Inner tubes of tires are often made of butyl rubber.
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usage
丁基 is the systematic Chinese name for the butyl group (C4H9), where 丁 is the 4th Heavenly Stem used by Chinese chemistry to number carbon chains: 甲 C1, 乙 C2, 丙 C3, 丁 C4. So 丁烷=butane, 丁基=butyl, 丁酸=butyric acid, and 丁基橡胶=butyl rubber.