聚氯乙烯Polyvinyl chloride

工业 PVC 主要是无规立构，结晶度只有约 5–10%，玻璃化温度约 80 °C。C–Cl 键的极性使其分子间作用力强、硬度高，并具有自熄性（含氯高，阻燃）。PVC 热稳定性差，在约 100 °C 以上开始脱 HCl，生成共轭多烯而变色，因此加工时必须加入热稳定剂（铅盐、钙锌、有机锡）。加入 30–50% 邻苯二甲酸酯等增塑剂可把 Tg 降到室温以下。

Commercial PVC is mostly atactic with only about 5–10% crystallinity and a glass transition near 80 °C. Polar C–Cl bonds give strong interchain forces, rigidity and self-extinguishing behaviour thanks to the high chlorine content. PVC is thermally unstable: above about 100 °C it begins to lose HCl, forming coloured conjugated polyenes, so heat stabilisers (lead salts, calcium–zinc, organotins) are required. Adding 30–50% plasticisers such as phthalates lowers Tg below room temperature.

1835 年勒尼奥首次制得氯乙烯，1872 年鲍曼发现氯乙烯在阳光下变成白色固体。1912 年克拉特获得氯乙烯合成和聚合专利，但当时无法加工。1926 年美国古德里奇公司的西蒙发现加入增塑剂可使 PVC 柔软易加工，开启了工业化。1974 年发现氯乙烯单体导致工人患肝血管肉瘤，此后对残留单体有了严格限制。

Regnault first made vinyl chloride in 1835, and Baumann found in 1872 that it turns into a white solid in sunlight. Klatte patented vinyl chloride synthesis and polymerisation in 1912, but the polymer could not then be processed. In 1926 Waldo Semon at B.F. Goodrich found that plasticisers make PVC soft and processable, launching the industry. After vinyl chloride monomer was linked in 1974 to liver angiosarcoma in workers, residual monomer was strictly limited.

硬质 PVC 用于给排水管、门窗型材、地板和信用卡；软质 PVC 用于电线绝缘层、人造革、输血袋和医用导管。焚烧 PVC 会产生 HCl 并可能生成二噁英；部分邻苯二甲酸酯增塑剂有内分泌干扰作用，儿童玩具中已被限制。氯乙烯主要由乙烯氧氯化法或电石乙炔法生产。

Rigid PVC goes into water and drain pipes, window profiles, flooring and credit cards; flexible PVC into cable insulation, artificial leather, blood bags and medical tubing. Burning PVC releases HCl and can form dioxins, and some phthalate plasticisers are endocrine disruptors and are restricted in toys. Vinyl chloride is made mainly by oxychlorination of ethylene or from carbide acetylene.