Ping Jiang
Tel: 93512252 (office RM307), pjiang@mech.eng.usyd.edu.au
PhD Research Title: Concentration Dependence of Viscoelastic Material Functions of Non-colloidal Suspensions
Objective:
The aim of this research is to investigate the linear viscoelastic material functions of non-colloidal suspensions, eg. Silicon Oil and Sepran, incorporated with spherical polyethylene beads. It supports the hypothesis based on a simple constitutive model developed by Prof. Phan-Thien. The model suggests that for a certain particulate system, the concentration dependence of the rheological properties should be similar.
Rheological Characterisation of Dental Composite Resin Cements during Curing
Background:
We have investigated the rheological
changes occurring in two particulate filled dental composite resin cements during the
curing process using a Micro-Fourier Rheometer (MFR) (Field, Swain and Phan-Thien, J.
Newtonian Fluid Mech. 65,177-194(1996)). In the MFR, the sample was sandwiched between two
parallel plates, and small amplitude random squeezing was applied by displacing the upper
plate with a sequential range of frequencies. Fourier transformation of the resulting time
dependent force and displacement signals enabled the rapid determination of the dynamic
properties G', G" and Eta' over the frequency range 0-100Hz. This technique permitted
us to follow changes in the rheological properties of the dental composite resin cements
through the setting period. A typical result was that G' increased from
(2 103 )Pa to (2 105) Pa after about 120secs, and that G" changed from (4 103) Pa to
(4 104)Pa over the same period at frequency 20Hz. We also found that the dental composite
resin cement materials shows linear viscoelastic behaviour over a range of strain
amplitudes before curing but shows non-linear behaviour after curing for strain amplitudes
g > 0.67%.
