Thermomechanical investigation of poly(methylmethacrylate) containing an organobismuth radiopacifying additive

Henry R Rawls, Randall J. Granier, Johannes Smid, Israel Cabasso

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Previously we demonstrated the feasibility of using up to 24% triphenylbismuth (TPB) as a radiopaque, monomer-miscible additive for dental acrylic resins. In this study we examined the influence of TPB on thermomechanical properties of a representative polymethylmethacrylate (PMMA) ambient-cured resin used for temporary dental crowns and bridges. TPB (0%, 5%, 15% or 30% w/w) was dissolved in the monomer component, added to the powder component, and allowed to cure in rectangular molds. After 1 h they were either stored at 23°C for 23 h, or heated for 5 min at either 40°C or 50°C, and then stored for 23 h. They were then scanned from 10° to 125°C in a dynamic mechanical thermal analyzer using the three-point bending mode of deformation at 1-Hz frequency. The onset to the glass-transition temperature (T(g)) is decreased by 13° to 32°C by addition of TPB, while the storage modulus (E') at 25°C is either unchanged or is slightly increased. TPB did not interfere with the curing reaction, and postcure heating at 40°C had no effect on either E' or T(g). However, heating at 50°C generally increased T(g) but had very little effect on E' throughout the 0-50°C operating temperature range. TPB crystals were observed to have precipitated at TPB levels above 8%. These crystals, dispersed throughout the PMMA, act as reinforcing fillers. This reinforcement can account for the lack of a decrease in E', as would be expected if TPB had a plasticizing effect below T(g). However, even at 5%, a concentration at which all the TPB remains dissolved in the solid polymer, no decrease in E' was observed. This implies that TPB exerts an antiplasticizing effect at temperatures below 50°C, possibly by occupying free volume among the polymer chains. It is concluded that TPB, in amounts adequate to impart diagnostic levels of radiopacity, is unlikely to adversely affect the clinical utility of PMMA-based dental acrylic resins.

Original languageEnglish (US)
Pages (from-to)339-343
Number of pages5
JournalJournal of Biomedical Materials Research
Volume31
Issue number3
DOIs
StatePublished - Jul 1996

Fingerprint

Methylmethacrylate
Resins
Acrylics
Monomers
Heating
Crystals
Free volume
Molds
Polymers
Curing
Polymethyl Methacrylate
Fillers
Reinforcement
Synthetic Resins
Elastic moduli
Acrylic Resins
Powders
Temperature
triphenyl bismuth
Tooth Crown

ASJC Scopus subject areas

  • Biomedical Engineering
  • Biomaterials

Cite this

Thermomechanical investigation of poly(methylmethacrylate) containing an organobismuth radiopacifying additive. / Rawls, Henry R; Granier, Randall J.; Smid, Johannes; Cabasso, Israel.

In: Journal of Biomedical Materials Research, Vol. 31, No. 3, 07.1996, p. 339-343.

Research output: Contribution to journalArticle

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