On the PEEK composites reinforced by surface-modified nano-silica

The nano-sized silica fillers reinforced poly(ether ether ketone) (PEEK) composites were fabricated by means of compression molding technique. he nano-sized silica, measuring 30 nm in size, was firstly modified by surface pretreatment with stearic acid. The performances and properties f the resulting PEEK/SiO2 nanocomposites were examined in terms of tensile loading, hardness, dynamic mechanical analysis (DMA), theromechanical analysis (TMA), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning lectron microscopy (SEM) and transmission electron microscopy (TEM). The modified nano-silica was seen to disperse more uniformly than he unmodified counterpart. The XRD patterns of the modified silica reinforced PEEK composites reveal a systematic shift toward higher angles, uggesting the smaller d-spacing of the PEEK crystallites. The coefficient of thermal expansion (CTE) becomes lowered when the content of he nano-silica increases. Furthermore, the CTE of the modified silica filled PEEK nanocomposites shows the higher CTE values. A logic model s proposed. The increment of the dynamic modulus for the PEEK nanocomposites is up to 40% at elevated temperatures from 100 to 250 ◦C, ndicating the apparent improvement of elevated temperature mechanical properties. 2007 Elsevier B.V. All rights reserved.