Study On The Stability Of Natural Cellulose In TBAH Aqueous Solution And The Mechanical Properties Of Regenerated Cellulose Film

Cellulose is the most productive and widely sourced biomass polymer material on earth.Cellulose is favored for its advantages of renewable,biodegradable,good biocompatibility,and low cost;in addition,cellulose materials have good application prospects in the fields of food medical packaging and composite materials.Because the cellulose structure contains high-density hydroxyl groups,a complex and abundant hydrogen bond network is formed within and between molecules,which causes the cellulose to be infusible and difficult to dissolve,which brings huge challenges to processing and molding.Dissolution and regeneration are the key to obtaining high-performance cellulosic materials,and therefore are the research focus and hotspot in the field of cellulosic materials;the storage stability of cellulosic solutions is the basis for achieving high-efficiency and environmentally friendly applications.Tetra-butylammonium hydroxide(TBAH),as a new type of cellulose solvent system,has received great attention from researchers in recent years,but there is no systematic research on its storage stability and regeneration bath system and other related academic issues.Report.Based on this,based on the research on the dissolution performance of TBAH/H₂O and its mixed solvent system with dimethyl sulfoxide(DMSO)and urea(Urea)in the early stage of the research group,this paper analyzes the cellulose at different temperatures.In-depth research has been carried out on the changes in the properties of the solution and the influence of the polarity of the regeneration bath on the mechanical properties of the regenerated cellulose materials.Specific research work and main research results include:(1)Comparative study of the dissolution of cellulose in TBAH/H₂O,TBAH/H₂O/DMSO and TBAH/H₂O/Urea solvent systems and the viscosity change during subsequent placement,and the the problem of inter-diffusion with solutes,it is found that the solvent will continue to dissolve the cellulose during the placement process and cause the viscosity of the solution to slowly decrease.Taking the TBAH/H₂O/DMSO solvent system as an example,the changes in the viscosity and degree of polymerization of the cellulose solution at different storage temperatures were studied.It was found that after the cellulose solution was placed for a certain period of time,due to the strong alkalinity and strong dissolving ability of the solvent,the cellulose is degraded;the cellulose solution placed at a constant temperature of 40°C is regularly sampled and scraped to test its mechanical properties.It is found that as the storage time is extended to 176 h,the tensile strength of the cellulose film sample gradually increases from 119 MPa After reaching 147 MPa,it was reduced to 45 MPa.(2)Using Gaussian software to simulate the chemical shifts of different hydroxyl peaks(free hydroxyl groups,intramolecular hydrogen bonds,extramolecular hydrogen bonds)in the infrared spectrum of the cellulose molecular chain,it is found that the formation of hydrogen bonds will promote the absorption of infrared spectra.Redshift.The effects of different polarity regeneration baths on the morphology and structure of regenerated cellulose were studied.The lower the polarity of the regeneration bath,the easier it is to form a sparse lamellar structure;In the lower regeneration medium,cellulose tends to form intermolecular hydrogen bonds.(3)Using alcohol solvent as the regeneration medium,the polarity of the regeneration bath is changed by increasing the carbon number on the carbon chain(C=n(n=1,2,3...)),and the cellulose film is regenerated in different regeneration baths.Carry out structural and mechanical performance characterization.It is found that in the alcohol regeneration bath,as the carbon chain of linear alcohol molecules increases,the proportion of hydrogen bonds between cellulose molecules first increases and then decreases.When the carbon chain is 6(C-6,that is,n-hexanol),the hydrogen bonds the percentage is the highest,and the elongation at break of recycled materials also shows a similar trend.At this time,the proportion of hydrogen bonds between cellulose molecules O(6)H???O'(2)(010)is larger than that of other regeneration baths.The range is increased,and the elongation at break is 29.16 times the lowest,reaching 41.11%.