Study On The Preparation And Properties Of Water Absorbent Material By Blending Cellulose And Chitosan

At present,superabsorbent materials in the market are often reported to be lack of complete biodegradability and expensive.However,due to the low liquid absorption capacity of pure cellulose absorbent materials,how to meet the requirements of cost and biodegradability while ensuring the high water absorption performance is an urgent problem to be solved.Polymers based on polysaccharides/cellulose have attracted much attention due to their biocompatibility,low toxicity,biodegradability and low cost.Blending is an effective and convenient way to improve the properties of polymer materials.Chitosan and cellulose are the two most abundant biomass resources in the world,which conform to the concept of sustainable development and environmental friendly development.In this paper,based on cellulose?MCC?/chitosan?CS?,sodium periodate?Na IO₄?and chloroacetic acid?C₂H₃Cl O₂?were used to modify them respectively to obtain dialdehyde cellulose?damcc?and carboxymethyl chitosan?CMCS?.Then,sodium dodecyl sulfate?SDS?and neopentyl glycol diglycidyl ether?NGDE?were added respectively for reaction,and three kinds of water absorbent materials were prepared after vacuum freeze-drying.The effects of reaction factors?amount of DAMCC,amount of CMCS,amount of SDS,amount of NGDE,reaction temperature,p H value?on the properties of water absorbent materials were investigated;The characterization of microstructure by Fourier transform infrared spectroscopy?FTIR?,X-ray diffraction?XRD?,scanning electron microscopy?SEM?and thermogravimetric analysis?TGA?.?1?At first,the optimal ratio of water absorbent materials was discussed.When the content of damcc and CMCs was 1wt%,the ratio was 1:3,the reaction temperature was 60?,and the reaction time was 1 hour,the water absorbent materials had the best effect of absorbing deionized water,which could absorb 42g/g,and could also reach 15g/g in brine.It had good re expansion and degradability,and could reach 80%degradation rate in 120 days.It can be seen from the SEM of the water absorbing material that obvious holes can be seen in the water absorbing material,but the size and pore size of the holes limit the water absorbing performance.FTIR showed that MCC was successfully oxidized to DAMCC by sodium periodate,and further confirmed the Schiff base reaction between aldehyde group and amino group.?2?Secondly,in order to further improve the water absorption performance of the water absorbing material,SDS was added to the system to enhance the internal pore structure,the influence of stirring speed on the system was discussed,and the influence of SDS on the stability of the system and on various properties of the water absorbing material was further studied.The results show that when the content of damcc is 3wt%,the content of CMCS is 2wt%,and the content of SDS is 4wt%,the water absorption performance has been significantly improved.It can absorb 105g/g deionized water and 54g/g in brine.SEM characterizes the micro morphology of the water absorbing material.It can be seen that the water absorbing material has a highly porous structure.The pore diameter is in the range of 350-600?m and the geometry of the open pore,separated by the sheet wall and ultra-thin structure.FTIR showed that there was Schiff base reaction between aldehyde group and amino group,and SDS also participated in the reaction.XRD shows that in the foam gel,the interaction between SDS and Schiff base reaction completely destroys the crystal structure of MCC and leads to the decrease of CMCS crystallinity.?3?Finally,a new DAMCC/CMCS/SDS/NGDE foam absorbent material was synthesized by adding NGDE to the system.The composition and properties of NGDE blend foam absorbent material were discussed.When the DAMCC content was 3wt%,CMCS content was 2wt%,SDS content was 4wt%,NGDE content was4wt%,the foam system had excellent stability,and its water absorption effect was the highest,which could absorb 120g/g deionized water and reach the 62g/g in brine.After 192h,the water absorbing material can keep 50%of the water and 30%in brine.After one cycle of water absorption,the water absorption capacity decreased by about5%,but still maintained a high water absorption.After the third cycle,similar re expansion behavior did not further decline.It can be seen from the SEM picture that the surface morphology of the water absorbing material has changed obviously,and the pore diameter has increased,which fully confirmed the increase of NGDE and enhanced the water absorbing capacity,which laid a foundation for the re expansion performance and water retention performance of the water absorbing material.FTIR showed that the epoxy group on NGDE can participate in the reaction while the aldehyde group reacts with the amino group.To sum up,cellulose/chitosan blend water absorbent materials can give full play to their respective advantages,and can meet the needs of low cost and good degradation performance at the same time of high water absorption.This paper provides theoretical basis and practical basis for the research of superabsorbent materials.