| Polylactic acid is a bio-based degradable material that is based on renewable environmental resources.Polylactic acid has good biodegradability,biosolubility,good mechanical properties and easy processing.The development and use of polylactic acid materials can not only solve environmental pollution problems,but also open up a new path for the petroleum-based plastics industry。Chitosan is called chitosan,which is produced by deacetylation of chitin,which is widely found in nature.The properties of chitosan are high molecular substances,which have been widely recognized by all walks of life in society,and are also widely used in medical,food,and sewage treatment.Chitosan is not toxic,does not cause pollution,and has excellent degradability.It is mainly used in the preservation of fruits and vegetables.In the current high barrier packaging range,such as food packaging and pharmaceutical packaging,SiOx film is coated on the surface of general packaging materials to enhance barrier properties and mechanical properties.The coated SiOx film has the advantages of corrosion resistance,friction resistance,heatability,good barrier properties,and good transparency.It has been of great interest to many manufacturers and research institutions that produce thin films.In this paper,SiOx was deposited on the polylactic acid film by vapor deposition(PECVD)to form a polylactic acid/SiOx composite film.Based on this,a polylactic acid/SiOx/chitosan composite film was prepared by casting method.The hydrophilicity,mechanical properties,barrier properties,bacteriostatic properties,light transmission properties of the composite membrane were characterized,and the microscopic morphology of the surface and section of the membrane was observed by scanning electron microscopy(SEM).It is found through experiments that SiOx coating improves the hydrophilicity of the composite membrane,SiOx coating and chitosan solution improve the mechanical properties of the composite membrane,SiOx coating improves the barrier properties of the composite membrane,and the chitosan solution imparts antibacterial effect to the composite membrane.Performance,chitosan solution reduces the light transmittance of the composite film and increases the haze value.In the peeling test,the deposition of SiOx on the PLA film and the application of the chitosan solution can increase the maximum force required for peeling and enhance the peel strength of the film.In the coating thickness measurement experiment,the thickness of the chitosan coating on the surface of the polylactic acid/SiOx composite film is between 0.5 and 1.5 um,and it can be seen that the coating effect of chitosan is very good.Antibacterial experiments showed that the polylactic acid/SiOx/chitosan composite membrane had very good antibacterial properties,Chitosan imparts antibacterial properties to the polylactic acid original film.In the degradability experiment,it was found that with time,temperature and ultraviolet light reduced the tensile strength and elongation at break of PLA original film,PLA/SiOx composite film and PLA/SiOx/CS composite film due to temperature.Or ultraviolet light irradiation causes many small cracks to form inside the film,which leads to degradation of the film,and the higher the temperature,the more serious the degradation of the film.At the same time,the degradation of the film caused by temperature and UV irradiation will weaken the antibacterial property of the PLA/SiOx/CS composite film. |
