Polyethylene/Styrene Copolymerization Reaction under High Temperature-High Pressure Conditions

摘要

Copolymers have found applications in diverse fields like adhesives, paint or coating materials, emulsifiers to molding materials, and biomedical applications. Other important area of application is its use as compatibilizing agents in blends. In this work, copolymerization of styrene and polyethylene (PE) was carried out in high pressure-high temperature n-heptane medium. The reaction was a Friedel-Crafts alkylation and the catalyst used was aluminum chloride (AICI3). By this reaction, a hydrocarbon chain can be chemically bonded to the styrene ring through an aromatic electrophilic substitution. The principal advantage of this method of reaction is that the high molecular weight polyethylene, is solubilized by alkanes at near critical conditions, and then, the polymer chains are more available to react than in a melt blend The reaction occurrence was corroborated using Fourier transform infrared spectroscopy (FTIR), after a careful phase separation of the reaction product by selective soxhlet extraction using tetrahydrofuran (THF) Besides of FTIR, differential scanning calorimetry (DSC), size exclusion chromatography (SEC), scanning electron microscopy (SEM) were the techniques used for characterization of the reaction products and quantification of the polystyrene copolymerized,. The effect of the amount of catalyst added was studied varying the content from 1 to 5-wt% of AICI3 at the same PE/styrene relation.