สำนักราชบัณฑิตยสภา

99 Jaruwan Krongsin, Roongkan Nuisin, Supaporn Noppakundilograt, Suda Kiatkamjornwong วารสารราชบัณฑิตยสถาน ปีที่ ๓๗ ฉบับที่ ๔ ต.ค.-ธ.ค. ๒๕๕๕ Stability of the leave-on conditioner by rheometry Stability of the leave-on conditioner was determined using a controlled stress rheometer (Mohlin gemini HR nano, Malvern Instruments, Malvern Worchester, England) equipped with the cone-plate size of c40/2Ti, 0.07 mm gap geometry, angle of 2 º , and shear rate of 1 s -1 . The scans were performed in triplicate cycles at temperatures from 4 to 40 º C at a constant shear stress of 1.0 Pa, and a strain frequency of 1.0 Hertz (6.2832 Radian s -1 ) in a closed system to prevent water evaporation. At the mentioned shear stress and strain frequency, a linear viscoelastic region was established. Storage and loss moduli at varying times (0 to 650 s) were obtained. A triplicate experiment was carried out. Hair characterization Cuticle scale patterns of the virgin hair and treated hair were identified based on the material analysis method of the Scientific Working Group, 2011. 11,12 The scale patterns were im- printed on a nail polish. The hair was put on a glass slide, coated with the paddy cure nail polish, and left to dryness in air. The hair was carefully lifted from the cured nail polish thin film. Hair morphology was examined using an optical microscope (model BH2, Olympus Optical Co., Ltd, Tokyo, Japan). RESULTS AND DISCUSSION The primary emulsion of menthol with the average droplet size ( d e ) of 19.6±2.3 µ m and CV of 11.5% was successfully prepared via the SPG membrane average pore size of 5.2 µ m (Figure 1). The detailed experimental data and discussion about the synthesis and characterization of the microcapsules are given elsewhere. 13 Chitosan layer of the microcapsules was crosslinked via ionic bonding between the positively charged amino groups of chitosan and the negative charge of TPP. The size of the final microcapsules was 27.6±7.2 µm with CV of 26.3%. Chitosan/menthol microcapsules emulsion was the important ingredient for a leave-on hair conditioner. It mainly composing of the chitosan/menthol microcapsules and a conditioner base was examined for the rheological behavior.