Abstract
This study investigates the effect of two different types of organic coating applied to titanium dioxide pigment on the processing and properties of rigid PVC. The first pigment was coated with polyol and siloxane, whereas the second pigment was coated just with polyol. The surface energies of the two coated pigments were determined by contact angle measurements. It was found that the pigment coated with both polyol and siloxane was more hydrophobic and gave better dispersion behaviour than the other pigment. The coated TiO2 pigments were dry blended in a calcium-zinc stabilised PVC window profile formulation and extruded on a laboratory-scale extruder. Fusion properties and impact strength were measured and there was found to be a small but significant improvement in these properties for the formulation containing the first pigment compared with that containing the second. Hence the improvements in processing and properties correlated with the hydrophobicity and dispersability of the two different pigments.
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