Highly Porous KGM Sponge By An Electrothermic Process At High Temperature

Sponge material has a special structure and excellent performance which has been widely used in various fields.Its demand is huge,and the growth rate is amazing.But with its increasing pollution to environment,as well as the shortage of raw oil,looking for a non-oil raw materials and developing biodegradable sponge material are imminent.Konjac glucomannan(KGM)is an abundant natural macromolecule resource,which can gel to form elastomer with a three-dimensional network structure similar to crosslinked polymer.It is a raw material for preparing biodegradable sponge material.However,there are few studies on KGM sponge material.At present,konjac sponges mainly produced by the steaming method are of large pore size and uneven pore size distribution,which is difficult to meet the requirements of sponge material.This paper presents a new method for preparing konjac sponge which is called electrothermal method.Inorganic blowing agent,organic blowing agent and compound blowing agent were combined with electrothermal method to explore the preparation conditions of gelation degree and foaming process.The structure and properties of products under different preparation process and blowing agents were analyzed to determine the effective formulation for the preparation of highly dense konjac sponges.The main results are as follows:(1)On the basis of analyzing the pyrolysis characteristics of KGM and blowing agent NaHCO3,konjac sponge KSS and KES were successfully prepared by steaming and high temperature method.The preparation method and effect of the amount of alkali,water and blowing agent in KES on the structure and properties of sponge were studied.Experiments show that the optimum formulation for inorganic electrothermal method is 0.6 g NaHCO3,60 mL H2O and 0.20 g Na2CO3 per 6 g KGM under 180℃.Compared with KSS,KES has a fine and uniform pore structure while its apparent density is decreased by 47.54%,and the porosity is increased by 90.52%.(2)The effects of different industrial blowing agents and dispersants on the preparation of foaming konjac were discussed.The process conditions of preparation of konjac sponge KHS with blowing agent H and dispersant sucrose ester were studied,and the structure and properties of KES and KHS were compared.The experimental results show that the optimum formulation of KHS is as follows:0.6 g H,58 mL H2O and 0.20 g Na2CO3 per 6 g KGM under 220℃.Under this condition,the apparent density of KHS is 43.61%lower than that of KES while its porosity is 77.22%.(3)The effect of combined blowing agents on preparation of foaming konjac was discussed.The process conditions of konjac sponge prepared by blowing agent HO1001(KHOS)were studied,and the structure and properties of KHS and KHOS were compared.The results show that the optimum formulation of KHOS is 0.6 g HO1001,60 mL H2O and 0.18 g Na2CO3 per 6 g KGM under 230℃.Under this condition,the porosity of KHOS is 82.23%,6.49%higher than that of KHS.