Modifier 705 SiH-terminated polydimethyl siloxane Hanse Chemie Crosslinking / Coupling / Curing Agents >> Silane Silicones (Si) SEALANT ADHESIVE These are SiH-terminated polydimethyl siloxanes. Due to their difunctional structure, these products react with vinyl-functional silicone polymers not by curing, but by chain lengthening. The use of modifiers reduces the curing density and thus the hardness of the elastomer. Therefore, by using modifiers it is possible to attain relatively low Shore hardnesses even when using low-viscosity vinyl polymers. Our modifiers are thus used in formulations that need to be low-viscosity before curing and have a low Shore hardness after curing. This is difficult to achieve in conventional systems without chain extenders, since high-viscosity vinyl siloxanes are otherwise needed to achieve low hardness. SiH-terminated polydimethyl siloxanes. Used as chain extender to react with vinyl-functional silicone polymers. Reduces the curing density and the hardness of the elastomer.