Synthesis of Oligopropylene Macromonomer and Investigation of Its Binary Copolymerization with Maleic Anhydride

Abstract

The destruction of polypropylene (PP) at low pressure in a nitrogen flow with the aim of preparation of oligopropylene macromonomer (OPMM) was carried out. The influence of various process factors (temperature, pressure) on the yield of the purposeful product was studied and the optimal parameters of thermal destruction of polypropylene were determined. It was shown that the highest yield is achieved at temperature of 340°C and pressure of 500 mmHg. Unlike the known ones, in the proposed method, the molecular weight (MW) of the macromonomer can be simultaneously adjusted with varying temperature and pressure. It was shown that timely removal of the reaction product from the reactor favors the prevention of the secondary reactions (decomposition, branching) and preparation of the macromonomer with the narrow molecular weight distribution. The radical copolymerization reaction of maleic anhydride (MA) with oligopropylene macromonomer was carried out, the regularities of the copolymerization reaction, the composition and structure of the obtained products were revealed. The the relative activity values of the oligopropylene macromonomer (r₁ = 0.052) and maleic anhydride (r₂ = 0.0035) during their copolymerization were determined by the Fineman-Ross method. The microstructure parameters were calculated for samples of the copolymer of the oligopropylene macromonomer with maleic anhydride obtained under various conditions. It was detected that during the copolymerization of the macromonomer polypropylene+maleic anhydride pair in the presence of benzoyl peroxide (BP), the copolymer macromolecules of an alternative structure are formed. Depending on the copolymerization conditions, the average molecular weights of the obtained copolymers are oscillated within the range of 12970–19750 (M_w) and 8470–14500 (М_n).