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防凍劑
維基百科,自由的 encyclopedia
防凍劑,又稱阻凍劑、抗凍劑,是防止液體凝固或組成過大冰晶的物質。
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在汽車上使用時,防凍劑除了要防止它們在高於引擎最低工作溫度的溫度凝固,兼防止冷卻系統的金屬生鏽。1930年代前,甲醇是最流行的防凍劑,可是它的熱容量和沸點都很低,而且時間一長,它的份量會因蒸發而漸漸減少。1937年,開始使用乙二醇,其沸點高,使得它取代甲醇,直到現在仍流行。其缺點是有毒。丙二醇是沒有毒性的防凍劑,它以甘油為原料。1980年代Jack Evans發現使用無水的防凍劑——乙二醇及丙二醇的混合液,其沸點超過攝氏180度。