久久精品久久精品久久精品 I 色在线视频观看 I 亚洲黄色天堂 I 夜夜爱夜夜做夜夜爽 I 国产精品入口网站7777 I 免费一级黄色 I 综合伊人久久在 I 国产成网站18禁止久久影院 I 久久精品免视看国产成人明星 I 日本黄色软件 I 亚洲精品久久在线 I 精品少妇一区二区三区四区五区 I 国产黄视频在线 I 九九九免费观看视频 I 91插插插插插 I 在线国产二区 I 91国产片 I 国产一区二区三区视频在线 I 亚洲精品中文字幕无码蜜桃 I 精品亚洲精品 I 国产久艹视频 I 国产三级大全 I 精品久久久久国产免费第一页 I a级毛片,黄,免费观看 m I 欧美伦理片免费 I 国产精品狼人久久久久影院 I 日本又白又嫩水又多毛片 I 无码人妻精品中文字幕免费东京热 I 98久久久 I 1314全毛片 I 99亚州精品一区区三区 I 女人av天天堂 I 日本高清久久天堂 I 国产精品天干天干在观线 I ass极品水嫩小美女ass

Silicone rubber refers to a rubber whose main chain is composed of silicon and oxygen atoms alternately, and two organic groups are usually connected to the silicon atom. Ordinary silicone rubber is mainly composed of silicone chains containing methyl groups and a small amount of vinyl groups. The introduction of phenyl can improve the high and low temperature resistance of silicone rubber, and the introduction of trifluoropropyl and cyano groups can improve the temperature and oil resistance of silicone rubber. Silicone rubber has good low temperature resistance, and can still work at -55 ℃. After introducing phenyl, it can reach -73 ° C. The heat resistance of silicone rubber is also very outstanding. It can work for a long time at 180 ℃, and it can withstand elasticity for several weeks or longer when it is slightly higher than 200 ℃. It can withstand high temperatures above 300 ℃ in an instant. Silicone rubber has good air permeability, and the oxygen transmission rate is the highest among synthetic polymers. In addition, silicone rubber has the outstanding characteristics of being physiologically inert and not causing coagulation, so it is widely used in the medical field.