The Research On Synthesis And Properties Of Montmorillonite Composite Material

Montmorillonite and tapioca starch are abundant in Guang Xi province,for fully utilizing these two resources,montmorillonite composite materials were synthesized in this paper.Synthesis involved the following mainly:sodium modification of montmorillonite, esterifing tapioca starch with maleic anhydride,and grafting starch maleat ester with crylic acid.Furthermore,water absorption of composite material was measured.As additive of starch gels,the application of the composite material was also explored.The results of sodium modification of montmorillonite showed that the best conditions of turning Ca-montmorillonite into Na-montmorillonite were as following:the reaction temperature was 75℃,the reaction time was 6h,the dosage of sodium reagent was 6%,and the pH was 10.0.Under optimal conditions,the CEC of Na-montmorillonite was 103.31 mmol/100 g,at he same time,the expanded volume of Na-montmorillonite was 88.3 mL/g. The CEC of the preprocessing montmorillonite with microwave increased obviously.When ultrasonic were used in sodium modification of montmorillonite,the anti-precipitability of Na-montmorillonite was improved greatly.The results of the study on the synthesis of starch maleat ester with microwave showed that the optimal reaction conditions of synthesizing were as following:the weight of tapioca starch was 5.00 g,the molar ratio to starch of maleic anhydride was 0.45,the dosage of pyridine was 0.3,the reaction temperature was 100℃,and the reaction time was 5 min. Under these conditions,the substituent degree of ester was 0.189.The results of the study on the preparation of the composite showed that the best preparation condition was the following:the amount of crosslinking reagent was 0.02%,the amount of initiation was 0.047%,the amount of montmorillonite was 13.5%,the amount of starch maleat ester was 13.6%,and the neutralization degree of cryli1 acid was 80%, temperature was 60℃,reaction time was 5h.Under this condition,the composite material could absorb distill water as high as 746 g/g.Composite and starch could be able to form uniform gels.The experiment results showed that addition of composite material could improve the compressive strength of starch gels. Water retention property of composite could delay the hardening of starch gels since the losing of water.