engleski

Changes in polymer foils used in food packaging using DSC

This work is an experimental study of DSC characterisation of polymer materials used in food packaging materials such as Polypropylene (0.03 mm), polyethylene (0.1 & 0.03 mm), poly(D-(-)-b-hydroxybutyrate) (powder), two-layered polypropylene (0.064 mm), and two-layered polypropylene with poly(vinilyden chloride) (0.012/0.021). The polymer stability was checked by simulation of condition during food preparation in microwave oven, sterilisation or rapid freezing. The materials were tested in the temperature range from 40 to 200°C at different scan rates from 2°C min-1 to 30°C min-1during heating or cooling. The enthalpies show a high correlation coefficient (0.964) with scan rate. All samples undergo phase change in the temperature range from 107 to 173°C during heating and enthalpies were in the range from 31.8 to 71.1 J g-1. Upon subsequent cooling from 200°C, the temperature range of phase changes was shifted to lower temperatures from 86 to 102°C with enthalpies ranged from 30.4 to 57.8 J g-1. Experiments with exposure of polymers to microwave radiation and freezing proved that the phase change considering the temperature range is very similar in all experiments.

DSC; polymers; food packaging; enthalpy; phase change

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