Degradation And Migration Of Irgafos 168 And Its Degradation Products From Nanocopper/Polypropylene Composite Films

Polypropylene(PP),known as the common-used food contact material,plays an important role in food packaging filed by preventing food products from deterioration and damage.To improve its performance and extend the shelf life,additives usually were added in to PP materials.Irgafos 168(tris(2,4-di-tert-butylphenyl)phosphite),as one of the common antioxidants,is widely used in polyolefin industry to protect polymer from aging and oxidation.During polymer processing,however,Irgafos 168 may degrade into several degradation products among which 2,4-di-tert-butylphenol(DP1),and tris(2,4-di-tert-butylphenyl)phosphate(DP2)were the major two degradation products which belong to NIAS that may have toxicity and higher migration potential.Therefore,it is necessary to focus on the degradation and migration factors of Irgafos 168 in food contact materials.Based on this situation,this paper mainly focus on factors during the whole food supply chain from raw material production to food manufacture,packing,retail,wholesale,consumer use including sunlight exposure and high temperature during storage and logistics,ultraviolet as sterilization method,microwave heating for consumer using and different oxygen concentration in modified atmosphere packaging.Detailed studies are as follows:(1)Different PP composite films were manufactured by extruding PP-R matrix with Irgafos 168,Irgafos 168 and nanocopper,Irgafos 168 and KH550 modified nanocooper,PP-B and PP-H matrix with Irgafos 168 and nanocopper,respectively,using twin-screw extrusion machine and film-blowing machine.(2)The thickness,color and mechanism properties of PP composite films were detected.For color of composite films,significant chromatism were found which was due to the addition of Irgafos 168 and nanocopper,whereas no significant effects of PP structural on chromatism were found.For mechanism properties,the addition of nanocopper significantly promoted the elongation at break(EAB)of composite films,however,no obvious effects on tensile strength(TS)of each composite films were found.Besides,the improved addition amount of nanocopper and the addition of KH550 have no significant effect on TS and EAB of each composite films.For different PP structural composite films,nanocopper/PP-H obtained the lowest EAB compared to other two films.Nanocopper/PP-B obtianed the highest TS than nanocopper/PP-R and nanocopper/PP-H composite films.(3)Different factors during the whole food supply chain from raw material production to food manufacture,packing,retail,wholesale,consumer use including sunlight exposure and high temperature during storage and logistics,ultraviolet as sterilization method,microwave heating for consumer using and different oxygen concentration in modified atmosphere packaging,were all investigated in this work.The films were treated by UV irradiation,microwave heating,sunlight exposure,placed in different oxygen concentration conditions,suffered the extrusion process and high temperature,respectively.UV irradiation significantly accelerated the degradation of Irgafos 168 compared to other treatments,DP1 in nanocopper/PP-R films increased to maximum value at 24 h and decreased afterwards.However,the amount of DP1 in nanocopper/PP-B and nanocopper/PP-H increased to about 8 times of initial concentration and then reached to a balance.The introduction of nanocopper notably promoted DP1 generation after extrusion whereas suppressed DP2 generation which also caused a higher degradation rate of Irgafos 168 and sharp decrease of DP1 under microwave heating,sunlight exposure and high temperature treatment.No significant difference between the effects of nanocopper and KH550 modified nanocopper on degradation of Irgafos 168 was found.(4)Migration test of Irgafos 168,DP1 and DP2 were conducted at different temperature(20?,40?and 70?)after the film treated by 30 min UV irradiation and 100 d sunlight exposure.The influence of nanocopper,KH550 and three PP structural on migration of Irgafos 168,DP1 and DP2 were all investigated.The results of migration after UV irradiation showed that the addition of nanocopper inhibited the migration of Irgafos 168 and DP2 but promoted the migration of DP1.The migration of Irgafos 168,DP1 and DP2 in three different PP structural films were still in the order of PP-R > PP-B > PP-H which means the addition of nanocopper has no effect on the migration order in three different PP structural films.The results of migration after sunlight exposure showed that the addition of nanocopper inhibited the migration of Irgafos 168 and had no significant effect on DP2 migration.There was no significant effect of the addition of KH550 on the migration of the Irgafos 168 and its degradation products.(5)AKTS-SML software was used to simulate the migration of Irgafos 168 and its degradation products from PP-R and PP-H composite films into food simulant,and the simulation results and experimental results were compared.The results showed that the simulated migration of each substance in PP-R composite membrane was higher than that of PP-H;The simulated migration of Irgafos 168 was higher than the experimental results;the results of DP1 experiment after UV treatment were significantly higher than that of the simulation results,however the DP1 experimental results were similar to the simulation results of the sunlight migration test;the DP2 experimental results of each test were similar to the simulation results.