engleski

Thermal stability of nano and micro composites of LDPE used in food packaging

Polymer packaging materials play an important role in the food manufacturing process. It makes food more convenient and gives the food greater safety assurance from microorganisms and biological and chemical changes such that the packed foods can have longer shelf life. In order to meet the huge demand of processed food with longer shelf life, various new packaging materials have been studied. Low density polyethylene (LDPE) is the most commonly used polymer for packaging with its advantages of being inert, permeable to gases and impermeable to water vapor. Thus, suitable for packaging should have desired levels of selective permeability to oxygen, carbon dioxide and nitrogen gases which necessitates commodity diffusion resistance and their effects on quality parameters to be established together with the effect of temperature. The permeability may be improved by adding reinforcing compounds like zeolite and/or nano-clays forming composites. Gas diffusion across a film is determined by film structure, thickness, area, concentrations gradient across the film, temperature, and differences in pressure across the film. In this study samples of polyethylene containing zeolite, T-MAZ 7 and nano-clays, Cloisite 20A were extruded and further examined on the thermal stability by thermogravimetric analysis (TGA). The influence of the characteristics of the inorganic particles on the thermal properties of the composite is tested using the isoconversional Kissinger Akahira Sunose method. For these purpose the experimental data were measured at different heating rate (5, 10, 15 and 20°/min). The results show that the obtained values of the activation energy of the thermal decomposition for the nano and micro composites are changed with varying inorganic content.

packaging material; low density polyethylene; thermal stability; thermal properties

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