| For a long term,phosphate detergent builder represented by sodium tripolyphosphate (STPP) had been widely used as detergent builders in synthetic detergent industry because of its good detergent properties.However,its widespread application has caused eutrophication and the destruction of the ecologic environment,many countries have issued the laws and regulations to ban using STPP.Sodium polyacrylate and the acrylic copolymer are used to replace STPP as non-phosphorous detergent builders presently.They have good detergent properties,but their degradability is poor,so they also can cause environmental problems because of their long-term accumulation in environment.Polyaspartic acid (PASP) has good biodegradability,and its molecule contains carboxylic group with good chelating ability and dispersability,and preventing CaCO3deposition.Nevertheless,its chelating and dispersing capacity is not as good as the acrylic copolymer.Glutamic acid (GLU) molecule can enhanced chelating ability and dispersability which contains an amino group and two carboxylic acid groups. Therefore,the polyaspartic acid-glutamic acid grafted copolymer (PASP-GLU) was aminolysised by GLU and Polysuccinimide(PSI) on the alkaline conditions, in the study. The number of the carboxylic acid group in its side chain was increased, thus improve the chelating ability and dispersability of PASP. The specific research contents are as follows:First of all,polysuccinimide(PSI)was synthesized by thermal poly condensation of maleic anhydride and urea, then hydrolyzed to polyaspartic acid (PASP).The optimum technics conditions are as follows:in the polymerization process,the ratio of maleic anhydride with urea was1.0:0.7,and polymerized at180℃by1.00h,obtained polysuccinimide with the viscosity average molecular weight of1.00×104;in the hydrolysis process, hydrolysised at25℃by2h,keeping the pH of the reaction system was9.0. Under the optimum conditions,the chelating capacity,dispersancy and pH buffer ability of PASP are179.9mg CaCO3/g,100.9mg CaCO3/gand1.50mL HCI/g respectively. The structure of PSI and PASP were characterized by flourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (’H-NMR).The viscosity average molecular weight of PSI was determined by the limiting viscosity method.The polyaspartic acid-glutamic acid grafted copolymer (PASP-GLU) which had amide units in the backbone chain and carboxyl as pendant functional groups was synthesized by using PSI and GLU on the alkaline conditions. The optimum technics conditions are as follows:the ratio of PSI with GLU was1.0:1.8,ammonolysised at25℃by24h. Under the optimum conditions.the graft ratio of PASP-GLU was the maximum60.0%,and the chelating capacity,dispersancy and pH buffer ability of PASP-GLU are232.7mg CaCO3/g,108.9mgCaCO3/g and1.67mL HCI/g respectively,the detergent properties of PASP-GLU were superior to PASP.The structures and mass-average molecular weight (M(?)) of PASP-GLU were characterized by FTIRN、1H-NMR and gel filtration Chromatography (GFC).The results demonstrated that:the mass-average molecular weighs and polydispersity of PASP-GLU are between1.20×104-2.96×104g/mol and1.01-1.76respectively.The inlluence of the graft ratio on the detergent properties of PASP-GLU had been researched. As the grafting ratio increased,the chelating capacity of PASP-GLU significantly increased,but the dispersancy and pH buffer ability increased slightly. The thermal properties of and the crystallization of PASP-GLU were also been researched in this study.The biodegradability of PASP-GLU was studied by Shaking-Bottle Incubating Test.PASP-GLU is easy to biodegradable because of it has amide units with N heteroatom in the backbone chain,but the degradation rate become decreased with increasing the graliing ratio of PASP-GLU.It was found that PASP-GLU with60%grafting ratio is still biodegradable substance with accumulative biodegradability rate52%after21days... |
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