Study On Preparation And Properties Of Vermiculite Modified Polyvinyl Alcohol Film

As a water-soluble and environmentally friendly plastic packaging material,polyvinyl alcohol(PVA)film has become one of the research hotspots in the field of green packaging.In order to obtain a PVA film with better performance,we used 1799 PVA,EVA emulsion and glycerin to be blended in water-bath heating with mechanical stirring,and then to cast into film based on the previous researches.We test the mechanical properties of PVA film prepared by casting different PVA solution concentrations and different glycerin contents,and select the film with outstanding performance.According to the solution concentration of the selected film,we used Fluko to cut and intercalate the pre-treated vermiculite sheet with the PVA solution.The mechanical properties(tensile properties,puncture properties),scanning electron microscopy,thermodynamic properties,X-ray diffraction analysis and infrared spectrum analysis of the PVA modified films with different contents of vermiculite were performed to study the effect of vermiculite on the properties of PVA film.Experimental results show:(1)When the content of glycerin at the same percentage,as the PVA percentage increased,the viscosity of the solution was increased,the thickness of the film was incrassated,the tensile strength magnified,and the Young's modulus was enhanced.When the concentration of the solution is constant,as the content of glycerin increased,the viscosity of the PVA solution decreases,the thickness of the film after casting was thinned,and the tensile strength was also reduced,but the softness of the film increases,the Young's modulus was decreased,and the elongation at break was increases.When the glycerin content is 1.2%,the 8% PVA film possess a thickness of 20 ± 1 ?m,the tensile strength reaches 46.0 MPa,and the elongation at break is as high as 108%.(2)When the PVA content is 8%,as the glycerin content increases,the glass transition temperature decreases,the crystallinity also decreases,and the thermal stability can be improved.Compared with pure PVA,when the glycerin content is 1.5%,the glass transition temperature of the PVA film is lowered by 11.1 ?,the crystallinity is reduced by 12.91%,and the mass loss rate at 300 ? is decreased by 32.66%.(3)When the vermiculite is sufficiently stripped in the PVA solution and dispersed uniformly,the glass transition temperature and the melting temperature of the PVA film are significantly improved.The glass transition temperature of the PVA film containing 0.2% vermiculite was increased by 3.6 ? and the melting temperature was increased by 2.5 ?.The addition of vermiculite also reduced the crystallinity.The crystallinity of the film sample having a vermiculite content of 0.3% was 17.78%,which was 4.52% lower than the PVA without addition of vermiculite.The better the stripping and dispersing effect of vermiculite is,the higher the mechanical property of the film is.The sample film with 0.2% vermiculite content has the highest tensile strength,and the tensile strength is increased by 2.6 MPa and the tensile modulus is increased by 9 MPa compared with the PVA film without vermiculite.After 10 minutes of heat treatment,the tensile strength of the film was increased by 80% to 130%.