ASSESSMENT OF DEGREE OF FUSION OF RIGID PVC FROM INVERSE GAS-CHROMATOGRAPHIC MEASUREMENTS

Inverse gas chromatography of alkanes has been used to assess the degr ee of fusion of rigid polyvinyl chloride (PVC) extrudates. The relativ e degree of fusion is provided by ratios of the retention volumes of t he alkane probe molecules in the bulk of the PVC. This method is nonin trusive and can be used to measure degree of fusion quantitatively if a completely fused reference material can be provided. The present ana lysis involves evaluations of the contributions to the overall retenti on volume of the alkane probes, resulting from adsorption and from bul k diffusion. The diffusivity of the alkanes was clearly dependent on t he processing history of the PVC extrudate. A direct variation was obs erved between the size of the diffusing molecules and their residence time as adsorbates on the polymer surface. (C) 1995 John Wiley and Son s, Inc.