Structure And Properties Of High Melt Strength Polypropylene

The Polypropylene is a conventional polymer having many desirable and beneficial properties. Because of catalyzed by Ziegler-Natta catalyst , Polypropylene only has linear structure, which induced low melt strength and bad resistance to sagging. Thus it has a variety of melt processing shortcomings, including the onset of edge weave during high speed extrusion coating of paper or other substrates, sheet sag and local thinning in melt thermoforming and flow instabilities in co-extrusion of laminate structure. This research provided a process for converting the linear Polypropylene into the Polypropylene having an amount of long chain branches of propylene units. By sensitizing irradiation, the melt strength of the conventional Polypropylene has been increased greatly.Influence of the Polypropylene type, sensitizer type and content , irradiation dose on the melt strength, gel fraction and melt flow rate was studied. The results show that high melt strength Polypropylene was got using T36F resin with 0.4～1% 1,4 butanediol diacrylate as sensitizer and 0.4～1.5kGy radiation dose.Many ways was used to study the relationship of the structure and properties of sensitizing irradiated Polypropylene with different sensitizer content. The influence of sensitizing irradiation on microstructure and properties of crystallization, mechanical, processing and rheology was deeply analyzed.