Study On The Preparation Of Nanocellulose And Its Modified Mask Substrate

Based on the idea of waste recycling principle and inspiration to reduce the waste of natural resources,this study is done by taking the spinning roller cotton from spinning factory as the raw material and extracting the nanocellulose by using the sulfuric acid hydrolysis method.In this study maximum yield of nanocellulose was explored by setting of different acid hydrolysis times to get the optimal process conditions and characterization of the nanocellulose was done.To evaluate the liquid carrying rate and water retention rate,masks substrate of cupro/tencel,rayon and cotton were coated with different concentration of nanocellulose.Similarly,the modified masks substrate were examined by evaluating weight,thickness,air and moisture permeability and mechanical properties after adding the nanocellulose.The study indicates:(1)The process conditions for the highest yield(64.3%)of obtaining nanocellulose prepared by acid hydrolysis was 60 min,acid hydrolysis temperature was 45 °C,sulfuric acid concentration for 64%,ultra sonication for 30 min and bath ratio was 1:10.(2)Characterization of nanocellulose: The size of nanocellulose evaluated by TEM image was recorded as 18-26 nm,the length as 140-200 nm,and the length to diameter ratio was found between 2 to 28,which shows that we got the nanocellulose whisker(CNC).The SEM image characterized the self-polymerization of the freeze-dried CNC into a two-dimensional sheet structure.FTIR characterization of the spinning roller cotton,pretreated spinning roller cotton and CNC reveal spectral peaks corresponding well by showing the characterization peaks as cellulose having no significant differences.XRD characterization reveals that the spinning roller cotton,after pretreatment and after sulfuric acid hydrolysis did not change the crystal structure of cellulose all types of samples have cellulose I crystal form and obviously crystallinity was increased after every step.The TGA characterizes the reduction of the thermal stability of the CNC,the initial degradation temperature was low,and the carbon residual rate was high.(3)Three kinds of mask substrate modified by different concentrations of CNC,the thickness and weight were increased of mask substrate.SEM image shows that the surface of the fiber was accompanied by some fine nanocellulose particles,and as the concentration of CNC increased,some fibers would bond to each other and the pore size became smaller.The three kinds of mask substrate have the same air and moisture permeability,and all of them shows characterization as cupro/tencel> rayon >cotton mask substrate.As the concentration of CNC increases,the pore size of the three masks substrate decrease,resulting in poor air and moisture permeability of the mask substrate.The longitudinal and transverse rupture strengths of the three masks substrate in the dry state are greater than those in the wet state,and the longitudinal and transverse rupture elongations in the wet state are greater than the longitudinal and transverse rupture elongations in the dry state.The longitudinal rupture strength in the dry and wet state is greater than the transverse rupture strength,and the transverse rupture elongation is greater than the longitudinal elongation at break.The three masks substrate was conformed according to the standard by examining the heat resistance,cold resistance and pH.(4)With the increase of CNC concentration,the liquid carrying rate of the three masks substrate increase for some concentration and then tend to decrease.The cupro/tencel mask substrate had the highest liquid carrying rate of 10.28 when the concentration of CNC was 2%,and the water retention was good when the concentration of CNC was 5%,but the preparation cost was high and the initial liquid carrying rate was low.The rayon mask substrate had the highest liquid carrying rate when the concentration of CNC was 1%,which was up to 11.27,the water retention was good at 5% CNC,but the initial liquid carrying rate was low.The pure cotton mask substrate had the highest liquid carrying rate when the concentration of CNC was 1%,which was up to 10.88,and at the same time had a good water retention.Considering cost,liquid carrying rate and water retention for the first 20 minutes,1%CNC modified cotton,rayon mask substrate and 2%CNC modified cupro/tencel mask substrate are preferred.