Dynamic Mechanical Thermal Analysis and Rheological Properties of Synthesized Polypropylene Reactor Blends Using Homogeneous Binary Metallocene Catalyst

ABSTRACT

A homogenous binary metallocene catalytic system comprising of isospecific rac-Me₂Si(2-Me-4-Ph In)₂ZrCl₂(I) producing high molecular weight isotactic polypropylene and oscillating (2-Ph In)₂ZrCl₂(II) precursor producing low isotactic elastomer polypropylene at three varying molar ratios of two types of catalysts was used to synthesize polypropylene reactor blends. Dynamic mechanical thermal analysis and rheological properties along with molecular weight of synthesized polypropylene reactor blends were studied and correlations among these properties were established. It was found that molar ratio of catalysts is a significant factor in determination of molecular weight and its distribution. The produced polymers with unimodal molecular weight distribution showed intermediate modulus during dynamic mechanical thermal experiment, while the ones with bimodal molecular weight distribution exhibited a kind of phase separation at low temperature. Depending on strength of the developed structures, determined by the presence of interfacial connectors, the modulus could be adjusted. Origins of other types of relaxations and their differences for each type of the developed products were discussed in detail. From rheological results and particularly the relaxation curves, the characteristics of the chain structure of the synthesized reactor blends could be resolved. It was revealed that one of the synthesized polymers had long chain branches unlike the rest of the samples having linear chain structure.

GRAPHICAL ABSTRACT

KEYWORDS:

• Binary metallocene catalyst
• dynamic mechanical thermal analysis
• polypropylene
• reactor blend
• rheology