含长丙烯序列无规乙丙共聚物的合成与表征

用δ-TiCl₃-Et₂AlCl催化剂,以庚烷作溶剂,在单体C₃含量>60mol%的情况下,乙丙常压共聚可得到含长丙烯序列无规乙丙共聚物(LP-EPR)。其特性粘数〔η〕在2—3dl/g之间。影响〔η〕的主要因素是〔Al〕/〔Ti〕比、聚合温度和时间。共聚物的组成主要依赖单体C₃含量。通过庚烷萃取、红外、扭摆、x-射线衍射及相差显微镜等方法证明,在共聚物的无规乙丙分子链中含有全同聚丙烯(PP)序列,序列含量直接影响共聚物的结晶度、强度和硬度。

SYNTHESIS AND CHARACTERIZATION OF ETHYLENE-PROPYLENE COPOLYMERS WITH LONG C3-SEQUENCES

Random ethylene-propylene copolymers with statistically distributed long C₃-sequen-ces should have thermoplastic elastomeric properties as a result of the dual features in its molecular structure, contributing both to elasticity and PP higher temperature plasticity. In this work δ-TiCl₃-Et₂AlCl catalyst was used in an attempt to obtain E-P copolymers with isotactic PP sequences for the benefit of higher strength.The effect was studied of Ti],Al]/Ti], polymerization temperature and duration, and monomer composition on the polymerization yield, η], MWD and copolymer composition. Structure of the copolymers was proved by heptane-extraction, dynamic mechanical properties,IR spectra and x-ray diffraction studies. Crystallinity is the prime factor responsible for their strength, to which η] also contribates. High C₃ E-P copolymers are characterized by high crystallinity, strength and hardness and high elongation. A sample with C₃=79.8 mol% had a 300% modulus of 102 kg/cm² and a breaking strength of 135 kg/cm².