Lesson Five五课Silk丝绸For approximately 3000 years China successfully held the secret of silk and sericulture and held a virtual monopoly on the silk industry. About AD 300 Japan learned the secret of raising silkworms and reeling the filaments from the cocoons.约3000年，中国成功举办了丝绸和养蚕的秘密持在丝绸行业垄断。
约公元300年日本学习养蚕缫丝的丝茧的秘密。
Throughout history, silk has maintained a position of great prestige and is considered a luxury fiber. It is often called the "queen of fibers" Perhaps one of the most important contributions silk has made in the history of textiles is that it was responsible for investigation into the possible productionof man-made fibers. Scientists observed how the silkworm spun the fibers and believed that people could duplicate the art.纵观历史，丝绸一直保持着巨大的显赫地位，被认为是一个奢侈的纤维。
它通常被称为“纤维皇后”也许是最重要的贡献之一的丝绸纺织品的历史是负责为人造纤维的生产调查。
科学家们观察到，蚕纺纤维和相信人们可以复制艺术。
Silk is one of the strongest natural fibers used in creating textile products. It has a tenacity of2.4 to 5.1 grams per denier when dry. Wet strength is about 80 to 85 percent of the dry strength. Silk has good elasticity and moderate elongation, when it is dry, the elongation varies from 10 to25 percent; when wet, silk will elongate as much as 33 to 35 percent. At 2 percent elongation the fiber has a 92 percent elastic recovery.丝绸是最强的天然纤维用于制造纺织品。
它有一个坚韧的2.4到5.1克每否认干燥时。
湿强度是约80至百分之85的干强度。
蚕丝具有良好的弹性和适度的延伸，当它是干燥的，从10到25 %的伸长率的变化；当湿，丝伸长多达33到百分之35。
在百分之2伸长率下的纤维具有百分之92的弹性恢复。
Silk has medium resiliency. Creases will hang out relatively well, but not so quickly or completely as for wool.蚕丝具有介质弹性。
折痕将比较好，但不太快或完全作为羊毛。
The density of specific gravity of silk is cited as 1.25 to 1.34 grams per cubic centimeter, depending on the resource used. Because of the nature of silk, it is possible that the density varies among fibers as well as between the various types of moths that form the fiber. Another source of variation may be due to methods used in determining density. In any case, the density results in the formation of lightweight but strong filaments, yarns and fabrics.丝绸的比重密度为1.25到1.34克每立方厘米，这取决于所用的资源。
由于丝绸的性质，它是可能的，密度不同的纤维以及飞蛾，形成的各种纤维之间。
另一个来源的变化可能是由于在密度测定方法。
在任何情况下，在轻而坚固的细丝，形成纱线和织物密度的结果。
Silk has a relatively high standard moisture regain of 11 percent. At saturation the regain is 25 to 35 percent. This relatively high absorption is helpful in applying dyes and finishes to silk; however, unlike many fibers, silk also absorbs impurities such as metal salts. These contaminants tend to damage silk by weakening the fiber or causing actual ruptures to occur when the fabric is not handled properly.蚕丝具有相对高的标准回潮率百分之11。
饱和回潮率是25到百分之35。
这种相对高的吸收是在应用染料和完成对丝绸有帮助；然而，不像许多纤维，蚕丝也吸收如金属盐杂质。
这些污染物会通过削弱纤维或造成实际断裂时的织物处理不当发生丝损伤。
Silk will ignite and continue to burn when there is another source of flame. After removal from the source, it will sputter and eventually extinguish itself. It leaves a crisp, brittle ash and gives off an order like that of burning hair or feathers. It burns similarly to wool.丝绸会点燃并继续燃烧时火焰的另一个来源。
从源头上去除后，它将溅射终将消亡。
它的叶子脆，脆灰和发出像燃烧的头发或羽毛的命令。
它燃烧同样羊毛。
Like other protein fibers, silk has a lower thermal or heat conductivity than cellulosic fibers. This factor, coupled with certain methods of construction, creates fabrics that tend to be warmer than comparable fabrics of cellulosic fibers.像其他的蛋白质纤维，蚕丝具有较低的热或热传导率比纤维素纤维。
这一因素，加上一定的施工方法，创造物，往往比纤维素纤维与织物的温暖。
Silk is damaged by strong alkalies and will dissolve in heated caustic soda ( NaOH ); however, silk reacts more slowly than wool, and frequently the identity of the two fibers can be determined by the speed of solubility in NaOH. Weak alkalies such as soap and ammonia cause little or no damage to silk unless they remain in contact with the fiber for a long time.丝绸是由强大的碱受损，将溶解在加热的烧碱（NaOH）；然而，丝绸的反应比羊毛更慢，而且经常对两种纤维的身份可以用NaOH溶解速度确定。
弱碱如肥皂和氨导致很少或根本没有损坏丝绸除非他们保持很长一段时间与纤维接触。
Silk protein, like wool, can be decomposed by strong mineral acids. Medium concentrations of hydrochloric acid will dissolve silk, and moderate concentrations of other mineral acids cause fiber contraction and shrinkage, The molecular arrangement in silk permits rapid absorption of acids but tends to hold the acid molecules, so they are difficult to remove. This accounts for some of the acid damage to fibroin that does not occur to keratin. Organic acids do not damage silk and are used in some finishing processes. Some authorities maintain that thescroop of silk—a rustling or crunching sound which used to be considered a natural characteristic, is actually developed by exposure to organic acids.丝蛋白，如羊毛，可以通过强无机酸分解。