Preparation Of Cellulose Nanocrystals Catalyzed By Sulfonic Acid

Cellulose nanocrystals are cellulose treated by different methods to remove the nanocrystalline cellulose obtained by retaining the crystalline region in the amorphous region of cellulose.Compared with ordinary natural cellulose,it has been widely studied for its biocompatibility,biodegradability,reproducibility,low density,and adaptability to surface chemistry.In this paper,a series of cellulose nanocrystals,which are unmodified and modified,were prepared by using filter paper as raw material and different organic acids as acid decomposers,and the properties were compared with cellulose nanocrystals prepared from inorganic acid.In comparison,they were finally applied to the enhancement of mechanical properties of cellulose acetate and polylactic acid.In this paper,unmodified cellulose nanocrystals were prepared by using p-toluenesulfonic acid and methanesulfonic acid as acid decomposers and filter paper cellulose as raw materials.Through the preparation of the yield as a condition of investigation,a series of orthogonal and single factor experimental conditions were investigated to obtain cellulose nanocrystals with higher yield.At the same time,cellulose nanocrystals were also prepared by using inorganic acid-hydrochloric acid.They were tested in a series of performance tests.The cellulose nanocrystals prepared by the test showed that the reaction time of the cellulose nanocrystals was shorter than that of the inorganic acid-hydrochloric acid,and the yield was high and the performance was excellent.In this paper,cellulose acetate nanocrystals were prepared by filter paper cellulose as raw material,strong acid organic acid-p-toluenesulfonic acid as catalyst,acetic acid as dispersant and acetylation reagent.Through a series of orthogonal and single factor experimental conditions,cellulose acetate nanocrystals with different degrees of substitution were prepared.Through the comprehensive consideration of yield and degree of substitution,the conditions for preparing cellulose nanocrystals with higher yield and better substitution degree were obtained,and a series of performance tests were carried out on cellulose acetate nanocrystals prepared under better conditions.Comparison with cellulose nanocrystals prepared from inorganic acid-hydrochloric acid.The four cellulose nanocrystals prepared under the above conditions were used for the study of mechanical properties enhancement of cellulose acetate and polylactic acid,respectively.The results show that for cellulose acetate/cellulose nanocrystalline nanocomposites,the mechanical properties reach a maximum when the percentage of unmodified cellulose nanocrystals relative to cellulose acetate is 1 wt%.When the percentage of modified cellulose acetate nanocrystals relative to cellulose acetate is 2 wt%,the mechanical properties are better and the tensile strength is the largest.In the polylactic acid/cellulose nanocrystalline nanocomposite,when the percentage of cellulose acetate nanocrystals relative to polylactic acid is 3 wt%,the tensile strength reaches a maximum.When the percentage of other cellulose nanocrystals is 2 wt%,the tensile strength reaches a maximum.The elongation at break of polylactic acid/cellulose acetate nanocrystalline nanocomposites decreased first and then increased with the increase of cellulose acetate nanocrystal content,while the other three cellulose nanocrystals also showed this pattern.The effect of modified cellulose acetate nanocrystal substitution degree on the mechanical properties of nanocomposites was studied.The results show that the mechanical properties of cellulose acetate/cellulose acetate nanocrystalline nanocomposites increase first and then decrease with the increase of substitution degree.The effects of different plasticizers on the mechanical properties of cellulose acetate/cellulose nanocrystalline nanocomposites were investigated.The results showed that when a plasticizer was mixed with diethyl phthalate and dibutyl phthalate in a mass ratio of 1:1,the tensile strength and elongation at break reached a maximum at this time.