STRUCTURE OF TRANS-1,4-POLYBUTADIENE SYNTHESIZED WITH A NEW CATALYST SYSTEM

Citation
E. Antipov et al., STRUCTURE OF TRANS-1,4-POLYBUTADIENE SYNTHESIZED WITH A NEW CATALYST SYSTEM, Journal of macromolecular science. Physics, B37(4), 1998, pp. 431-450
Citations number
32
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Polymer Sciences
ISSN journal
0022-2348
Volume
B37
Issue
4
Year of publication
1998
Pages
431 - 450
Database
ISI
SICI code
0022-2348(1998)B37:4<431:SOTSWA>2.0.ZU;2-N
Abstract
The structure, phase composition, and temperature behavior of two tran s-1,4-polybutadienes (TPBs) were studied by means of x-ray scattering and differential scanning calorimetry (DSC) techniques. The two sample s examined were (1) PB synthesized using an immobilized titanium-magne sium catalyst and (2) a random copolymer based on PB prepared with a h omogeneous vanadium-containing catalyst used as a reference material. It was found that the nascent structure of the first PB involves three phases: crystalline, mesomorphic (low-temperature form), and amorphou s. In the vicinity of 65 degrees C, a first-order phase transition occ urs. The system becomes biphasic and contains the high-temperature for m of the mesophase, as well as the amorphous phase, component. Above 1 65 degrees C, the polymer melts to form a single-phase isotropic melt with a structure typical of liquids. The lateral dimension of crystall ites reversibly changes at the crystal-mesophase transition. It is sug gested that during annealing of the mesophase formed by cooling of the isotropic melt, the chains acquire an extended conformation. Loss of regularity of the structure of macromolecules of TPB causes a reductio n of phase transition temperatures, an increase of the imperfection of the crystalline phase, and a contraction of the temperature range of existence of the mesophase.