Structure and strength of spider silk and application to environmental by use of the degradation of its orb-web

本文的目的是：(1)研究蜘蛛丝的结构和强度；(2)探讨酸雨和紫外线（UV）环境对日本Nephila clavata （Jorougumo）蜘蛛球网变形行为的影响及其对其居民环境评价的适用性。为了研究蜘蛛拖丝和捕丝的基本特性，进行了(1)表面观察、(2)氨基酸分析、(3)红外光谱分析、(4)热分析和(5)动态力学分析等试验。在此基础上，利用自制的蜘蛛丝拉伸试验机，获得了蜘蛛丝和捕丝的应力-应变曲线，评价了蜘蛛丝的力学性能，并研究了紫外线照射和准酸雨对蜘蛛丝和球网的降解情况。结果表明：(1)蜘蛛丝主要由甘氨酸和丙氨酸中性氨基酸组成；(2)牵引绳索直径约2-4mum细纤维制成的,(3)拉铲挖土机温泉浴场稳定约250゚C,(4)牵引绳索的弹性模量和抗拉强度小约5倍,但断裂应变和能量打破大约5倍比最好的人造纤维,(5)紫外线照射诱导拉铲挖土机的退化,(6)目前没有不及格的酸雨degaradate牵引绳索,(7)捕获线的应力-应变曲线为j型，断裂应变约为200%，是曳绳的10倍；(8)重新确定了捕获线的特殊机构——卷扬机系统。

The aim of this report is (1) to investigate structure and strength of spider silk and (2) to discuss the effect of environment of acid rain and ultraviolet ray (UV) on the deformation behavior of the orb-web of the spider Nephila clavata called Jorougumo in Japan and the applicability to an environmental assessment on its inhabitant.In order to investigate the fundamental characterristics of the spider dragline silk and capture thread, some tests of (1) surface observation, (2) amino-acid analysis, (3) FTIR analysis, (4) thermal analysis and (5) dynamic mechanical analisis were performed. Furthermore, using a home-made tensile testing machine specially devised for spider thread, stress-strain curves of draglines and capture threads were obtained to estimate the mechanical properties, and the degradation of the dragline and the orb-web due to the UV irradiation and the exposure to quasi-acid rain were investigatedIt was shown that (1) the spider dragline silk consisted mainly of neutral amino-acids of glysine and alanine, (2) the dragline with diameter of about 2-4mum was made of finer fibrils, (3) the dragline was thermaly stable up to about 250ﾟC,(4) the elastic modulus and the tensile strength of the dragline were about 5 times smaller, but the fracture strain and the energy to break were about 5 times larger than those of the best man-made fiber, (5) the UV irradiation induced the degradation of the dragline, (6) the acid rain which falled at present did not degaradate the dragline, (7) the stress-strain curve of the capture thread was J-shaped and the fracture strain was about 200%, which is 10 times larger than that of the dragline and (8) a special mecanism of the capture thread named windlass system was reconfirmed.