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2.
Silk is a kind of natural fiber with good luster strength elasticity dyeability hygroscopicity and other advantages. Silk products are quite popular to the customers because of their excellent performance such as heat preservation air permeability and so on which make them comfortable to use. Silk floss which is made from pupa lining secondary cocoon etc. can be used as floc and filler materials and is an important part of silk products. According to its production mode silk floss can be divided into manual silk floss and machine-made silk floss and the latter has become the main processing mode of silk floss production due to its high production efficiency. In terms of composition silk flossing generally contains 20% - 30% sericin pupa oil and impurities so in the degumming process in addition to adding sodium carbonate and other degumming agents to remove sericin a large amount of hydrogen peroxide with strong oxidation property is also used to increase the cleanliness and smoothness. Unfortunately hydrogen peroxide is highly flammable and explosive and poses a risk in transportation and storage causing potential safety hazards to the silk processing industry. In order to solve this problem we innovatively propose two hydrogen peroxide-free processing methods of machine-made silk floss by using sodium percarbonate degumming or sodium carbonate-ozone. As an environmentally friendly solid oxidant sodium percarbonate can produce hydrogen peroxide and sodium carbonate after decomposition and is often used to degrade organic harmful substances. Similarly ozone is a common strong oxidant with broad-spectrum antibacterial properties and because ozone can be produced instantly by ozone generators there is no risk of transport and storage. Silk is composed of silk fibroin and sericin. Among them silk fibroin is fibrous protein which will swell in hot water while sericin is globular protein which is easy to dissolve in hot water. As a result in this paper heated sodium percarbonate solution and sodium carbonate-ozone system were used to deglue silk floss. The methods were as follows silk floss was degummed three times in boiling 0. 78 g / L sodium percarbonate solution for 30 minutes each time or was degummed three times in boiled 0. 5 g / L Na2 CO3 solution with ozone continuously flow at a rate of 100 mg / L - h for 30 minutes each time. After cleaning and drying the degummed silk floss can be obtained. After the experiment the apparent morphology sericin residual efficiency impurity rate compression resilience whiteness and other silk floss quality indexes of the two methods were analyzed and compared with superior machine-made silk floss processed by commercial way with hydrogen peroxide. The results show that both two processing methods got uniform degumming effect of silk floss and the surface of the single fiber was smooth and the degumming effect was basically the same as that of commercial products prepared with hydrogen peroxide. The sericin residual rate of silk floss was between 3% - 4% which was in line with the requirements of less than 5% of superior silk floss. There was no significant difference between silk floss obtained and commercial superior products in smoothness and whiteness. In conclusion the performance of silk floss in all aspects has reached the standard of superior products that is the sericin content is not more than 5% the impurity content is not more than 0. 1% the compression rate is not less than 45% and the response rate is not less than 92% . Based on the experimental results and analysis it can be concluded that the machine-made silk floss with good performance can be prepared without hydrogen peroxide showing the feasibility of processing machine-made silk floss without hydrogen peroxide which is of great significance to the research and development of a safe and reliable oxidant system for the removal of impurities in silk floss and to further improve the safety of machine-made silk floss production process. © 2022 China Silk Association. All rights reserved. 相似文献
3.
研究了Ti-5Al-4Zr-10Mo-3Cr合金经过β相区固溶(880 ℃)、不同温度时效(540~620 ℃)处理后次生α相(αs)析出形貌及其对力学性能的影响。结果表明:随着时效温度由540 ℃升高至620 ℃,合金中析出αs相片层厚度由0.030 μm增加到0.142 μm,屈服强度由1353 MPa降低至1074 MPa,断后伸长率由2.5%升高至11.4%,即时效析出的微米级片层αs能够显著调控合金的力学性能。此外,时效温度升高使合金的拉伸断裂由沿晶脆性断裂为主转变为韧窝穿晶为主的韧性断裂方式。Ti-5Al-4Zr-10Mo-3Cr合金时效析出的片层状αs相的厚度大于0.1 μm,合金的断后伸长率≥6%。当时效温度为600 ℃时,合金的硬度为387 HV10,抗拉强度为1182 MPa,伸长率为8.5%,具有良好的强塑性匹配。 相似文献
4.
Zhai Shengnan Yu Kejing Meng Chaoran Wang Hongbo Fu Jiajia 《Journal of Materials Science》2022,57(15):7491-7502
Journal of Materials Science - In this paper, an eco-friendly method of producing hybrid silica aerogels by freeze-drying method (FD) is proposed. In the freeze-drying system, deionized water was... 相似文献
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Mobile Networks and Applications - In order to effectively identify the pattern of personalized adaptive learning in online education and improve the recommendation satisfaction of personalized... 相似文献
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