Macromolecular non-releasing additives for commercial polyolefins

Four comonomers bearing a highly efficient phenolic antioxidant unit and different distance between the antioxidant moiety and the double bond have been prepared and tested in co-polymerization with ethylene by means of three selected metallocene based catalysts. The possibility to obtain a masterbach suitable for melt blending with commercial polyolefins has been evaluated by modifying: i) the structure of the functionalized comonomer, ii) the kind of catalyst, iii) the polymerization conditions. The pair rac-[Me 2Si-(2-Me-4,5-Benzlnd)2]ZrCl2 catalyst and comonomer with the longest spacer (8 methylene units) allowed the highest comonomer incorporation, while with rac-(EBTHI)ZrCl2 catalyst the highest polymerization activity was observed. TGA analysis has been carried out on some of the copolymers in order to investigate the influence of type and amount of the comonomer on their thermal stability and to test the efficiency of the antioxidant group both in nitrogen and oxygen atmosphere.