Structural study of ethylene-acrylic acid and ester copolymers
In order to further investigate the differences in branched structure of ethylene-methyl acrylate copolymers obtained by free radical polymerization and coordination copolymerization,and to explain the essential reasons for the differences in branched structure,the melting point,melting index,molecular weight,polar monomer insertion rate,and micro chain structure of imported ethylene-acrylic acid and ester copolymers were characterized and analyzed in this study.The research results showed that,(1)The melting point range of ethylene-acrylic acid and ester copolymers was 64.1-98.4℃.The melting index range was 2.81-10.50 g/10 min.The average molecular weight(Mw)of EMA,EEA and EBA was almost around 200 000,and the molecular weight distribution(Mw/Mn)was less than 5.0.(2)The polar monomer MA in EMA copolymers coexisted on the polyethylene chain in two forms:the branched end and the main chain,with the branched end being the main form.MA did not have a continuous insertion structure in polyethylene chains,and was mainly inserted into polyethylene in a random form.(3)The imported EMA copolymer was obtained through high-temperature and high-pressure free radical polymerization,and the EMA copolymer chain contained butyl,pentyl,and long branches,while the EMA copolymer obtained through coordination polymerization contained short and long branches such as methyl,ethyl,and propyl.There were significant differences in the micro chain structure of EMA polymers obtained by two polymerization methods.
ethylene-acrylic acid and ester copolymerssemi-crystallizationstructurecharacterization
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