Study On PVA Composite Films Enhanced By Cellulose Nanofibrils/Graphene Oxide

The properties of polymer nanocomposite materials can be effectively improved by the inclusion of nanoscale fillers.With the development of nanotechnology,novel functional nanocomposites have been emerging in recent years.In this paper,the modified TEMPO-oxidation method was used to prepare hardwood nanofibrils.The morphology,size,carboxyl content and contact angle of the cellulose were investigated with the increase of oxidation degree during the oxidation process.The results indicated that nanofibrils of hardwood cellulose were prepared successfully by modified TEMPO-oxidation.The length of nanofibrils was 400 nm-500 nm and it was reduced with rising oxidation degree.Graphene oxide(GO)has been considered as a promising filler material in polymeric nanocomposites owing to its satisfactory dispersibility and large surface area.In this work,nanofibrils(NCC)and GO were taken as the matrix and nanofillers,respectively,to fabricate ultraviolet(UV)shielding composite films.Results showed that GO sheets were well dispersed throughout the NCC matrix,proving homogeneous structure.Moreover,NCC/GO composite films offered an improved high energy light-shielding capacity when compared to pristine NCC films.Particularly for ultraviolet(UV),the UV-shielding capacity was up to 90%.It was found that the water contact angle values of the NCC/GO composite films(G:C-1:2)was 81.7 °,and water absorption dropped by 43%;the weight loss around 500? was 62%,suggesting a good water resistance and higher thermal stability.In addition,the Young's modulus and tensile strength of the NCC/GO composite films(G:C-1:2)were significantly improved by 110.8%and 217.8%,respectively.Thus these results revealed that NCC/GO composite films have potential to be used as UV-protective materials for packing biomedical,pharmaceutical,and food products.In order to decrease cost,the improvement of properties of polyvinyl alcohol(PVA)with NCC/GO as composite fillers was also studied in this paper.With 5 wt%dosage of NCC and GO,the Ultraviolet shielding performance of the PVA/NCC/GO composite films was more than 90%.The tensile strength and Young's modulus of the PVA/NCC/GO composite membrane(G:C-1:2)was increased by 74.5%and 278.0%,respectively,and the water absorption was dropped by 59%,in comparison with the pure PVA membrane.Moreover,the two nanofillers NCC and GO in the composite films had a synergistic effect.In a word,PVA/NCC/GO composite films possess excellent Ultraviolet shielding properties,thermal stability,mechanical properties,and water resistance.Meanwhile,the materials are green,safe,and degradable.It is a promising packaging material in need of UV shielding performance for food,biological,pharmaceutical products.The synergistic effect between nano fillers of NCC and GO has a significant effect on the modification of the composite films,which provide a novel method for the development of multifunctional nanocomposites.