Abstract: A process for obtaining cellular materials from unsaturated polyester resins reinforced with fillers having a density below 0.7 kg/lt by injecting a liquid foam, made from the resins by mechanical introduction of a gas therein into a closed mold, is described. The liquid foam, obtained from polyester resins including additives and optionally a reinforcement of synthetic, artificial, vegetable or mineral fibres having a length lower than 5 mm, and optionally containing a low boiling foaming agent, is injected voluminized and cross-linked in the hot or in the cold in a closed mold containing a reinforcing agent of synthetic, artificial, vegetable or mineral fibers as a monofilament mat, a cut fibre mat, a mono or bidirectional roving woven mat, rovings, fabrics.

Abstract: A process for the preparation of high concentration solutions of cellulose erivatives in organic solvents comprises contacting with paraformaldehyde and the solvent a cellulose which has a polymerization degree lower than 300 and preferably not significantly higher than 200. The solvent is selected from among dimethylformamide, dimethylacetamide and N-methylpyrrolidone.

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.