| In recent years,synthetic foaming materials have been widely used,but a series of environmental problems have occurred due to their indiscriminate discarding and abuse.Foaming materials based on plant fibers have biodegradability,recyclability and abundance,and have the potential to replace traditional plastic analogs.The development and application of biomass foam materials can improve the utilization rate of resources,further alleviate the pressure of resource shortage,but also meet the demand of the market,has great economic and social significance.In this paper,the foaming material was prepared with biomass straw as raw material through different modification methods and foaming process,and its hydrophobic performance was studied.The main research contents are as follows:(1)Cellulose foam material: when alkali treatment with 2%(mass fraction)Na OH solution(straw: solution =1 g: 40 m L),reaction at 100 ℃ for 3 h,the best effect.When the ratio of sodium bicarbonate to azodiisobutyronitrile is 1:2,the amount of calcium carbonate is 2 g,the amount of acrylamide is 4 g,the amount of TW-80 is 3 g,and the amount of PVA is 2 g,the overall apparent effect of foaming material is the best,and the load is 4502 N at 30% strain.After impregnation with PDMS,the cellulose foamed material was transformed into surface hydrophobic material with porosity of 83.84%and average pore size of 10.94 μm,and contact Angle of 122°.(2)Modification of cellulose foaming material by silane coupling agent: the silane coupling agent KH570 was used for organic modification of cellulose.The maximum yield of cellulose was 222.9% after the reaction at 90 ℃ for 24 h,and the porosity,average pore size and apparent density were 75.91%,4.81 μm and 1.36 g/m L after freeze drying.On the basis of modification of silane coupling agent,the hydrophobic adamantane molecule was introduced to provide the base material as the follow-up foaming material.The maximum yield of cellulose and diamondoyl chloride(mass ratio1:1)was 82.2% and the contact Angle was 124.7° at 60 ℃ for 48 h.The two modified contact angles were 113° and 141°,respectively,with hydrophobic properties.The porosity of the material reached 73.01% after freeze drying and foaming with 2%sodium alginate solution.The average pore size was 5.83 μm and the apparent density was 1.19 g/m L.(3)graft copolymerization modification of cellulose foam material: with potassium persulfate as initiator,using methyl methacrylate grafted,characterization of its morphology structure system,and the dosage of the catalyst and monomer is discussed,the results showed that potassium sulfate used in 0.5 g,7.5 m L can be modified when successful,methyl methacrylate and yield up to 97.6%.Contact Angle is 121.1°,with hydrophobic performance.The porosity of the material reached 96.5%,the average pore size was 53.34 μm,and the apparent density was 2.03 g/m L after freeze drying with 2% carboxymethyl cellulose solution.(4)Esterification modified cellulose foam material: With acetic anhydride as the surface modifier and 4-dimethylaminopyridine as the catalyst,cellulose acetate was successfully prepared at 110 ℃ for 2.5 h reaction,contact Angle of 145°,freeze drying foam with 2% carboxymethyl cellulose solution,porosity of the foam material reached92.51%.The average pore size was 30.85 μm and the apparent density was 1.57 g/m L.After soaking,after 10 cycles of compression,the foaming material still retains its original appearance and has excellent resilience.Cellulose can be obtained by chemical foaming process with high hardness and good compression resistance.The foam material with light weight and good resilience was prepared by freeze-drying.Cellulose modified by methylsilylation,graft copolymerization and esterification has different hydrophobic properties.The maximum contact Angle of esterification modified cellulose is 145°,and the freeze drying foam material has the largest porosity(92.51%),the smallest pore size(30.85μm),good water resistance and the best wet foam resilience. |
PDF Full Text Request