THE REVERSIBLE NETWORK FORMATION IN POLYDIMETHYLSILOXANES WITH SIDE CARBOXYL GROUPS

The peculiarities of the structurisation of polydimethylsiloxane with carboxyl side groups are investigated by studying its viscosity, elasticity and thermomechanical behaviour over a large temperature interval. The structurisation exhibited in the transition from initial liquid to elastomeric state is shown to be thermoreversible. It occurs more intensively as temperature increases. The cooling of the polymer to room temperature leads to the liquefaction of the elastomer proceeding over a long time; this time depending on the temperature and the length of time of heating. The reasons for these peculiarities lie in the relation between intra- and intermolecular interactions between COOH-groups and the specific changes of polydimethylsiloxane conformations with temperature.