Preparation And Application Of The Peppermint Oil Microcapsules

Most of the essential oils such as peppermint oil are easy to volatilize because of their lowboiling points, as a resutl the essential oils can hardly bear the processing temperature whenincorporating them into fibers to manfacture fragrant fabric. Moreover, the fragrant duration willbe short because of the quick evaporation of essential oil. As a matter of fact, this problem couldbe overcome partly by using the technique of microcapsulation. Enwrapping essential oil withsuitable wall materials can not only protect it from the relatively high processing temperature, butalso restrict its evaporation to achieve the slow-release effect.In this paper, the peppermint oil microcapsules with slow-release effect were prepared bycomplex coacervation method, using gelatin and arabic gum as the wall materials and pepepermintoil as the core material. And then the obtained peppermint oil microcapsules were incorporatedinto nylon6fiber and cotton fabric respebtively by means of blend melt spinning and paddingfinish. The properties of fibers and cotton fabric were studied. The main content of this paper is asfollow：The peppermint oil microcapsules were prepared using complex coacervation method. Theprocess parameters, such as the concentration of emulsifier, the dosage of cross linker, the stirringspeed, the concentration of wall materials, the ratio between core and wall materials and the pHvalue of coacervation, were analyzed in detail. By digital polarizing microscope, laser particle sizeanalyzer, UV-Vis spectrophotometer, infrared spectroscopy, thermal gravimetric analysis andscanning electron microscopy, the morphology and the property of microcapsules werecharacterized. The optimal process parameters were the emulsifier concentration of0.5％, thecross linker dosage of6mL, the stirring speed of600rpm, the wall materials concentration of1.5％, the ratio between core and wall materials of1:2and the pH value of3.3. The oil content ofmicrocapsules prepared at optimal process was39％. Microcapsules was observed using scanningelectron microscopy, the surface was smooth with integrated structure. Laser particle sizeinstrument showed the mean particle size was about6μm. According to the experimental results,after heating at40℃for30h, peppermint oil volatilization rate was more than80％, when thepeppermint oil microcapsules volatilization rate was only20％. It showed that microcapsulationcould obviously reduce the volatilization rate of peppermint oil, promising a fairly goodslow-release property.Microcapsules prepared with the best parameters were used into melt spinning, thespinnability of fibers, mechanical properties, morphology were studied. The optimal processparameters were as follow：content of microcapsules was of0.5wt％, rheological modulators wasof5wt％, and the screw temperature was of250℃、265℃、238℃respectively. It has been foundthat the spinnability of nylon6would be reduced with the increasing microcapsule content, The mechanical properties of the fiber were also found be suppressed because of the addition ofmicrocapsules, Although the peppermint oil content in the fiber was not so high, the blend fiberpossessed an obvious fragrant effect and the fragrant release rate was slow.Microcapsules prepared with the best parameters were finished on cotton fabric throughpadding, oil content, mechanical properties, stiffness, wrinkle recovery angle, whiteness,morphology were studied. The optimum conditions were list as follow：the pre-drying temperaturewas70℃and the time was3min, the curing temperature was120℃and the time was2min. Theexistence of microcapsules could observed in both the fabric surface and the fiber gap almostwithout wall damage. The cotton fabric presented a pleasant fragrant effet and releasedpeppermint oil slowly.