Preparation And Properties Of Eucommia Gum/polylactic Acid Composite Film

At present,most of the materials used for food packaging are derived from petroleum.The petroleum-based materials aggregated are non-degradable,and the impact on the environment will be more and more obvious.In addition,petroleum is a non-renewable resource,and the increasing exhaustion of such natural resources limits the development of food packaging industry to a certain extent.Polylactic acid(PLA)is a biodegradable thermoplastic polyester,which is prepared from renewable raw materials.Therefore,it is environmentally friendly,non-toxic,fast in degradation and high temperature resistant.It has many excellent properties that petroleum-based plastics do not have,and has a very broad application prospect.Eucommia ulmoides gum(EUG)is an important biopolymer.Because of its excellent physical and chemical properties,such as good rubber and plastic dual properties,degradability,excellent processability and blending,it has been paid attention to by all walks of life.Therefore,this paper mixed EUG and PLA into a composite film,and explored the antibacterial activity of adding different antibacterial agents(organic/inorganic)on the composite film,and discussed the antibacterial performance of different antibacterial agents on the composite film under different reaction conditions.The main contents are as follows:First,pure Eucommia ulmoides gum was extracted from Eucommia ulmoides seeds(EUG).The structure of EUG was characterized by Fourier transform infrared spectroscopy(FT-IR)and nuclear magnetic resonance spectroscopy(NMR),and the results showed that it was trans polyisoprene.In addition,a quick and simple solution casting method was proposed to prepare EUG/PLA composite films,and the physical properties of the films were characterized.FT-IR analysis showed that the formation of EUG and PLA composite films was a physical blending process.In DSC thermal analysis,there are two glass transition temperature in the composite films,which are belonging to EUG and PLA,respectively,Due to the interaction between Eug and PLA,the thermal stability,crystallinity,barrier and hydrophobicity of the composite films are improved.Since both EUG and PLA are degradable,this study provides an innovative method for the preparation of degradable,strong and ductile polymer materials.The above results indicate that the developed EUG/PLA composite film has a wide application prospect in packaging field.Antimicrobial activity packaging can effectively delay food spoilage by providing a bad environment for microorganisms.By comparing the properties of the composite films of different components,the ratio of EUG/PLA was selected as 0.7/0.3(30%PLA)for subsequent experiments.The physical properties and antibacterial properties of Ti O₂NP_S composite films were investigated by loading the inorganic antibacterial agent Ti O₂NP_S into 0.7/0.3(30%PLA)composite films.With the increase of Ti O₂NP_S content,the thermal properties,crystallization properties,hydrophobic properties and mechanical properties of the composite film decreased.The results of bacteriostatic zone test showed that the composite film with Ti O₂NPS added had no obvious antibacterial effect.On this basis(30%PLA),the organic antibacterial agent thymol was added.The addition of thymol improved the thermal stability of the composite film,but reduced the crystallinity of EUG,and some other properties,such as hydrophobicity and mechanical properties,also decreased.The tensile strength and elongation at break decreased by 14%and 25%respectively.And discusses the different content of antibacterial agent and antibacterial properties of the composite film under different reaction temperature,the result was tested by bacteriostatic ring surface:not adding antibacterial composite film has no antibacterial properties,and the reaction of 55?temperature makes thymol accelerate volatile,reduce the amount of the load to the composite film,thus the composite film has no obvious antibacterial effect.The optimum reaction condition was 25?,and the antibacterial effect of the composite film was obvious.Therefore,antibacterial composite film has good biological activity and physical properties,showing its great potential as food active packaging materials.