Modification And Performance Of Polyaspartic Acid

Poly aspartic acid is a kind of biodegradable environmentally friendly scale inhibitor. For its not perfect dispersant ability, the use of the inhibitor is confined. Based on the study of poly aspartic acid. Its graft copolymers were synthesized by introducing other function groups such as hydroxy and sulfonic.In this paper, Aspartic acid glutamic and acid copolymer (PAG) was synthesized by condensation polymerization of aspartic acid and glutamic acid monomer. The effect of The proportion of different graft on the scale inhibition rate were studied. It showed that the optimal conditions are as follows:reaction temperature at 190℃,reaction time at 2 hours and ASP:GLU=7:3.PAG Sulfomic acid and ethanolamine were used to synthesize PAG graft copolymers.The performance of the graft copolymers were studied by static scale inhibition test and specimen method. The results show that PAG graft copolymers are environmentally friendly scale and corrosion inhibitors. They have outstanding performance of scale inhibition on calcium phosphate. Scale inhibition rate of PAG graft copolymer containing hydroxyl on calcium phosphate is 87.23% with calcium dosage of 120mg/L and the mole ratio of hydroxyl and PAG is 0.6.While the scale inhibition rate of poly aspartic acid is only 1.5%.When the mole ratio of hydroxyl and PAG is 1, the performance of corrosion inhibition is the best. Corrosion inhibition rate of PAG graft copolymer containing hydroxyl is 76.23% with 4 days under temperature of 50℃and the mole ratio of hydroxyl and PAG is 1. When the mole ratio of sulfonic and PAG is 1,the performance of dispersing calcium phosphate is the best. The scale inhibition rate is 89.65%.The influence of PAG containing hydroxy and PAG containing sulfonic on calcium carbonate crystal and the scale inhibition mechanism were studied. It showed that calcium carbonate crystal were split and distorted obviously by poly aspartic acid graft copolymers. Calcium carbonate crystal was more dispersive. PAG containing hydroxy in the metal surface adsorption film, slow metal corrosion.