Abstract: A water soluble polymer containing acid groups can be fractionated into higher and lower molecular weight fractions by partial neutralization of the polymer as a solution in a blend of water and a low molecular weight alcohol and separating the resultant aqueous and organic phases.

Abstract: Thermal energy storage compositions comprise a thermal energy storage material, for instance an inorganic hydrate that can undergo a change of hydration with accompanying release or storage of latent heat of hydration at a temperature of 10.degree. to 100.degree. C., held in a matrix of polymeric material, generally acrylic polymer. In one aspect of the invention the composition is in particulate form and so can, for instance, be poured into the heat exchanger in which it is to be used. In another aspect of the invention the storage material includes polyvalent metal ions and the polymeric material is a cationic polymer. In another aspect of the invention the composition is made by forming a solution, generally in water, of all the polymerizable material and most or all of the storage material and then polymerizing the polymerizable material in this solution. The solution is generally a low viscosity fluid and polymerization may be conducted in the heat exchanger vessel in which the composition is to be used.