Effect of dimethyl formamide in the synthesis of linear low density polyethylene on its rheological properties
- 作者：Sara Shahidi anvar ; Naghmeh Fazeli<sup> ; sup><sup>N.Fazeli@srbiau.ac.irsup> ; Milad Mehranpour
- 关键词：Polyethylene ; Ziegler&ndash ; Natta polymerization ; Rheology ; Viscosity ; Short chain branching (SCB)
- 刊名：Polymer Testing
- 出版年：2012
- 期刊代码：143_01429418
- 类别：et
- 出版时间：August, 2012
- 卷：31
- 期：5
- 页码：671-676
- 文件大小：558 K
摘要
Different amounts of dimethyl formamide (DMF) as an external electron donor have been used for the synthesis of LLDPE samples with different branch structure via gas phase polymerization of ethylene/1-butene copolymer with TiCl<sub>4sub>/MgCl<sub>2sub> and triethyl aluminum catalyst system. Then, the effect of DMF (and consequently branch structure) on rheological properties of the synthesized samples, such as complex viscosity, MFI, loss modulus, storage modulus, transition point, power law index and Cole-Cole plot, have been studied. According to the obtained results, all of the curves relating the rheological properties of the samples to the ratio of DMF/Ti passed through an extremum point at about DMF/Ti聽=聽0.25, which can be attributed to the changing of branch characteristic of the samples from heterogeneous viscous liquid-like structure to a uniform elastic three dimensional one at this extremum point.