화학공학소재연구정보센터
Rheologica Acta, Vol.42, No.1-2, 118-122, 2003
Using oscillatory squeezing flow to measure the viscoelastic properties of dental composite resin cements during curing
We have investigated the rheological changes in two particulate-filled dental composite resin cements during the curing process using a Micro-Fourier Rheometer (MFR). In the MFR, the sample was sandwiched between two parallel plates and pseudorandom small amplitude squeezing was applied by oscillating the upper plate over a range of frequencies. Fourier transforms of the displacement signal and the resulting time dependent force signal enabled the rapid determination of the dynamic properties G' and G" over the frequency range 2pi-200pi rad/s. This technique permitted us to follow changes in the rheological properties of the resin cements through the setting period. A typical result was that G' increased from 2 x 10(3) Pa to 2 x 10(5) Pa after about 120 s, and that G" changed from 4 x 10(3) Pa to 4 x 10(4) Pa over the same period at frequency 40pi rad/s. We also found that the dental composite resin cements show linear viscoelastic behaviour over a range of strain amplitudes before curing, but the response becomes distinctly non-linear at the later stages of curing for strain amplitudes, gamma > 0.067 %.