Abstract
Zirconium tungstate powder was added to three bisphenol-A-based epoxy resins in different loadings up to 1 wt%. Zirconium tungstate (ZrW2O8) is known to have a negative coefficient of thermal expansion (CTE), and the effect of the added powder on the composite material's CTE and glass transition temperature (Tg) was assessed using dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA). The Tg of all three resins was observed to decrease with increasing ZrW2O8 loading. However, while the CTE in the sub-Tg temperature range was observed to decrease in all three resins with increasing ZrW2O8 loading, the CTE at temperatures above Tg was found to increase with increasing ZrW2O8 loading. It is thought that this behaviour is caused by an increase in free volume within the polymer since the zirconium tungstate is contracting in size with increasing temperature.