Thermal expansion behaviour of high performance PEEK matrix composites

Abstract

The thermal expansion behaviour of high performance poly(ether-ether-ketone) (PEEK) composites reinforced with micro- (8 µm) and nano- (39 nm) sized Al2O3 particles was studied. The distribution of Al2O3 in the PEEK matrix was studied by scanning electron microscopy and transmission electron microscopy. The coefficient of thermal expansion (CTE) was reduced from 58 × 10−6 °C−1 for pure PEEK to 22 × 10−6 °C−1 at 43 vol% micro-Al2O3 and to 23 × 10−6 °C−1 at 12 vol% nano-Al2O3 composites. For a given volume fraction, nano-Al2O3 particles are more effective in reducing the CTE of composites than that of micro-Al2O3 particles. This may be attributed to the much higher interfacial area or volume of nanocomposites than that of microcomposites. The upper limit and lower limit of the Schapery model separately fit closely the CTE of the micro- and nano-composites, respectively. Other models such as the rule of mixture and Kerner and Turner models were also correlated with the data.