polymerized powder and the respective PMMA polymerisate, and to assess the value of infrared spectrophotometry
(spectroscopy) in quantifying residual monomer in poly(methylmethacrylate) resins. Two variants of the same product, i.e. Biocryl B (unstained) and Biocryl R (stained) basic poly acrylate, manufactured by Galenika, were used. PMMA powders of the two materials and their acrylate preparations polymerized by two procedures of polymerization, i.e. heterogeneous heating (fractional, classical) and Presstherm procedure (Bego), were studied. The amount of residual monomer was determined on a FTIR Perkin Elmer 1750 spectrophotometer. Data processing was done on a Perkin Elmer 7700 Professional Computer data unit, using a quantitative CIRCOM program. Poly (methylmethacry late) powders of the materials used in the study were found to contain high amounts of residual monomer. The finding of residual monomer was lower in polymerized prepa-rations than in the original PMMA powder, but was statistically significantly lower in preparations polymerized by the procedure of heterogeneous heating only, revealing the Presstherm procedure to need corrections. Shortterm procedures of polymerization taking 2 hours were shown to be inadequate, leaving a high amount of residual monomer in the polymerisate. Thus, long-term polymerization procedures, such as 7 h at 70°C with at least l h more at 100°C, should be performed whenever possible. There was no statistically significant difference in the findings o f residual monomer between the two variants o f the material used in the study, although stained material had consistently lower values in all comparable groups. Spectrophotometry was found to be a good technique for demonstration o f the amount o f residual monomer, with some limitations requiring further studies in the field.
Keywords
residual monomer; PMMA powder; short-term polymerization; infrared spectrophotometry
Hrčak ID:
100761
URI
Publication date:
15.9.1992.
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