Lemon essential oil desorption from polypropylene/talc nanocomposite films

Abstract

A phenomenological analysis on desorption mechanism of lemon essential oil in semicrystalline polymer nanocomposites is performed. Films made with polypropylene and talc nanoparticles obtained by blown extrusion are used as a case study due to the high complexity of sorption phenomena in such systems containing a semicrystalline polymer and nucleating particles. In this sense, a systematic analysis combining both morphological effects and intrinsic properties of each component is considered. Talc characteristics as its morphology, surface chemistry, oil absorption properties, particle size mean and distribution, and impurities presence are considered in desorption analysis. Regarding semicrystalline matrix, morphological and crystalline changes induced by talc nanoparticles and processing are included in this study. Desorption of lemon essential oil from nanocomposite films with different talc concentrations (0, 1 and 5 wt%), which have distinctive and well characterized morphologies, is evaluated through gravimetric and thermogravimetric analysis. Results show that polypropylene film has a desorption rate higher than nanocomposites containing 5 wt% and lower than those with 1 wt%. This behavior is a consequence of the global crystallinity configuration changes produced by nanoparticle concentration and film obtaining process. It is revealed that simplified and conventional approaches that consider tortuosity as unique effect of particle presence in nanocomposites mass transport do not allow to comprehend the desorption mechanism involved in a complex system such as the semicrystalline polymer nanocomposites. The present study gives additional insight into the complex mechanism involved in desorption of strongly swelling oil in nanocomposite films based on semicrystalline polymers and nucleating mineral particles.