Surface acetylation of cellulose nanowhiskers and its reinforcing function in cellulose acetate

Cellulose nanowhiskers were prepared by sulfuric acid hydrolysis, then they were chemically modified by acetylation to obtain acetylated cellulose nanowhiskers(ACNW). The chemical and morphology structure of the ACNW were examined with Fourier transform infrared spectroscopy(FTIR), X-ray diffraction(XRD), transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS). ACNW with too low or too high degree substitute(DS) were not suitable for fillers in nanocomposites. When the DS of ACNW was 0.05, the acetylation modification limited only on the surface of the cellulose nanowhiskers, and the modified cellulose nanowhiskers preserved their original rod-like structure and high degree of crystallization. Cellulose acetate(CA) nanocomposites were prepared using ACNW as fillers by a casting/evaporation technique, and the effect of ACNW contents on the tensile properties of the CA matrix was studied. The tensile strength, Young's modulus, and strain at break of all CA nanocomposites exhibited simultaneous increase in comparison with neat CA matrix. The storage modulus of CA nanocomposites after temperature of glass transition(T_g) was higher than the neat CA matrix.