Preparation And Properties Of NCC/GO/PVA Composite Films

Polyvinyl alcohol (PVA) has excellent biodegradability, film-forming property, printability, solubility and environmental friendliness, and is one kind of packaging materials with huge potential application. PVA is widely used in packaging, bio-medical and other industries. However, there are a large number of hydroxyl groups and hydrogen bonds in the molecular chain of polyvinyl alcohol, water resistance, mechanical properties and barrier properties of biodegradable materials, which are prepared with polyvinyl alcohol as raw materials, cannot meet the requirements. Therefore, enhancing the mechanical properties, barrier properties and water resistance becomes major problems.In this thesis, well-dispersed nano-cellulose (NCC) and graphene oxide (GO) were prepared, then mixed with polyvinyl alcohol (PVA) as reinforcements. The nano-cellulose/polyvinyl alcohol (NCC/PVA) and graphene oxide/polyvinyl alcohol (GO/PVA) binary composite films were prepared by casting method with different mass fraction. The microstructures and morphology of composite films were investigated with Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The barrier properties, mechanical properties, water resistance were studied. The composite film with a better comprehensive performances was selected as reference in preparing grapheme oxide/nano-cellulose/polyvinyl alcohol (NCC/GO/PVA) composite film. The effect of nano-cellulose and graphene oxide filler on the properties of composite films was investigated.The results show that the compatibility among nano-cellulose, graphene oxide and polyvinyl alcohol is good. The tensile strength, barrier properties, water resistance and thermal stability of composite films can be improved by adding a small amount of the filler. The tensile strength of composite films with 2 wt% nano cellulose and 0.1 wt% graphene oxide are 88.48 MPa and 90.96 MPa, which improved by 24.17% and 27.66% than pure polyvinyl alcohol film, respectively. Under condition of 50% RH, the water absorption abilities of NCC/PVA, GO/PVA composite films are lower than that of pure polyvinyl alcohol film, as well as the oxygen permeability coefficient reduces gradually. When the contents of NCC and GO are 4 wt% and 0.3 wt%, the oxygen permeability coefficient of NCC/PVA、GO/PVA composite films are increased by 39.67% and 54.77% compared with that of pure polyvinyl alcohol film. NCC/GO/PVA ternary composite films were prepared through blending method with PVA, NCC, GO as raw materials. It shows that there is synergy effect of GO and NCC on the mechanical properties, barrier properties, water resistance and thermal stability of films, which is better than using single component. When the content of NCC is 2 wt%, and GO is 0.1 wt%, tensile strength of the composite film can reach 101.49 MPa, and breaking elongation is 78.28%, but too much reinforcing fillers may reduce the light transmission and breaking elongation of the films.