Dissipation of an organophosphorus pesticide, trichlorfon, in natural and waxed apples during storage was studied. The results showed that the trichlorfon content in natural and waxed apples decreased by 85% and 64%, respectively, during storage. The morphology of the surface film was dense and regular, which resulted in a higher water vapor resistance and a lower respiration rate in the waxed apples. This indicates that waxing affected the dissipation of pesticide residues in the apple storage environment, increasing food safety risk. Ozone was used to remove the residual pesticides on the apple surface. The trichlorfon degradation rate reached 73%. The ozone treatment had no effect on the surface color of the apple, which means that the fruit can be pre-treated with ozone prior to waxing or storage.
The beeswax used in Chinese traditional hot waxing is expensive and has relatively scarce resources. To provide a low-cost alternative and expand the applications of hot waxing for wood repair and protection, polyethylene wax grafted with maleic anhydride and methyl methacrylate was used for the hot waxing treatment of wood. The surface/interface between wax and wood was characterized by Fourier-transform infrared spectra (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD), and the effects of hot waxing temperature and time on the surface roughness and gloss, hydrophobicity, adhesion and thermal stability of treated wood were studied. The properties were compared with those of wood hot waxed with beeswax. The results showed that the modified polyethylene wax filled the wood cell lumina, cross-linked with the wood matrix, and formed a smooth and continuous wax layer on the wood surface. This greatly reduced the wood surface roughness and improved surface gloss. The hydrophobicity and thermal stability of wood were also improved, and the wax layer adhered well to the wood. When used to hot wax wood samples at 180 ℃ for 40 min, the wood modified with polyethylene wax achieved superior gloss, adhesion, and thermal stability to the wood treated with beeswax.
We presented a facile method for preparing a food-safe superhydrophobic packaging paper with improved moisture and air barrier properties in this study, which is combining construction of polymer-nanoclay hybrid multilayers with subsequent carnauba wax treatment. The polymer-nanoclay hybrid multilayers consisting of quadlayers of carrageenan (CR)/chitosan (CS)/montmorillonite (MMT)/CS were created using layer-by-layer (LbL) assembly. The surface chemical compositions, potentials and morphologies of the CR/CS/MMT/CS multilayer-modified paper samples were investigated. The paper sample modified with a wax-treated (CR/CS/MMT/CS) 2 multilayer gave a water contact angle of 151.4°. Compared with original paper, this superhydrophobic paper sample showed comparable tensile strength and excellent barrier properties against water vapor and air. Moreover, the obtained paper was used for strawberries packaging at ambient temperature, and it was very effective at reducing the weight loss and maintaining titratable acidity compared with the unpackaged strawberries, which might has a great potential as food packaging materials.
To prevent the degradation of wood surfaces by ultraviolet radiation and liquid water, modified polyethylene wax and modified polyethylene wax/oxidized paraffin composite wax were used for the protection of wood surfaces with hot wax treatment. The effects of natural beeswax coating and modified synthetic wax coating on wood surface aging behavior were also studied. Results showed that changes in color, gloss, water uptake, contact angle, micro-morphology, and chemical changes of wood treated with modified synthetic wax hot waxing were less than those of wood treated with natural beeswax hot waxing after long-term aging under ultraviolet (UV) light and water. Among them, the modified polyethylene wax/oxidized paraffin composite wax coating showed the best protective effects on the wood surface, and the composite wax coating reduced the UV penetration and enhanced the UV oxidative degradation resistance. In addition, the synergistic effect of modified polyethylene wax and oxidized paraffin further reduced the water uptake of wood during aging process. This data clearly shows that the modified synthetic wax and composite wax coating can effectively inhibit the photooxidative degradation of wood surface, provide a lasting hydrophobic protection effect on wood, and show long-term photostability.
危险品化学品经营许可证（带存储）