STRUCTURE AND MESOMORPHISM OF 1,4-TRANS-P OLYBUTADIENE SYNTHESIZED ONA SUPPORTED TITANIUM-MAGNESIUM CATALYST

The structure, phase composition, and temperature behavior of two 1,4- trans-polybutadiene samples were examined by means of X-ray scattering and DSC. The two examined samples were the PB synthesized on a suppor ted titanium-magnesium catalyst and that obtained on a homogeneous van adium-containing catalyst. It was found that the nascent structure of the first PB involves three phases, viz., crystalline, mesomorphic, an d amorphous. In the temperature interval between 20 and 85 degrees C, a first-order phase transition occurs, as a result of which the system becomes two-phase and contains the high-temperature form of the mesop hase and the amorphous phase component. Above 165 degrees C, the polym er melts to form a single-phase isotropic melt with the structure typi cal of liquid systems. The lateral dimension of crystallites reversibl y changes on crystal-mesophase transition. It was suggested that, duri ng the annealing of mesophase formed by cooling of the isotropic melt, the chains acquire an extended conformation. Infringement of regulari ty of the structure of the macromolecules of PB reduces the phase tran sition temperatures, increases the imperfection of crystalline phase, and contracts the temperature region for the existence of mesophase.