This paper summarizes a study of controlled migration of an antifog (AF) additive; sorbitan monooleate (SMO), from linear low density polyethylene (LLDPE) films containing a compatibilizer, LLDPE grafted maleic anhydride (LLDPE-g-MA). LLDPE/LLDPE-g-MA/SMO blends were prepared by melt compounding. Bulk and surface properties of compression molded LLDPE films containing SMO and LLDPE-g-MA were characterized using Fourier transform infrared spectroscopy and contact angle measurements. Thermal properties were investigated using a thermal gravimetric analyzer. Diffusion coefficient (D) was calculated, and AF properties were characterized using a "hot fog" test. Compression molded films were characterized for their morphology using high-resolution scanning electron microscopy, and rheological properties were measured using a parallel-plate rotational rheometer. It was found that the LLDPE/LLDPE-g-MA/SMO systems are characterized by a slower SMO migration rate, a lower diffusion coefficient, and lower contact angle values compared with LLDPE/SMO blends. These results are well correlated with results of a hot fog test. Morphological studies revealed a very fine dispersion of SMO in the LLDPE films, when 3 phr LLDPE-g-MA was combined with 1 phr SMO. Thermal analysis results show that the incorporation of 3 phr LLDPE-g-MA and 1 phr SMO significantly increases the decomposition temperature of the blend at T > 400°C. At high shear rates, the LLDPE blends show that the AF and the compatibilizer have a lubrication effect on LLDPE.

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Essential oils (EOs) are volatile natural organic compounds, which possess pesticidal properties. However, they are vulnerable to heat and light, limiting their range of applications. Encapsulation of EOs is a useful approach to overcome some of these limitations. In this study, a novel emulsification technique is utilized for encapsulation of thymol (TY) and eugenol (EU) (EOs) within microcapsules with an unmodified cellulose shell. Use of low cost materials and processes can be beneficial in agricultural applications. In the encapsulation process, unmodified cellulose was dissolved in 7% aqueous NaOH at low temperature, regenerated to form a dispersion of cellulose hydrogels, which was rigorously mixed with the EOs by mechanical mixing followed by high-pressure homogenization (HPH). Cellulose:EO ratios of 1:1 and 1:8 utilizing homogenization pressures of 5000, 10,000 and 20,000 psi applied in a microfluidizer were studied. Light microscopy, high-resolution cryogenic scanning electron microscopy (cryo-SEM) and Fourier transform infrared spectroscopy (FTIR) revealed successful fabrication of EO-loaded capsules in size range of 1 to ~8 µm. Stability analyses showed highly stabilized oil in water (O/W) emulsions with instability index close to 0. The emulsions exhibited anti-mold activity in post-harvest alfalfa plants, with potency affected by the cellulose:EO ratio as well as the EO type; TY showed the highest anti-mold activity. Taken together, this study showed potential for anti-fungal activity of cellulose-encapsulated EOs in post-harvest hay.

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