Abstract: Self-locking panels connectable in a closed polygon in which each panel has opposing connecting edges and end edges with a plurality of first locking elements (1) spaced along one connecting edge and corresponding first locking element receivers (20) spaced along the other connecting edges to connect adjacent panels to prevent their separation in first and second directions orthogonal to their line of connection. Each panel also has a first backstop (30) along one connecting edge and a first backstop receiver (40) along the other connecting edge to prevent displacement of the connecting edge of one of the adjacent connected panels in the second direction. Further, each panel has a second locking element (50) adjacent one of the connecting edges and corresponding second locking element receiver (60) adjacent the other connecting edge to connect adjacent panels to prevent their relative displacement in a direction parallel to the line of connection.

Abstract: The present invention relates to the obtention of a rigid polyurethane compound, cellular or micro-cellular, reinforced or not, having a density ranging from 0.20 to 1.30 g/cm.sup.3 ; the formation of this compound happens through the mixing of a resin composed of a mixture of polyether and polyester polyols aminated or not, having a molecular weight ranging from 100 to 5000, employed at 5 to 100 parts by weight; surfactant based on dimethylpolysiloxane, employed at 0.1 to 5 parts by weight; amine catalysts of the tetramethylethylenediamine and dimethylcyclohexylamine type employed at 0.