Preparation And Properties Of Fully Degradable Antibacterial Starch Film

Food is rich in a variety of nutrients and flavor substances,however,it is extremely vulnerable to external factors such as microorganisms,moisture,and oxygen during the process of storage,transportation,and marketing.Microorganisms are the most important factor leading to food spoilage and deterioration of nutritional value.Thus,the application of antibacterial food packaging film is of great significance for food preservation and quality.In this study,using ?-polylysine hydrochloride(?-PL)as the antibacterial agent,two types of modified montmorillonite were prepared by a solution method.The effects of different addition amounts of ?-PL and ultrasonic treatment with different power on the structure and properties of the modified Mt were studied.Starch was used as a film-forming substrate,and one type of modified Mt was selected to serve as the antibacterial agent.The main research contents and results are as follows(1)The effects of different addition amounts of ?-PL on the structures and properties of?-polylysine hydrochloride modified montmorillonite(PL-Mt)were investigated.PL-Mt was prepared by adding ?-PL,which accounted for 10%,30%,50%,and 70%of the mass of Mt,respectively.XRD studies showed that the d-value of PL-Mt increased first and then decreased with the increase of the addition amounts of ?-PL.When the addition amount of?-PL was 30%,the d-value of PL-Mt reached the maximum,which was 1.79 nm.The average particle size and distribution of ?-PL solution demonstrated that the average particle size gradually increased and the particle size distribution became increasingly narrower as the concentration increased,which led to the d-values of PL-Mt50 and PL-Mt70 gradually decreased.The FTIR and TGA results of PL-Mt proved that the addition amount of 30%?-PL was the most suitable(based on Mt mass)for intercalating the Mt.The antibacterial activity test of PL-Mt30 proved that 1.0 g of PL-Mt30 had a good inhibitory effect on both E.coli and B.subtilis(2)The effects of different ultrasonic powers on the structures and properties of?-polylysine hydrochloride modified organic montmorillonite(PL-OMt)were studied.The result of the XRD of OMt displayed that ultrasonic treatment facilitated Dioctadecyl dimethyl ammonium chloride(D1821)to intercalate into the Mt interlayer space.The d-value of organic modified montmorillonite(OMt)increased with increase of ultrasonic power,the minimum was OW-OMt,which was 3.00 nm.And the maximum was 1800W-OMt,which reached 3.20 nm.TGA results displayed that the mass loss of OMt increased with the increase of ultrasonic power,and the maximum was 1800W-OMt.The maximum d-value was 600W-PL-OMt,which reached 3.83 nm.However,TGA result of PL-OMt displayed that the mass loss of PL-OMt prepared with ultrasonic treatment did not change obviously,indicated 600 W was the most suitable for preparing PL-OMt.Compared with the rest of PL-OMt,the antibacterial activity test of PL-OMt also demonstrated that 600W-PL-OMt had the best inhibitory effect on E.coli and B.subtilis when the same amount was added(3)The effects of different addition amounts of PL-Mt30 on the structures and properties of PL-Mt30/starch composite films were studied.XRD result displayed that the reflection peaks of PL-Mt30 became broader and its intensity became smaller than raw PL-Mt30,indicated that PL-Mt30 was exfoliated or nearly exfoliated after itwas compounded with starch.The tensile strength(TS)of the starch composite film increased with the increase of addition amounts of PL-Mt30,the maximum was 15%PL-Mt30/starch composite film,which reached 9.62 MPa.The WVP of starch composite film decreased first and then increased,the minimum was 12%PL-Mt30/starch composite film,which was 1.7×10-12 g·cm-1.s-1·Pa-1.The antibacterial activity test result demonstrated that the 12%PL-Mt30/starch composite film had the maximum antibacterial rate,which could reach 74.29%.