Preparation And Application Of Corn Cross-linked Starch/straw Fiber Composite Membrane

Due to energy shortage and increasingly serious environmental pollution problems,research on green,safe,biodegradable packaging materials has become the current more and more popular topic,development and utilization of crops and their byproduct of preparing green,environmental protection packaging materials scientists around the world to become the research hot spot,at the same time is a natural polymer future research and development direction in the field of environmentally friendly materials,and agricultural by-products in order to reduce environmental pollution and one of the effective ways to alleviate energy shortage.On the other hand,compared with foreign our country circulating and fresh-keeping of the fruits and vegetables in postharvest utilization rate is low.At present,most fresh-keeping packaging for coating,effect of fresh-keeping research less.So this thesis with cross-linking corn starch and straw fiber as main raw materials,adding to plasticizer,strengthening agent and cross-linking agent preparation has a better performance of composite membrane materials,and use it to the packaging for fruits and vegetables,in order to provide theoretical support for future research on fresh-keeping packaging.(1)Cross-linked corn starch/straw fiber composite membrane preparation and process parametersThis topic using single factor experiment method,by measuring the tensile strength of the composite membrane,elongation at break,air permeability,moisture permeability,microstructure,choose the best level of raw materials and additives has a better performance of composite membrane preparation.The experimental results are as follows:Select 2.0%,2.5%,3.0%,3.5%,3.0%(m/v)of corn cross-linked starch;2.0%,2.5%,3.0%,3.5%,3.0%(m/v)of PVA and CMC as the composite strengthening agent(mass ratio of PVA:CMC=1:2);0.5%,0.75%,1.0%,1.25%,1.0%(m/v)of rice straw fiber;2.0%,2.5%,3.0%,3.5%,3.0%(v/v)glycerol as strengthening agent;1.0%,1.5%,2.0%,2.5%and 3.0%of glycerol as the cross-linking agent preparation of composite membrane,through experiments it is concluded that:when the corn cross-linked starch content is 3.0%(m/v),straw fiber content is 1.0%(m/v),composite strengthening agent content is 3.0%(m/v),glycerol content is 3.0%(v/v),glycerol addition amount of 2.0%(v/v)composite membrane when the optimal performance,Test indicators:the tensile strength of 22.26 MPa,elongation at break was 24.64%,Amount of265.21(g·m²)^-1·24 h,CO₂ coefficient of 5.63×10^-16 m²·s^-1·Pa^-1.Use buried soil degradation on the degradation of composite membrane were tested,the experimental results show that:composite membrane of weightlessness rate above 50%when50 d,So it have better performance of degradation.(2)The application of composite film packagingThe strawberry and mulberries as the experimental material,design the control group(LDPE cling film)and blank group,by measuring the weightlessness rate of strawberries and mulberries,decay rate,total soluble solids and total number of colonies,indicators to compare effect of modified atmosphere packaging composite membrane.Through experiments it is concluded that:under the condition of 4?,decay rate,soluble solids content and total number of colonies,effect of modified atmosphere packaging composite film is better than LDPE film,composite film packaging of strawberries and mulberries began to rot when 7 d,and LDPE cling film packaging strawberries and mulberry were widespread decay to nearly 6 d,and the box with sour odor;At 20?and 30?,strawberry and mulberry at its 3 d and 2 d begun to rot,but the preservation effect is better than LDPE film composite membrane.So the composite film had a certain degree of preservation effect.