Study On The Properties Of Chitosan Nanofibers And Montmorillonite Enhanced EVOH Film

Ethylene-vinyl alcohol copolymer(EVOH)is a kind of thermoplastic polymer with excellent barrier properties,which is widely used in packaging field.However,the presence of a large number of hydroxyl groups in EVOH molecules makes it more sensitive to water molecules,particularly,the oxygen barrier and physical properties of EVOH films have been reduced a lot in high humidity environments(more than 50%RH).In this paper,the comprehensive properties of EVOH films were enhanced by using nano-fiber membranes and montmorillonite nanosheets,and their structure-activity relationships were studied emphatically.Two different ways of introducing montmorillonite were used in experiments;one was filling montmorillonite loaded chitosan-poly(ethylene oxide)nanofibers with polyethylene-vinyl alcohol copolymer(EVOH),the other was filling CPF with the blends of EVOH and MMT,then the two composite films of EVOH-MMT@CPF and EVOH-MMT-CPF were obtained respectively.The structures were characterized to study their thermal stability,mechanical properties,barrier properties and antibacterial properties.The construction of MMT@CPF was achieved by the electrostatic self-assembly between MMT and CPF.The experimental results showed that the thermal stability and mechanical properties of the EVOH film matrix were significantly improved after filling MMT@CPF and MMT30-CPF,which possessed excellent oxygen barrier properties EVOH-MMT@CPF(0.2×10-16 cm3 cm cm-2 s-1 Pa-1),EVOH-MMT30-CPF(0.21 ×10-6 cm3 cm cm-2 s-1 Pa-1)and good water vapor barrier EVOH-MMT@CPF(4.6×10-6 g m m-2 s-1 atm-1,relative humidity 90%)?EVOH-MMT30-CPF(5×10-6 g m m-2 s-1 atm-1,relative humidity 90%).This significant increase in barrier properties is attributed to its tortuous pathway that delays the penetration of molecules.Therefore,the composite membranes may have a great potential in food packaging.