Aplicações

Os poliuretanos são um dos tipos de plástico mais comumente usados. Eles são produzidos pela reação de polióis brutos com isocianatos. Dependendo do material de partida pode ser obtida uma grande variedade de plásticos. A determinação do índice de acidez, do índice de hidroxila e do teor de isocianato desempenha um papel importante na análise de matérias-primas para plásticos. O índice ácido da matéria-prima poliol é geralmente usado no controle de qualidade para garantir a uniformidade entre lotes. Além disso, é usado como fator de correção para calcular o verdadeiro número de hidroxila. Neste Boletim de Aplicação é descrita a determinação do índice de acidez de acordo com ASTM D4662 e ASTM D7253. Uma matéria-prima para poliuretanos são os polióis. Os polióis contêm vários grupos hidroxila. Portanto, o número de hidroxila de uma matéria-prima se correlaciona diretamente com a quantidade de polióis presentes e é, portanto, um importante parâmetro de controle de qualidade. Neste Boletim de Aplicação é descrita a determinação do índice de hidroxila de acordo com ASTM E1899 e DIN 53240-3. Como os polióis reagem estequiometricamente com os isocianatos, o conhecimento do teor de isocianato é um importante parâmetro de qualidade para a produção de poliuretanos. Neste documento é descrita a determinação de acordo com EN ISO 14896 método A, ASTM D5155 método A e ASTM D2572.

Polyols are important raw materials in polyurethane production. Contamination in the raw materials have a great influence on reactions and impair the quality of the end product. Alkali metals are particularly strong catalysts for linear or branched reactions. A rapid and precise method for their simultaneous determination is ion chromatography following Inline Matrix Elimination.

1,3,5-trioxane is a heterocyclic compound formed by trimerization of formaldehyde. Trioxane is used for the production of polyformaldehyde plastics such as poly(oxymethylene) (POM) and solid fuels. Aqueous 1,3,5-trioxane solutions frequently contain trace triethylamine that requires quantification. This is performed on the Metrosep C 3 - 250/4.0 column with subsequent direct conductivity detection.

The water content of melamine is determined according to Karl Fischer in a buffered solvent mixture at 50 °C.

The water content of beta-caprolactam is determined according to Karl Fischer.

The water content of vinyl chloride is determined according to Karl Fischer.

Toxic and corrosive chemicals such as p-toluenesulfonyl isocyanate (TSI) and tetrabutylammonium hydroxide are used for the Hydroxyl Number analysis of polyols by titration according to ASTM D4274-16. This application note demonstrates how the XDS RapidLiquid Analyzer operating in the visible and near-infrared spectral region (Vis-NIR) provides a cost-efficient and fast solution for the determination of the hydroxyl (OH) number of polyols. With no sample preparation or chemicals needed, Vis-NIR spectroscopy allows for the analysis of polyols in less than a minute.

This Application Note describes the determination of multiple quality parameters (hydroxyl number, acid number, and moisture content) of polyols using Vis-NIRS. Without any sample preparation, this unique analytical technique enables straightforward quantitative analysis.

Caprolactam is an important polymer used for the production of Nylon 6, which is the base material for industrial fibers. Due to its commercial significance, many different synthesis methods have been developed over the years. Caprolactam is hygroscopic and water soluble, therefore it is important to have a reliable analysis technique for water determination. Analyzing the water content by conventional methods requires each sample to be weighed, dissolved, heated, and titrated. Compared to the primary method, near-infrared spectroscopy (NIRS) offers unique advantages: it generates reliable results within seconds, but it does not need any sample preparation nor does it create chemical waste.

Permanganate absorption number (PAN) analysis per ISO 8660 ensures caprolactam purity, a precursor of Nylon 6. This application describes real-time, continuous PAN monitoring.