Relation between the particle size and release characteristics of aromatic melamine microcapsules in functional textile applications

Abstract

The relation between the particle size and release characteristics of aromatic microcapsules with a melamine resin shell in functional textile applications have been investigated. Firstly, the microcapsules are characterized based on their Fourier transform infrared spectra, encapsulation efficiencies, particle size distributions, optical images, and scanning electron microscopy images. The impregnation performances of the microcapsules have been initially evaluated using image analysis. Subsequently, the impregnation efficiency and broken release characteristics are semi-quantitatively analyzed using solid-phase microextraction-gas chromatography-mass spectrometry. The analysis results show that the highest impregnation efficiency and broken release intensity could be observed when the microcapsule size was similar to the fiber diameter (25-30 μm). Eventually, the sustained release of the microcapsules over a period of 2400 h was evaluated using the weighing calculation method, and the trends were studied using the Peppas model. It was found that the microcapsule release rate slowly and continuously decreased with time, and the release rates significantly increased with the decrease in microcapsule particle size. Thus, it could be concluded that the large microcapsules exhibited better leak tightness than the small microcapsules, whereas the small microcapsules exhibited faster sustained release rates.

Fig. 1. Schematic diagram of the sustained release behavior test.

Fig. 2. The Fourier transform infrared spectra of the (a) essence oil, (b) microcapsules, and (c) MMF resin.

Fig. 3. SEM images denoting the morphology of the prepared microcapsules: (a) as-prepared microcapsule and (b) broken microcapsule.

Fig. 4. OM images denoting the morphologies of prepared microcapsules having different particle sizes (a₁–e₁) and the corresponding fabric samples finished by microcapsules (a₂–e₂).

Fig. 5. SPME-GC-MS elution curve of the fabrics treated using microcapsule sample 1.

Fig. 6. (I) Mass spectra of 1,8-eucalyptol in the core material and (II) SPME-GC-MS elution curves of the fabrics treated by (a) sample 1, (b) sample 2, (c) sample 3, (d) sample 4, and (e) sample 5.

Fig. 7. Relation between the peak height of the SPME-GC-MS characteristic peak and the average microcapsule particle size.

Fig. 8. The sustained release data and fitting curves for microcapsules having different particle sizes.

Fig. 9. Predicted sustained release characteristics of microcapsules having different particle sizes.