Preparation And Properties Of Selective Permeation LDPE Film Based On PVA/Diethanol Amine

Modified atmosphere packaging is an effective technology for fresh food preservation,which is widely used because of its high efficiency and non-chemical reagent treatment.The efficiency and performance of modified atmosphere packaging are closely related to CO2 and O2 permeability of packaging films.However,the traditional plastic packaging film has low selective permeation of CO2 and O2,which can not meet the MAP requirements of fruits and vegetables,especially high respiration rate fruits and vegetables.Therefore,it has great engineering value to develop a selective permeation film with high selectivity of CO2 and O2.In the research,diatomaceous earth was selected as inorganic additives to blend with LDPE resin to prepare the basement membrane flim.Glutaraldehyde was selected as the crosslinking agent,diethanolamine as amino carrier,and composited them with PVA solution to prepare the coating material.The amine carrier MAP selective permeation film was finally prepared through the spin coating method.The effects of addition amount of diatomaceous earth,diethanolamine and glutaraldehyde on the CO2 and O2 selective permeability were evaluated to study the stability of the selective permeation film,the effects of the selective permeation film on the broccoli quality was also investigated.The main research contents include:?1?The permeability coefficient,heat sealing strength,dispersion effect,tensile strength and surface tension were selected as the indexs to determine the process parameters of diatomaceous earth modified LDPE film.Viscosity change ratio of coating solution and surface energy were selected as the indexs to determine the process parameters of coating liquid.The experimental results showed that when the ratio of diatomaceous earth and LDPE resin was 3:100,the permeability of basement film was increased,the physical and barrier properties of the basement film was optimal.When the corona treatment intensity reached 80V/m2,the surface tension of basement film achieved the maximum.When the PVA adding amount was 11%,the coating liquid was the most stable,when the PSA96 adding amount was 1%,the surface energy of coating liquid was reduced to the maximum extent.?2?Diethanolamine and glutaraldehyde was mixed with the selected coating liquid,and then coated it on the basement film to prepare the high selective permeation film.The effect of the addition of diethanolamine and glutaraldehyde on the selective permeation of CO₂/O₂ were studied.The experimental results showed that when the diethanolamine adding amount was 20% the selectivity coefficient of CO₂/O₂ was 5.13.When the glutaraldehyde adding amount was 7%,the stability of the selective permeation film was the best,and the selectivity coefficient of CO₂/O₂ could also be further improved,the maximum was up to 9.23.?3?The change of weight loss rate,color,soluble solids,hardness,browning index,and vitamin C of broccoli were investigated in order to study the effects of selective permeation film on the broccoli quality.The results showed that the quality indexes of broccoli which was packaged in the selective permeation film were better than the pure natural basement film,LDPE film,and placed in natural control group,so the selective permeation film had high application value in extending the shelf life of food with high respiration rate.