Preparation Of Long Chain Branching Polypropylene

Polypropylene is a plastic used generally, but polypropylene with highly linear chains resulted in lower melt strength on melt. Thus, it restricts its application in processes such as thermoforming, film blowing, blow molding, and foaming. Long chain branching polypropylene is most valid measure to improve melt strength. The article summarizes the development of investigation in preparation of long chain branching by modified linear polypropylene. At the same time the article give a new way to synthesis long chain branching polypropylene. By this way, a series of long chain branching polypropylene with different structure were prepare. Testing structure and performance of polymer is approve long chain branching. And clarify elementarily reason of form of long chain branching. 1 Design and Synthesis of Long Chain Branched Polypropylene1) Blending linear and long chain branching polypropylene prepared high melt strength polypropylene.Blend of long chain branching polypropylene attained by catalyzing MAO and linear polypropylene control molecular weight, degree of branching.2) Synthesize long chain branching polypropylene with melt extrusionPolypropylenes with long chain branches were obtained using reactive extrusion in the presence of peroxide, a polyfunctional acrylate monomer and a co-reactant: a sulfide compound such as thiuram disulfide. By thermal decomposition, the thiuram disulfide gives two dithiocar- bamate radicals. These radicals can be reacted with the macroradical PP, and this reaction is reversible. They induce a decrease in the instantaneous concentration of free radicals, favor the branching, and thus limit the effect of the P-scission. The long chain branches structure was confirmed by dynamic viscoelastic measurements and thermal analysis. Futhermore, we implement this reaction with intermeshing corotating twin screw extruder and Haake RHEOCORD90-Haake3) Structure and Properties of Long Chain Branched Polypropylene...