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«“√ “√ √“™∫— ≥±‘ µ¬ ∂“π Usa Sangwatanaroj, et al. 135 ªï ∑’Ë ÛÚ ©∫— ∫∑’Ë Ò ¡.§.-¡’ .§. Úıı and modulus showed the opposite results. Mulberry silk had lower moisture regain but higher density and dye uptake than the non- mulberry silk which contained microvoids at the filament cross- section. However, the non- mulberry silk had a higher molecu- lar weight than the mulberry varieties. In this study, we attempted to determine the properties of three local silk filaments reeled by hand and by machine. In addition, an imported Chinese silk filament was also studied. All silk filaments were subjected to various tests to determine their characteristics and their chemical and physical properties. This scientific informa- tion is very important for various applications in textile industry. Experimental Materials The three mulberry silk filaments used in this research were two varieties of mixed hybrids between the Thai race and Japanese or Chinese race known as Chul 4 and Chul 6, and one variety of a mixed hybrid between the Japanese and Chinese races known as Chul 1. These raw filaments were reeled from silk cocoons (bivoltine) by hand and by machine at Chul Thai-Agro Industries, Thailand and only inner layer silk filaments were used. For the hand reeling, each silk variety was reeled in water at 90 º C at a speed of 19 m/min, while a Nissan automatic silk reeling machine was used for machine reeling at a speed of 90 m/min and a temperature and pH of water of 30-32 º C and 6.5-7, respectively. In addition, an imported Chinese silk filament was provided by Jim Thompson Thai Silk, Thailand. It was reeled by machine and an inner layer filament was obtained All chemicals used in this research were of reagent grade and utilized without further purification. Methods Degumming Raw silk filaments were degummed at Chul Thai Silk Co., Ltd. using 2-3 g/dm 3 sodium carbonate and 5-6 g/dm 3 nonionic wetting agent at a liquor-to-silk ratio of 30:1, at a temperature of 98 º C, pH 10 for 45 minutes in a degumming bath. Both raw and degummed silk filaments were assessed for their appearance, physical and chemical properties, according to the test methods shown as follows. Characterization Appearance, Cross-Sectional and Longitudinal Views Silk filaments were observed visually for their general appea- rance such as color shade luster, smoothness, and cleanliness in a standard lighting cabinet VeriVide under a light source of daylight (D65). They were also observed for their cross-sectional and longi- tudinal morphology under a scan- ning electron microscope (SEM, model JEOL JSM-5410LV). a fast segmental motion of the fibrous protein at a high molecular weight of 300,000. Nakamura et al. 2 investigated the thermal properties of the silk proteins in silkworms and found that water evaporated off as the temperature of the amorphous random-coil fibroin of Bombyx mori was raised to 100 º C. Intra- and intermolecular hydrogen bonds of the silk proteins were broken at the temperatures of 150-180 º C and the glass transi- tion temperature was 175 º C. Silk sericin showed a glass transition temperature of 170 º C. The glass transition temperature of wild silk fibroins varied with the species of silkworm and ranged from 160- 210 º C. Annadurai et al., 3 computed the crystal imperfection parameters and the shape of crystallites of varieties of silks (Chinese, Indian, and Japanese races) using the X-ray profile analysis, and observed the influence of these parameters on physical properties of the silk filaments. They found that silk filament having a higher crystal size value showed a higher tensile strength and percentage elongation at breaking point than other silk filaments. Sen and Babu 4-6 studied the properties of the Indian mulberry and non- mulberry silk varieties. They found that denier, moisture regain, dye uptake, and elongation of the cocoon’s outer layer filament were higher than those of the cocoon’s inner layer filament for all silk varieties while density, tenacity