Catalytic synthesis of polyaspartic acid in liquid phase and its scale inhibition performance

Polyaspartic acid was synthesized by catalytic polymerization with L-aspartic acid as raw material in the medium of propylene carbonate. The characteristics of the infrared spectrum and nuclear magnetic resonance spectrum of the product were analyzed, and its scale inhibition was examined. The influence of reaction condition on PASP productivity and the influence of PASP molecular weight on its calcium carbonate inhibition efficiency were investigated. The results showed that the optimal conditions of polymeric reaction were that the temperature was 165℃, the stoichiometric number(i.e.mole ratio) of catalyst to L-aspartic acid was 0.18 and the reaction time was 1 hour.Uuder the above conditions the viscosity average molecular weight of the product was about 10 000, and its performance of scale inhibiting to calcium carbonate reached to the best.