a. Molecular structure Silicone resins are prepared by condensation of silanes, e.g. RSi(OH)3. The R groups are aliphatic or aromatic radicals. b. Modification Silicone resins are modified with alkyl (aliphatic groups) and/or aryl radicals (aromatic groups). A phenyl radical increases the elasticity and gloss. The alkyl groups incorporated in the resin are mostly methyl groups. Longer radicals, e.g., propyl or butyl groups, are rarely used. The resins modified with methyl groups have reduced elasticity, inferior pigmenting properties and inferior compatibility with combination binders. The heat resistance of pure ...