Preparation,Characterization And Safety Of Nano-modified Antibacterial Film For Marine Product Packaging

In order to prolong the preservation time of the marine products during the transportation and sales,it is necessary to improve antibacterial property of the packaging material.Not only the type of antibacterial agent but also the dispersion and persistence of antibacterial agent is important for packaging material.The dispersion of antibacterial agent affects the stability of the antibacterial performance,and the persistence determines the durability of the antibacterial performance.In this paper,we choose nano-titanium dioxide?TiO₂?,nano-silver?Ag?,heteropoly acid,quaternary ammonium salt and phosphonium salt as antibacterial agent.By the way of surface treatment,chemical reaction and compounding,the antibacterial performance of material have been improved.Besides,the compatibility between matrix and inorganic antibacterial agent has been greatly promoted.The detailed research and contents are listed as follows:1.TiO₂ was modified by coupling agent KH570,KH550,methyltrimethoxy silane and n-butyl titanate,and then characterized by thermal weight loss analysis?TGA?,fourier transform infrared spectroscopy?FTIR?,two-phase sedimentation test,contact angle test.The results show that the modified effect of KH570 and methyltrimethoxy silane is better than the others.After treatment,TiO2 become lipophilic and then mixed with PP.By Thermogravimetric analyzer?TGA?,scanning electron microscope?SEM?and differential scanning calorimetry?DSC?,the properties of PP composites were researched.Neat TiO₂ has obvious agglomeration phenomenon,and it is difficult to disperse uniformly in PP.However,the modified TiO_2,especially modified with n-tetrabutyl titanate and methyltrimethoxysilane,is dispersed uniformly in PP.The aggregation size of TiO₂ becomes smaller and shows better compatibility with PP.The antibacterial effect of titanium dioxide modified by different modifiers changed to some extent,in which the antibacterial rate of KH570 modified titanium dioxide to coliform and staphylococcus aureus reached 94.6%and 83.0%,respectively,its effect was obvious.2.Nano-silver was modified by dodecyl mercaptan and mixed with PP.The results show that the nano-silver after treatment can be dispersed in PP more uniformly than neat nano-silver.The introduction of 0.4%modified nano-silver can make the PP film have an excellent inhibitory effect on the coliform and staphylococcus aureus.Surprisingly,modified nano-silver could achieve 100%antibacterial rate for coliform aureus.The effect of nano-silver on the crystal behavior and thermal stability of the composite film is little,while on the dynamic modulus is more.3.Hteropolyacids,a kind of inorganic antibacterial agent,reacted with the quaternary phosphonium salts/ammonium salts which are the organic antibacterial agents to form the organic and inorganic hybrid material,then the PP composite materials were prepared by the melt blending.The antibacterial performance of the PP composite material was researched.The results show that different anions and cations have a great effect on the antibacterial performance,and the antibacterial effect of the tetraphenylphosphonium chloride and the phosphotungstic acid are better.With a loading of 8%,it can achieve 73.5%antibacterial rate for coliform aureus and 99.7%for staphylococcus aureus.Although phosphotungstate modified long-chain quaternary ammonium salt is easier to disperse,it has low antibacterial efficiency.This fact indicates that the antibacterial effect is not only closely related to the dispersion,but also by the type of the antibacterial agent.The effect of the antibacterial effect of the quaternary phosphonium salt is better than the quaternary ammonium salt.Even if compatibility of tetraphenylphosphine is slightly worse than that of long-chain alkylammonium,but its antibacterial properties are still better than those of long-chain alkylammonium.4.The nano-silver and the phosphotungstate salt were compounded,then the PP composite material was prepared by the melt blending method.The antibacterial performance was researched and showed that the nano-silver and the phosphotungstic acid in the PP film showed a very good bacteriostatic effect.With a loading of 0.05%nano-silver and 1%phosphotungstic acid,the PP film can achieve more than 99%antibacterial rate of the coliform and the staphylococcus aureus,which means good synergistic effect between nano-silver and phosphotungstic acid.5.After simulation migration experiments,it is found that nano-silver migrates differently in water,acid,alcohol and oil food simulants,and the migration trend is 4%acetic acid>n-hexane>20%ethanol>water,and its trend increases with the increase of contact time and temperature.Furthermore,considering the special effects of nanoparticles,the animal toxicology and cytotoxicity tests of nanosilver were carried out,and the acute,subacute and cytotoxicity of nanosilver was studied.The results show that the nano-silver has low toxicity and no skin sensitization.The results of human breast cancer cell toxicology experiments show that the effect of nano-silver on cell activity gradually increased with the increase of concentration.when the concentration reached 200?g/mL,the activity of human breast cancer cells is less than 40%,which indicates that nanosilver has cytotoxicity.6.Based on the simulation of migration experiments and biotoxicology of nano-silver particles,the safety risk assessment of nano-silver composite antibacterial film exposure was carried out.The evaluation results show that there is a certain risk in the use of nano-silver packaging products,and there is a possibility of adverse reactions in long-term use.In summary,it is considered that the antimicrobial effect of nano-silver modified antimicrobial film is relatively good,and the PP composite antimicrobial film prepared by blending with phosphotungstate has also obtained excellent antimicrobial effect,and greatly reduced the amount of nano-silver added.The migration and toxicological tests of nano-silver show that there are certain risks in the long-term consumption of nano-silver composite antimicrobial material,and it is suggested to set a specific migration limit of nano-silver.