Meaning
Specialized chemical mixtures prevent interference during moisture analysis of polymers containing reactive functional groups. Keto-reagent formulations are modified Karl Fischer solutions that replace methanol with alternative solvents like formamide or 2-methoxyethanol. This substitution is necessary because methanol reacts with ketones and aldehydes to form acetals or ketals, a process that releases water as a byproduct.
Using standard reagents on resins that contain these groups would result in a false high moisture reading that never stabilizes.
Side Reaction
Chemical interference occurs when the solvent in the titration cell interacts with the chemistry of the sample. By employing keto-reagent formulations, a chemist avoids the formation of water from the condensation reaction between alcohols and carbonyl groups.
Material Applicability
Selection of the correct chemical system is necessary for specific polymers like certain polyesters or modified resins with high additive packages. In the context of keto-reagent formulations, the lack of methanol also slows down other potential side reactions that could occur at the high temperatures used in oven-based moisture analysis. These mixtures provide a stable environment for analyzing complex formulations that would otherwise be impossible to quantify.
Accuracy Requirement
Precision in moisture detection allows a moulder to adjust dryer settings with confidence before starting a run. Because keto-reagent formulations eliminate the phantom moisture created by side reactions, they provide the true value needed to prevent part defects like splay or bubbles. This accuracy is a requirement for high precision automotive or medical components.
