COMPARATIVE ANALYSIS OF TWO REACTIVE COMPATIBILIZATION ROUTES FOR POLYETHYLENE/POLYSTYRENE BLENDS

MARTINI, RAQUEL; BARBOSA, SILVIA

Donostia - San Sebastián

Simposio; 11th EUROPEAN SYMPOSIUM ON POLYMER BLENDS; 2012

In the last years, the most significant trend in the field of plastics is focusing on the material application. The compromise between economy and technical properties requirements is frequently reached, by development materials with predetermined properties, based on commodity plastics1. The blending technique provides an easy and efficient way to generate polymeric materials with novel and targeted properties as well as to achieve a reasonable set of properties from plastic blends. Even though most of the blends are immiscible, the direct blending causes weak interphases limiting the ability to develop materials that can compete with engineering polymers 2 (Paper Mónica). In this sense, the compatibilization processes are based on the improvement of adhesion between phases, the reduction of interfacial tension and the phase stabilization by the inhibition of droplet coalescence in subsequent manufacturing process. The compatibilization of a blend is carried out either by adding or producing in situ compatibilizer agent, which is located at the interphase, interacting with the phases by chain entanglement because of its physicochemical affinity to them. In this work, two ways to obtain polyethylene (PE)/ polystyrene (PS) blends by in situ copolymerization are presented. In the first case (reaction A), a physical blend is prepared from the homopolymers and then a copolymer is formed by alkylation reaction using AlCl3 as catalyst. In the second way (reaction B), the blend is made from PE homopolymer and styrene monomer, and performing the reaction by the same catalyst, producing the styrene polymerization and its grafting onto PE chains. The first reaction is performed in melting while the second one is carried out in solution using near critical n-heptane as reaction medium. The compatibilization effect, architecture of copolymer and mechanical properties are compared for the two kind of blending.