Ethylene polymerization to branched thermoplastic elastomers through proper activation of heterogeneous nickel (II) α-diimine complex and thermal drawing process

• Published in: Polymer (Guilford) 2019-09, Vol.179, p.121660, Article 121660
• Main Authors: Manteghi, Amin, Arabi, Hassan, Farhadi, Ali
• Format: Article
• Language: English
• Subjects: Ethylene polymerization; Thermal drawing; Thermoplastic elastomer
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2019.121660

Ethylene polymerization with heterogeneous nickel (II) α-diimine complex, covalently attached to silica, under various conditions revealed effective control over polymer structure and activity. NMR, WAXD, thermal and mechanical characterization techniques provide the relationship between crystallinity and elastic properties and polymer microstructure. Catalytic activation with high ethylaluminium sesquichloride (EASC) amount (Al/Ni = 1500 and 2000) can improve productivity and induce long-chain branch formation. Increasing temperature, changes polyethylene behavior from properties characteristics of thermoplastics toward elastomers by only ethylene polymerization. Moreover, uniaxial stretching at melting, crystallization and onset of crystallization temperatures showed to have significant impact on crystallization behavior and mechanical properties enhancement. In particular, drawing at Tc resulted in formation of interlamellar crystallites followed by improving stress-at-break up to 200% and crystalline index to 80%. [Display omitted] •Elastomeric to thermoplastic PE through modulation of polymerization conditions.•PE branch content and distribution influence thermal and mechanical properties.•Improved productivity and long-chain branch content at Al/Ni = 1500 and 2000.•Stretching at Tc, Tm and Tonset affect crystallization and mechanical properties.•Thermal drawing at Tc improve Xc upon formation of interlamellar crystallites.