Since the surfaces of polypropylene food service tableware (hereinafter called PP tableware) are easily abraded, adherence of allergen residues is a concern. In this study, we clarified the reasons for abrasion and analyzed egg allergen residues on PP tableware.
The abrasions were straight-lined, superficial (about 0.1 μm deep, and 20-35 μm wide), and similar in width to the diameter of unwoven fabric fibers. Compared to the hardness of other tableware, PP tableware was assumed to be easily abraded by unwoven fabric fibers, and the actual abrasions of the polypropylene could be demonstrated by rubbing PP tableware with unwoven fabric. This result suggested that abrasion of the PP tableware surface was due to the scouring action of the unwoven cloth used for dishwashing.
Dishwashing with a soft sponge was important to reduce abrasions, and also effective to remove egg allergen residues on PP tableware, regardless of the extent of abrasions.
Silk fabric was dyed using the extract from red and brown onion skins, and the properties of the dyed fabrics were investigated. The main natural colorant present in the red onion skin was identified as malvidin-3-arabinoside of the anthocyanins. The red onion skin contained yellow colorants, as did the brown onion skin. The colors of the fabrics dyed with and without six types of mordants, including Mg2＋, Ca2＋, Al3＋, Ti4＋, Fe3＋ and Cu2＋, were measured and expressed according to the CIELAB color system and ΔE* value. The fabrics were dyed pink without mordant and dyed green with Al3＋ and Cu2＋ mordants using the red onion. An investigation by FE-SEM, EDS, XRD and TG-DTA revealed that the dyeing did not affect the structure of the fabrics. Color fastness to light and to washing of the dyed fabrics was enhanced by treatment with Al3＋, Ti4＋, Fe3＋ and Cu2＋ mordants.
As a topic in home economics, investigations of the characteristics of wool fibers are important. In this study, the factors that affect the felting of wool were examined.
An evaluation of felting was carried out using the Aachen felt ball method. It was found that the diameter of the felt balls produced in the test decreased with increasing surfactant concentration, and was smallest at the critical micelle concentration. When wool was treated with a 0.3％ sodium dodecyl sulfate solution, its diameter was reduced by about 20％. In the pH range from 3.0 to 11.5, no significant influence of pH was observed. With a mechanical force of amplitude 3 mm, the diameter of the felt ball was reduced with an increase in amplitude. For an amplitude speed of 2,000 rpm, the diameter of the felt ball was about 20％ lower than that for an amplitude at 500 rpm. Increasing the temperature was also effective in reducing the felt ball diameter; the diameter at 50℃ was about 10％ less than that at 10℃. No significant influence of humidity was observed in the presence of sodium dodecyl sulfate.
Thus, the most important factors influencing felting were the surfactant concentration, mechanical force and temperature. In consideration of teaching materials, for the experimental setup used in the present study, the optimal conditions were found to be a 0.3％ sodium dodecyl sulfate solution, a temperature of 40℃, and an amplitude speed of 1,500 rpm.
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