富含间规聚苯乙烯链段的乙烯/苯乙烯共聚物的合成及力学性能

Preparation and Mechanical Properties of Ethylene-Styrene Copolymers Containing Enriched Syndiotactic Styrene-Styrene Sequences

文中采用半夹芯型稀土金属配合物催化乙烯和苯乙烯共聚,合成了一系列具有不同共聚单体组成、富含间规聚苯乙烯链段的乙烯/苯乙烯共聚物。通过控制苯乙烯的投入量调控共聚物中乙烯的插入率,研究了乙烯插入率对共聚物熔点和力学性能的影响。结果表明,当乙烯插入率从9.6%升高到27.6%,共聚物中间规苯乙烯连续链段变短,熔点从256.3℃逐渐降低至241.4℃;当乙烯摩尔分数为72.9%时,表现出类似乙烯的熔点126.3℃。随着乙烯插入率的升高,材料的拉伸强度、弯曲强度逐渐降低,断裂伸长率、冲击强度逐渐升高,将乙烯插入间规聚苯乙烯链段有效改善了材料的脆性。当共聚物中乙烯摩尔分数为22.0%时,拉伸强度和冲击强度分别为54.3 MPa和20.4 kJ/m^(2)。文中合成的乙烯/苯乙烯共聚物强度大、熔点高,并具有一定的韧性。

A series of ethylene/styrene copolymers enriched syndiotactic styrene segments with different comonomers contents were synthesized via the copolymerization of ethylene and styrene catalyzed with a half sandwich rare earth metal complex.Ethylene contents in copolymers were controllable via changing the amount of styrene,and the effect of ethylene insertion towards melting temperature and mechanical properties of the copolymer was studied.The test results show that when the ethylene insertion rate increases from 9.6%to 27.6%,the continuous chain segments of syndiotactic styrene in the copolymer become shorter,and the melting point gradually decreases from 256.3℃to 241.4℃;when the ethylene content reaches 72.9%,a melting point of 126.3℃is observed,which is similar to that of ethylene.In addition,with the increase of ethylene content in the copolymer,the tensile strength and flexural strength of the material gradually decrease,and the elongation at break and impact strength gradually increase.The brittleness of the material is effectively improved by inserting ethylene into the syndiotactic polystyrene segments.When the ethylene content in the copolymer is 22.0%,the tensile strength and impact strength are 54.3 MPa and 20.4 kJ/m^(2),respectively.The ethylene/styrene copolymer synthesized in this paper has high strength,high melting point and certain toughness.