4. Conclusions
Morphology of LDPE-EVA blended films mixed in twin-screw extruder showed that the two compositions in blended films are discrete and immiscible. Moreover, the SEM micrographs showed better distribution of EVA phase in matrix when the composition of EVA was no more than 10%wt. From the DSC results, it confirmed that the two-polymer blended film were immiscible. The study of morphology of the films incorporated with EOs reveals rough and grainy surface because of discontinuous phase of polymer and evaporation of EOs. Residual concentration of EOs showed that different Eos could demonstrate different rate of volatilization. Solubility parameter is the main factor to be taken into consideration in term of residual concentration after processing. For the CB, its residual concentration is even noticeable due to its polarity different to the polymer backbone. In term of antimicrobial activity testing, the film incorporated with CB showed the best performance of inhibiting the growth of E. coli and S. aureus regardless of its low retention. Nonetheless, the relatively higher retention of EOs in the film with SB is incapable of resisting both microorganisms. Lastly, the modification of film with any EOs illustrated a well-maintained condition for tomatoes comparing to the ones packed in the film with no EOs even a long period of two months. Consequently, LDPE-EVA films incorporated with such EOs are practically suitable to use for food and agricultural product packaging.