Silicone-based release agents for polyurethane: a general assessment of the importance of interface structure and morphology

This paper describes an evaluation of various silicone-based materials as mould release agents for a polyurethane/smooth stainless steel interface. The release properties of these materials have been characterized by the use of a blister test and data are provided for peeling energies over a range of peeling velocities. Three types of silicone system were studied: silicone fluid, silicone resin, and a combination of fluids and resins. All these materials provide a reduction in the peeling work compared with a virgin interface although some systems are significantly more effective than others in reducing the peeling work. The lowest adhesion energies were obtained with certain combinations of per-methyl silicone resins and silicone fluids. In these systems there is indirect evidence for the formation of friable, marginally bonded particle based structures which are sufficiently durable to . withstand the polymerization process but are readily ruptured or fractured during the subsequent peeling of interface.