Structure And Properties Of Cellulose Acetate Butyrate Prepared By Mechanical Activation-assisted Esterification And Its Application In Coating

With the development of traditional chemical industry,the problems of environmental pollution and energy shortage become more and more serious.Cellulose derivatives,a kind of renewable biomass macromolecule materials with the outstanding advantages of rich in resources,biodegradablity and non-pollution,have gradually attracted people's attention.Developing cellulose derivatives to replace the traditional industrial products is imperative.Cellulose acetate butyrate(CAB),which has good solubility,flexibility and film-forming properties,is an extremely important kind of cellulose derivatives.In this study,mechanical activation-assisted esterification(MAE)technology,which was developed by our research group,was used for the preparation of CAB.The effects of cellulose materials with different degree of polymerization(DP)and reaction time on the structure,film-forming properties and application performance in coating of CAB products were investigated.The research contents and results are as follows:(1)Using microcrystalline cellulose(DP?200)(MCC),cotton cellulose(DP?2500)(C1000),bagasse pulp fiber(DP?1300)(BPF),and cotton cellulose(DP?2500)(C2500)as raw materials,acetic anhydride and n-butyric acid as esterifying agents,concentrated sulfuric acid as catalyst,CABs with different reaction time were prepared by MAE technology.The cellulose materials and esterification products were characterized by means of SEM,1H-NMR,13C-NMR,FT-IR,XRD,and TGA.SEM showed that there had obvious difference in the surface morphologies of different cellulose materials,and significant changes were occurred in the surface morphologies of CABs compared with those of cellulose materials.1H-NMR analysis showed that the CAB prepared with MCC as raw material and the reaction time of 60 min had the highest degree of butyryl substitution.13C-NMR analysis showed that the butyryl and acetyl distribution of the CAB prepared by MAE were C-6>C-3>C-2 and C-3>C-2>C-6,respectively,while both the butyryl and acetyl distribution of the CAB prepared by traditional liquid phase esterification(TLPE)were C-3>C-2>C-6.FT-IR results showed that different cellulose materials were successfully esterified to produce CAB.XRD results showed that the crystallinity of MCC,C1000,BPF,and C2500 were 90.37,83.13,69.30,and 81.30%,respectively.The introduction of new groups by esterification reaction led to the generation of new diffraction peaks.TGA analysis showed that the thermal stability of CAB was lower than that of the corresponding cellulose material,and the CAB prepared with cotton cellulose as raw material and the reaction time of 60 min possessed the best thermal stability.(2)Using MAE-prepared CAB as film-former,the effects of casting solution,film-forming environment,cellulose material,and reaction time on the performances of CAB films were studied to determine the optimum film-forming conditions.Moreover,the film performances of the CAB prepared by different synthetic processses were compared.The results showed that the optimum film-forming conditions were:CAB prepared with cotton cellulose as raw material and the reaction time of 60 min as film-former,mixed solvent as casting solution,ABS plate as substrate,and film formation in open system.MAE-prepared CAB,TLPE-prepared CAB,and commercially available CAB 321-0.1 had no obvious difference in the film-forming performances.(3)Pearlescent coating was prepared using MAE-prepared CAB as film-former,pearl powder as paint,VAGF as film-forming additive,mixed solvent as coating solvent,and xylene as diluent.The effects of pigment/binder ratio,film-forming additive dosage,diluent dosage,and cellulose material and reaction time of CAB on the performances of coating film were investigated by testing their glossiness,hardness,resistance to drop paint,rub resistance,solvent resistance,water resistance,and cold and heat shock to confirm the best pearlescent coating formula.Then,performances of coating films prepared by MAE-prepared CAB,TLPE-prepared CAB,and commercially available CAB 321-0.1 were compared.The results showed that the best pearlescent coating formula was:CAB prepared with cotton cellulose as raw material and the reaction time of 60 min as film-former,pigment/binder ratio of 7%,film-forming additive dosage of 2.5%,and diluent dosage of 20%.Under the best pearlescent coating formula,MAE-prepared CAB,TLPE-prepared CAB,and CAB 321-0.1 had no obvious difference in performances of coating film.It indicates that using MAE-prepared CAB as film-former in pearlescent coating has exhibited good practical applications.