Aminosilane grafting of plasticized poly(vinyl chloride) I. Extent and rate of crosslinking

Abstract

The grafting of poly(vinyl chloride) (PVC) by reactive aminosilane com- pounds, which make them moisture-curable, has been investigated. Plasticized poly- (vinyl chloride) has been successfully grafted with aminosilane during extrusion. The grafted polymer was crosslinked in the presence of moisture. Although the hydrolysis and condensation of the crosslinking agent is very rapid, the speed of the reaction is controlled by the rather slow diffusion of water in the plasticized PVC. This water diffusion speed follows Fick's Law and is strongly dependent on temperature. To achieve a high crosslinking speed, the extruded PVC has to be placed in warm water or in a steam heated vessel. The effects of catalyst concentration, moisture concentration, and immersion time and temperature on the rate and degree of crosslinking were investi- gated. Since the formulation used contained a tin stabilizer, the addition of a tin catalyst to the immersion water had little effect. Crosslinking did occur in samples stored at room temperature due to the presence of moisture, but the reaction rate was increased substantially if the sample was immersed in water. Reaction rate was very temperature dependent and followed an Arrhenius relationship. q 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2111-2119, 1997