Preparation And Research Of The Gelatin Mineral Composite Strengthening Films

In this paper,we use gelatin as the main film forming material.Then added laponite and Nano-hydroxyapatite(nHA)respectively to prepare two kinds of gelatin-mineral composite films.The aim of this research is to study the properties of the mineral composite films.Gelatin-laponite composite films were mainly prepared with gelatin,laponite,calcium lactate and glycerol.Through a single factor experiments to get the optimum concentration range of the film components.And then carry on the orthogonal experiment(L934).Thickness,tensile strength,elongation at break,water vapor permeability,water-soluble,the light transmittance was measured.Through the comprehensive performances evaluation,the best film components formula was achieved:gelatin concentration of 7%,laponite 15:1(compared with gelatin),calcium lactate concentration of 3%,glycerol concentration of 45%.Under this condition,the performance of the composite membrane is better.We use infrared spectroscopy to analysis the interaction of the composite component of the films.The results of Fourier transform infrared spectroscopy(FTIR)indicated that the gelatin molecules and laponite have a strong interaction.The surface and cross section morphology of the composite films were observed and analyzed by scanning electron microscopy.The results showed that with the addition of laponite the films's surfaces became rough.It shows that there is a certain relationship connected with the films' mechanical properties and water vapor permeability.The cross section of the composite films with laponite is more homogeneous than the films without laponite.It shows a better compatibility with gelatin.Gelatin-Nano hydroxyapatite composite films were mainly prepared with gelatin,Nano hydroxyapatite(nHA)and glycerol.It was found that the properties of the composite films with Nano-hydroxyapatite were improved.The mechanical properties of the composite films with 10%concentration of Nano hydroxyapatite were better than the others.The tensile strength and elongation at break were 43.25%and 37.25MPa respectively.When Nano-hydroxyapatite added concentration of 20%,the water vapor permeability is as low as 0.126 g·mm/KPa·h·m,the lowest oxygen permeability is 22.10 Meq/Kg.The addition of Nano hydroxyapatite can significantly increase the color difference of the composite films and increase the transparency value.The maximum value of the two indicators is 7.203 ±0.519 and 3.606 A/mm respectively.The thermodynamic properties of Nano hydroxyapatite composite membranes were analyzed by differential scanning calorimetry(DSC),and the thermal stability of the composite films was improved by the addition of Nano hydroxyapatite.The crystallization of Nano hydroxyapatite in the composite films was analyzed by X diffraction.Through scanning electron microscopy(SEM),atomic force microscopy(AFM),the surface and cross section morphology of the.composite films were observed and analyzed.The results showed that the surface of the composite films was rough and the structure was uniform.The infrared spectra of the composite films with different concentrations of Nano hydroxyapatite were analyzed,and the relationship between the formation and the mechanism of the film formation was analyzed.The results showed that there was a chemical binding between gelatin and Nano hydroxyapatite.Adding minerals in gelatin can improve the properties of gelatin films,so it will be a new possibility in the future to apply it to the research and production of food packaging.