橡胶中羟基含量

Determination of carboxyl groups (-COOH) containing plastics or rubber is based on acid/base titration by dissolving the sample in titration solvent and then titrating with methanolic potassium hydroxide solution. If the samples are not dissolved at room temperature, heating is necessary. -COOH + KOH 􀃆 -COOK + H2O Appropriate titration solvent shall be selected according to the property of each sample. There is a method to detect the end point with a pH electrode, however rubber or plastic samples may be very sticky and may adhere to the electrode resulting in abnormal potential reading in many cases, so normally the end point is detected by color indicator titration. In this report, chloroform is used as titration solvent and phenolphthalein is for indicator.