Preparation Of Chitosan Grafted Bacterial Cellulose And Its Application In Sanitary Products

Nanocellulose is widely used in medical service,food packaging,papermaking and other industries because of its excellent mechanical properties,surface properties and biocompatibility.Bacterial cellulose(BC)is a kind of biosynthesized natural cellulose with a diameter of about several tens of nanometers and does not contain hemicellulose,lignin and other impurities,so it is an ideal raw material for the preparation of nanocellulose.This study aims to isolate cellulose nanofibers from BC granules,endow them with bacteriostasis property,and apply them to surface materials of sanitary products,thereby promoting the research and development of functional sanitary products.Firstly,the crystalline structure of BC was explored,and BC particles were dispersed by blender,ultrasonication and nano-grinder,and different methods were used to evaluate the dispersion effect.The results showed that BC was cellulose I structure with a crystallinity of 73.38%.When BC was digested 25000 r by blender and then followed by ultrasonication at 60%amplitude for 20 minutes,or nano-grinder treatment,the BC dispersion was uniform and continuous with high dispersity,and the membrane uniformity was good.Visual observation and degree of dispersion method were simple and intuitive in evaluating dispersion effect,while Zeta potential,charge density and turbidity method can quantify the results.The results of fiber quality and morphology analysis showed that ultrasonication and nano-grinder had the effect of both peeling and cutting on BC fiber,but the cutting effect was greater than peeling for ultrasonication,while nano-grinder was just the opposite.Secondly,chitosan was grafted onto BC by Schiff base reaction,and then obtained the nano-sized fibrils by ultrasonic dispersion process.The results showed that the maximum grafting amount of chitosan was 12.38%when 0.15 mol/L sodium periodate was used to react at 50? for 2 h,and FT-IR and SEM confirmed the reaction.From the dispersibility and stability behavior research,the suspension containing chitosan was more uniform and showed better acid and temperature stability.It can also be observed in SEM and TEM images that the bacterial cellulose was dispersed into single ones.The bacteriostasis experiment showed that BC-CS had certain bacteriostasis activity and the higher the content of chitosan,the better the bacteriostasis performance.Finally,BC-CS dispersant was sprayed onto polypropylene nonwoven fabric to obtain the single-sided hydrophilic modified nonwoven fabric,and then it was assembled into sanitary products.The results showed that the comprehensive properties of composite nonwoven was best when the layer-by-layer deposition was applied to spray five layers and concentration of spraying solution was 0.44%.SEM images showed that BC fibers were intertwined on the surface of PP fibers.The presence of oxygen and nitrogen in EDS layered images further confirmed the successful combination of BC-CS and PP nonwovens.In addition,IR analysis showed that BC-CS fibers and non-woven fabrics only combined by physical interaction,and there was no chemical reaction.When assembled into a sanitary product,it exhibited good water absorption,anti-return percolation and bacteriostasis properties.