A New Method for Producing High Melt Strength Poly(propylene) with a Reactive Extrusion

Abstract

Summary: A new class of melt blend material was prepared by extruding a mixture of 3‐aminopropyltriethoxysilane (APTES), maleic anhydride‐grafted poly(propylene) (PP‐g‐MA) with different molecular weight and MA content and poly(propylene) powder produced with a TiCl3‐based catalyst (PP‐A). A suitable selection of PP‐g‐MA provided extremely high melt strength (MS) of resultant blend materials. Such a superior melt property was caused by the synergy between the present melt reaction and the higher molecular weight portion containing PP‐A. The gel content measurements of typical blend materials and PP‐g‐MA/APTES blends indicated that an excessive amount of inert PP suppresses the formation of gels. The reaction between PP‐g‐MA and APTES was then investigated by analyzing crystalline polymer fractions separated from the atactic PP/PP‐g‐MA/APTES and atactic PP/PP‐g‐MA blends. The FT‐IR analysis of the fractions revealed that the NH2 group in APTES readily reacts with MA grafted on PP and the reaction leads to the formation of imide linkage. Moreover, the GPC analysis of the fraction showed that higher molecular weight polymers were formed in the presence of APTES. Since a trace amount of water surely produces in the vicinity of active silyltriethoxy groups during the reactive extrusion, such polymers were formed by the condensation between hydrolyzed APTES‐grafted polymer chains. These results led us to the conclusion that long‐chain‐branched PP (LCB‐PP) was certainly produced and its formation is essential for the increase in MS of the present blend materials.Relationship between log(MS) and log(MFR) for PP/PP‐g‐MA/APTES and commercial PP resins.magnified imageRelationship between log(MS) and log(MFR) for PP/PP‐g‐MA/APTES and commercial PP resins.

A Method for Evaluating the Film-Blowing Processability of Biodegradable Materials

“…For instance, the resin with a lower melt flow rate possessed a higher melt strength, resulting in less sagging. Furthermore, a synergistic effect of long-chain branches and the presence of higher molecular weight fractions on melt strength has been observed …”

“…Furthermore, a synergistic effect of long-chain branches and the presence of higher molecular weight fractions on melt strength has been observed. 10 Extensional Viscosity. By controlling the molecular architecture of polyethylene (PE) chains, such as the number and distribution of olefinic comonomers and long-chain branches, as well as the MWD, the mechanical and rheological properties can be adjusted in a wide range.…”

New Reactive Formulations For Polypropylene Foams

“…As a result, different strategies have been developed for branching PP chains, the best known of which is the one starting from PP grafted with anhydride maleic (PP-g-MA). The PP-g-MA is then modified to obtain branching by reaction with amino-silane [5], amines [6], [7], or by ionic interactions [8].…”

“…[ 4 ] As a result, different strategies have been developed for branching PP chains, the best known of which is the one starting from PP grafted with anhydride maleic (PP‐g‐MA). The PP‐g‐MA is then modified to obtain branching by reaction with amino‐silane, [ 5 ] amines, [ 6,7 ] or by ionic interactions. [ 8 ] In our last paper, [ 9 ] we showed that the branched structure of polymer chains can be designed from a rheological criterion based on the notion of fractal behavior (coupling of relaxation modes), which polymer chains must have for nonlinear behavior (strain hardening).…”