环氧树脂中的环氧当量

AN-T-136

2020-08

Reliable determination according to EN ISO 3001 and ASTM D1652 by potentiometric titration

环氧树脂中的环氧含量对树脂的反应性以及树脂固化过程中获得的涂层性能有很大影响。因此，环氧含量对于生产商和消费者来说都是一个重要的质量控制参数。该分析基于溴化氢与样品中环氧基团的反应。溴化氢则是由四乙基溴化铵（TEABr）与标准高氯酸反应生成的。EN ISO 3001 和 ASTM D1652 标准描述了用滴定法测定环氧当量重量（EEW）表示的环氧含量。使用 Titrando 自动电位滴定仪和 Solvotrode easyClean 代替手动滴定大大提高了测定的重现性和重复性。

The epoxy content of epoxy resins has a strong influence on the reactivity of the resins as well as on the properties of the coating obtained from the resin curing process. The epoxy content is thus an important quality control parameter for manufacturers as well as consumers.

The analysis of the epoxy content is based on the reaction of hydrogen bromide with the epoxy groups of the sample. Hydrogen bromide in turn is produced by the reaction of tetraethylammonium bromide (TEABr) with standardized perchloric acid.

The standards EN ISO 3001 and ASTM D1652 describe the determination of the epoxy content expressed as epoxy equivalent weight (EEW) by titration. The use of a Titrando and Solvotrode easyClean instead of manual titration greatly increases the reproducibility and repeatability of the determination.

This application is demonstrated on the epoxide-containing portion of a two-component adhesive. No sample preparation is required.

Figure 1. 905 Titrando equipped with a Solvotrode easyClean for the analysis the epoxide equivalents controlled by a 900 Touch Control.

This non-aqueous titration is performed on a 905 Titrando system equipped with a magnetic stirrer and a Solvotrode easyClean for indication.

The sample is weighed into a titration beaker, and then dissolved in either chloroform or methylene chloride. Afterwards, TEABr reaction solution and glacial acetic acid are added, and the sample is titrated with standardized perchloric acid until after the equivalence point is reached.

The analysis demonstrates acceptable and reproducible results and well-defined titration curves. For the tested two-component adhesive an epoxy equivalent weight (EEW) of 186.35 (n = 3, SD(rel) = 0.98%) is determined. An example titration curve is displayed in Figure 2.

Figure 2. Titration curve for the EEW determination of the epoxide-containing component of two-component adhesive.

The determination of the epoxide equivalent weight (EEW) in epoxy resins can be performed easily using a 905 Titrando. The use of the Solvotrode easyClean, which is suitable for non-aqueous titrations, ensures reliable determinations of the equivalence point. A flexible sleeve diaphragm facilitates its cleaning. Using the correct electrode greatly increases the precision and reliability of the results. Thus, the reliable determination of the epoxy content in epoxy resins according to EN ISO 3001 and ASTM D1652 becomes possible in a simple manner.

咨询

瑞士万通中国

北京市海淀区上地东路1号院1号楼7层702
100085 北京

咨询

Internal reference: AW TI CH1-1169-052014