Montmorillonite/Cellulose Nanocrystals Mixed-modified Polylactic Acid

Biodegradable material is one of the most attractive material in the field of material science and engineering.Polylactic acid(PLA)have drawn much attention for its complete biodegradability.In order to optimize the performance and extend the application of PLA,montmorillonite(MMT)and cellulose nanocrystals(CNC)were chosen as the aditives in PLA.Firstly the MMT and CNC were modified by gemini surfactant.Then a series of films,including CNC or organophilic montmorillonite(OMMT)modified PLA,and OMMT/CNC mixed-modified PLA were prepared by solution casting method.The effects of OMMT and CNC on each properties of PLA were investigated.The result of tensile test revealed that CNC improved elongation at break of PLA and OMMT enhanced tensile strength of PLA,and CNC/OMMT mixed-modified PLA shows better properties than single-modified PLA.The results of DSC and TGA showed that the thermostability of PLA was enhanced by adding OMMT,but reduced by mixing CNC,and those two additives showed heterogeneous nucleation effect in PLA.Both OMMT and CNC enhanced the oxygen barrier of PLA.The surface morphology of the films was observed by SEM.The images showed that CNC and OMMT disperse in PLA equably,and OMMT presents sea island structure in CNC/OMMT mixed-modified PLA film.What is more,Ag/CNC was obtained by chemical reduction method,and it was used to modify PLA.The Ag/CNC/PLA composite was prepared by solution casting and the properties of antibacterial,hygroscopicity,degradability and oxygen barrier were tested.The results showed that the composite films obtained antibacterial property to escherichia coli(E.coli)and staphylococcus aureus(S.aureus).Besides,it also showed higher hygroscopicity,degradability and oxygen barrier property than unfilled PLA.