Abstract: A process for preparing structural, heat-insulating shaped bodies which does not necessarily require the use of a foamed heat-insulating material obtained by the use of blowing agents belonging to the class of chlorofluorocarbons. The process includes inserting a heat-insulating pre-molded core inside a tubular element made from an extruded thermoplastic polymer; placing the extruded tubular element containing the pre-molded core into a blow-molding mold; and molding the tubular element into a shell by blow-molding. By subsequent mold closure, the shell adheres to the pre-molded core. An alternative process is disclosed for adhering the tubular element and pre-formed core by closing the mold and drawing a vacuum within the tubular element.

Abstract: Process for preparing heat-insulating structural elements, which comprises the steps of:(a) applying to the convex portion of a first half-shell a layer of beads made from a semi-foamed or foamed thermoplastic polymer, in order to produce a layer with an essentially constant thickness;(b) sintering the beads; and(c) applying to the so obtained composite a second half-shell capable of fitting the shape of the sintered layer.

Abstract: Selective thermodegradation of homo- and copolymers of propylene, without encountering thermo-oxidation phenomena, by treating the polymer at 250.degree.-350.degree. C. in the presence of primary and/or secondary antioxidant and of a derivative of benzopinacol having formula (I): ##STR1## wherein n=1, or=0, and when n=1, X may be=1, and in this case Z.sub.1 and Z.sub.2 form together with each other ##STR2## groups, ##STR3## wherein R.sub.1, R.sub.2, R.sub.3, which may be the same or different, are alkyl or aryl radicals;or X ranges from 3 to 20 and in this case Z.sub.1 and Z.sub.2 are aryl radicals, A and B are R.sub.1 -Si-R.sub.2 groups that are part of an oligomer having formula: ##STR4## and when n=0, X is=1, Z.sub.1 and Z.sub.