Abstract: A single-use self-heating container has an insulating external envelope. A plastic vessel is within and attached to the envelope. A membrane separates the vessel into an upper compartment which contains one reagent and a lower compartment which contains another reagent. A membrane-breaking member is in the lower compartment. A metallic container with a thermally welded peelable cover is fastened to an upper portion of the plastic vessel. To prevent abrupt temperature changes, the upper compartment of the plastic vessel may contain a temperature control substance which undergoes a change in state between 90.degree. and 100.degree. C.

Abstract: Process for the preparation of polyaldehydes by polymerization with a redox system, of bifunctional monomers having the general formula: ##EQU1## wherein R.sub.1 = R.sub.2 = H and R.sub.3 is --H, --CH.sub.3, --C.sub.2 H.sub.5, --C.sub.3 H.sub.7, --C.sub.6 H.sub.13, or --C.sub.6 H.sub.5 or R.sub.1 = R.sub.3 = H and R.sub.2 is --CH.sub.3, --C.sub.6 H.sub.5, or --CH.sub.3 --CH = CH, performing the polymerization under stirring, in absence of light and in an oxygen free nitrogen atmosphere, for a period of 2-20 hours, at a temperature ranging from 0.degree. to 40.degree.C, using degassed and double distilled water as a solvent and K.sub.2 S.sub.2 O.sub.8 /AgNO.sub.3 as a redox system, adding degassed and double distilled water to the polymerized mass, collecting the polyaldehyde by filtration and centrifugation, washing several times with water, then with 0.1 N HNO.sub.3, again washing with water and finally with acetone and drying the product.