Two new polysiloxanes with condensed rings have been synthesized via Diels-Alder reaction of polyvinyl siloxane with phencyclone and acecyclone respectively. Using α-chlorona-phthalene as solvent
the said reactions proceeded smoothly at reflux temperature. The structures of these compounds have been characterized by 1H NMR
UV
IR spectra and GPC. Two compounds have better thermal stabilities than original polyvinyl siloxane. They were used as components of hot-air vulcanizable silicone rubbers. The resulting elastomers showed good mechanical properties (especially high modulus)and heat resistance.