Effect of chlorine dioxide gas on physical,thermal, mechanical,and barrier properties of polymeric packaging materials

The effects of gaseous chlorine dioxide (ClO₂) on properties and performance of 10 selected polymeric packaging materials, including polyethylene (PE), biaxially oriented poly(propylene), polystyrene, poly(vinyl chloride), poly(ethylene terephthalate) (PET), poly(lactic acid), nylon, and a multilayer structure of ethylene vinyl acetate (EVA)/ethylene vinyl alcohol (EVOH), were evaluated. Physical, mechanical, barrier, and color properties as well as infrared (IR) spectra were assessed before and after polymer samples were exposed to 3600 ppmV ClO₂ gas at 23°C for 24, 168, and 336 h. The IR spectra of the ClO₂‐treated samples revealed many changes in their chemical characteristics, such as the formation of polar groups in the polyolefin, changes in functional groups, main chain scission degradation, and possible chlorination of several materials. The ClO₂‐treated PE samples showed a decrease in tensile properties compared with the untreated (control) films. Decreases in moisture, oxygen, and/or carbon dioxide barrier properties were observed in the treated PE, PET, and multilayer EVA/EVOH/EVA samples. A significant increase (P < 0.05) in the barrier to O₂ was observed in the ClO₂‐treated nylon, possibly the result of molecular reordering, which was found through an increase in the crystallinity of the material. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mass transfer study of chlorine dioxide gas through polymeric packaging materials

The mass transfer profile (permeability, diffusion, and solubility coefficients) of chlorine dioxide (ClO₂), a strong oxidizing agent that is used in food and pharmaceutical packaging, was determined through various common polymeric packaging materials. A continuous system for measuring permeation of ClO₂, using an electrochemical detector, was developed. It was observed that biaxially‐oriented poly(propylene), poly(ethylene terephthalate), poly(lactic acid), nylon, and a multilayer structure of ethylene vinyl acetate and ethylene vinyl alcohol were better barriers for gaseous ClO₂, as compared to polyethylene, poly(vinyl chloride), and polystyrene. The activation energies of permeation for ClO₂ through poly(ethylene terephthalate) and poly(lactic acid) were determined to be 51.05 ± 4.35 and 129.03 ± 2.82 kJ/mol, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, , 2009     

Antimicrobial efficacy of gaseous chlorine dioxide against Salmonella enterica Typhimurium on grape tomato (Lycopersicon esculentum)

The aim of this study was to investigate the effects of gas level and treatment condition on antimicrobial efficacy of ClO₂ gas against Salmonella enterica Typhimurium on grape tomato (Lycopersicon esculentum). Grape tomatoes were dip‐inoculated with inoculum of S. enterica Typhimurium TISTR 292 (ATCC 13311) (9.79 ± 0.39 log CFU mL^?1) and allowed to dry before treatments. The pre‐inoculated samples were exposed to 0.15–0.85 mg of ClO₂ gas, for up to 58 min. The treatments at 4 and 25 °C resulted in population reductions of S. enterica Typhimurium of up to 3.95 ± 0.22 and 7.37 ± 0.39 log CFU per fruit, respectively. The population reduction results were used to construct statistical models to predict efficacy of ClO₂ gas. The second‐order equations for treatments at 4 and 25 °C had R² of 0.87 and 0.95, respectively, and indicated that efficacy of ClO₂ gas was significantly influenced by ClO₂ gas level, exposure time and treatment temperature.