Coincidence Doppler broadening spectroscopy in polyvinyl chloride after doping with Al 2 O 3

Coincidence Doppler broadening of annihilation radiation (CDBAR) and Vickers hardness techniques were performed to study pure Al 2 O 3 , pure polyvinyl chloride (PVC), and doped PVC with different concentrations of Al 2 O 3 (10–50%). The CDBAR ratio curves with respect to pure PVC were presented and reflect the momentum distribution of all the samples. The peak around 14.5 ×10 −3 m o C in the CDBAR ratio curves suggests a large contribution of positron annihilation with the Al 2 O 3 . There is a linear correlation between the height of this peak and the Al 2 O 3 concentration. The S ‐ and W ‐parameters were extracted from the CDBAR spectra and increase with increasing the Al 2 O 3 concentration showing discontinuity at 30% of Al 2 O 3 concentration on PVC. The present data confirmed that there is no positronium formation in pure Al 2 O 3 as a result of smaller S ‐parameter. The Vickers hardness increases with increasing the Al 2 O 3 concentration in PVC showing a linear dependence with two different slopes depend on the Al 2 O 3 concentration range. A correlation between the Vickers hardness (macroscopic data) and the W ‐parameter (microscopic data) was observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008