Study On Preparation And Properties Of Antimicrobial Poly (Lactic Acid) Materials

Appropriate antimicrobial agents were selected and added to poly lactic acid(PLA).Antimicrobial PLA/Ag films and PLA/chitosan blend films were prepared by solution approach and extrusion blend respectively,and antimicrobial effects,long-acting antimicrobial properties,mechanical properties and degradable properties were researched.The PLA materials which were prepared have antibacterial activity and remain their mechanical properties and degradable properties.The antimicrobial effects of PLA films which were respectively added 2 percents of TiO2,nano-Ag-TiO2,AM-5,nano-Ag,CAH-2 and chitosan were tested.It was found that the PLA films which were contained AM-5,nano-Ag and chitosan had antibacterial activity and nano-Ag and chitosan less affected the molecular weight of PLA films.Antimicrobial PLA/Ag films were prepared by solution approach.It was found that adding a few silver-type antimicrobial agents could make the PLA film antimicrobial,when the content of antibacterial agent was 1%or more than 1%,the antimicrobial effect on Escherichia coli,Staphylococcus aureus and Canidia Albicans of the films could achieved 100%.The film had long-acting antimicrobial property,and the silver-type antimicrobial agents didn't dissolve out from PLA film.The adding of silver-type antimicrobial agent did not affect the tensile strength and the elongation at break of the films.The films were degraded in soil environment.After 16 weeks the mass losses of films were few but the molecular weight changed a lot.The adding of antimicrobial agents did not affect the degradation of the film.PLA/chitosan blend films with different chitosan contents were prepared by extrusion blend.It was found that the antimicrobial ratio of PLA/chitosan blend films with 2 percents or more than 2 percents of chitosan could achieve more than 90%,and adding a little chitosan did not affect the mechanical properties of films.However,as a natural antibacterial agent,chitosan has poor stability,making the films of poor long-term antibiotic.The results of degradation experiments in soil and solutions showed that the adding of chitosan could speed up the decrease of the PEA films' molecular weight and tensile strength,however,the decrease of the PLA films' quality did not performance such law because of chitosan adsorption property.The pH of buffer solutions affected the degradation of the films,too.It was found that the PLA films' molecular weight and tensile strength reduced faster in the alkaline buffer solutions,but the PLA/chitosan blend films' quality reduced faster in acidic buffer solution because chitosan dissolved in acid solution.With the degradation of film,the pH of buffer solutions decreased gradually,while adding chitosan can delay the decrease of the pH.