Investigation And Design For The Nylon 11/poly(Vinyl Alcohol)/Organic Montmorillonite Films And Their Active Packaging System

Generally,active packaging systems use high-barrier packaging materials to prevent food from contacting air and cause food spoilage.On the other hand,oxygen absorbers are added to the packaging to consume residual oxygen,thereby controlling the food storage environment and extending the shelf life of food.Commonly used high-barrier packaging plastics such as polyester（PET）,polyamide 6（PA6）and polyamide 6,6（PA66）are non-renewable or non-degradable polymers,which may lead to oil shortages and environmental pollution.Polyamide11（PA11）was made from renewable castor oil.Studies had shown that when 27.5 wt%of poly（vinyl alcohol）（PVA）is blended into PA11,the oxygen permeability of the fully bio-based PA11/PVA film was reduced to～1.1 cm³·mm/m²·day·atm.The commonly used nano-sized filler montmorillonite has been proven to improve the barrier properties of plastics because it can increase the passage of gas molecules.In this paper,organic montmorillonite（OMMT）will be dispersed in the PA11/PVA mixture to prepare a film with higher barrier properties.And to form an active packaging system,this article will take iron-based deoxidizer as the main body,add sodium chloride modified iron powder（MFe）,nano activated carbon（ANC）and zeolite（Zeo）to prepare deoxidizer packet（OSCP）.The high barrier packaging film and OSCP will combined into an active packaging system to simulate the food packaging environment and verify the effect of the active packaging system.The specific work is as follows:Firstly,the modified OMMT and PVA were intercalated in water to prepare the OMMT modified PVA,and then the dried and crushed particles were melting blended with PA11,and then blown to prepare a high barrier film.Through the oxygen permeability test,it was found that when the OMMT content was 1 PHR,the oxygen permeability of the PA11_72.5PVA_27.5OMMT₁ film reached the lowest value of 0.218 cm³·mm/m²·day·atm.Through dynamic mechanical analysis and differential scanning thermal analysis,it was found that the dynamic glass transition temperature,melting temperature and crystallinity values of the blended film increased after adding OMMT.The cross-sectional morphology of the blended film was observed by scanning electron microscope and it was found that its microstructure became denser with the addition of OMMT.And the free volume test can find that when the content of OMMT reaches the optimal value,the free volume characteristic value of the blended film is reduced to the minimum.Secondly,the iron powder was modified with sodium chloride,nano activated carbon and zeolite were added to prepare a deoxidizer packet,and the best deoxidizer formula was found by exploring the influence of each content on the deoxidation rate.In order to simulate the application of deoxidizer in packaging,the food model was put in a high-barrier packaging bag,compares the peroxide value（POV）of the model food with or without OSCP,and verifies the deoxidation effect of the active packaging system.It was found that the addition of sodium chloride modified iron powder,nano-activated carbon and zeolite can enhance the deoxidizing effect of the deoxidizer.In the actual environment of simulating food packaging,the POV value of the model food has risen,but the POV value of the food model in the system with OSCP is significantly slower than the food model without OSCP.And the PA11_72.5PVA_27.5OMMT₁packaging with stronger barrier performance has the most obvious effect on slowing the increase of POV value of food.It can be seen that the PA11_72.5PVA_27.5OMMT₁ packaging bag with high oxygen barrier performance can effectively prevent oxygen from penetrating into the packaging system during storage.At the same time,the MFe⁴ANC₂Zeo₃ deoxidizer can absorb residual oxygen during food packaging and storage,so as to extend the life of food.