Shrinkage alkali effect

Alkali treatment reduces shrinkage temperature (Fysh, 1958), and Courts (1960) suggests a minimum figure of approximately 44°C for limed ossein (demineralized bone). At this stage few intermolecular cross-links can be present because the material can be dissolved in water at 60°C. Gustavson (1962) has shown that treatment with periodate also lowers the shrinkage temperature (Ts) by as much as 20°C. This could suggest that alkali and periodate attack the same cross-link, but other side reactions under the conditions used will also have some effect. 

Cotton filter cloths are among the most widely used filter media. They have a limited tendency to swell in liquids and are used for the separation of neutral suspensions at temperatures up to 100°C, as well as suspensions containing acids up to 3% or alkalies with concentrations up to 10% at 15-20°C. Hydrochloric acid at 90-100°C destroys cotton fabric in about 1 hour, even at concentrations as low as 1.5%. Nitric acid has the same effect at concentrations of 2.5%, and sulfuric acid at 5%. Phosphoric acid (70%) destroys the cloth in about six days. Water and water solutions of aluminum sulfate cause cotton fabrics to undergo shrinkage. 

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