Abstract: Composition based on a urea-formaldehyde polycondensate, suitable for the preparation of solid foams to be used as thermal insulating materials, characterized in that said composition contains hexamethylenetetramine in quantities comprised between 2% and 15% by weight with respect to the content of dry product of the composition.

Abstract: Unsaturated polyester resins having an acidity number of 5-90 mg. KOH/g. and a molecular weight of 500-5000 and which are capable of entrapping air or other inert gases so as to form structural foams and contain in the chain 0.1 to 20 mol % of amide and/or amine groups. These groups are preferably derived from the reaction of an organic compound having two reactive groups at least one of which contains nitrogen with the polycarboxylic acid and/or polyvalent alcohol contained in the polyester resin.

Abstract: Unsaturated polyester resins having an acidity number of 5-90 mg. KOH/g. a molecular weight of 500-5000 and which are capable of entrapping air or other inert gases so as to form structural foams and which contain in the chain 0.1 to 20 mol% of amide to the minimum acceptable link section size. Acceptable chain links are therefore excluded from fitting into the opening whereas worn chain links which have been worn to a degree which equals or exceeds the limit of permissible wear slide into the opening thereby indicating that the chain should be removed from service.