Properties enhancement of fluorosilicone elastomers with compatibilised crystalline vinylidene fluoride polymers

An experimental investigation was carried out to explore the possibility of using crystalline vinylidene fluoride copolymers as reinforcing agents for fluorosilicone elastomers. To achieve a fine dispersion of the fluoropolymer in the fluoroelastomer matrix, and to develop a strong adhesion between the two polymer phases, a compatibilisation procedure was used involving the pre-grafting of multi-functional free-radical crosslinking agents on the fluoropolymer chains before being blended with the fluorosilicone gum. Mixtures of Triallyl isocyanurate and Diallyl phthalate were found to be particularly useful for this purpose using γ -radiation to promote grafting reactions, which were enhanced by the addition of a small amount of benzoyl peroxide paste in the subsequent melt blending operation. The efficacy of this procedure was confirmed by differential scanning calorimetry and dynamic mechanical tests, showing a reduction in the degree of crystallinity and a depression of the melting point of the fluoropolymer phase and a small increase in glass transition temperature of the fluoroelastomer matrix. The peroxide cured blends exhibited large improvements in mechanical properties, both at room temperature and at 140 °C, and in large reductions in solvent absorption.