| abstract |
A layer of thermoplastic sheet material such as sheet ABS is heated to a temperature at which it is thermally formable and while at this temperature is thermally formed, as by differential gas forming, typically vacuum forming, against a shaped body of cellular thermoplastic material such as expanded polystyrene. As a result of the heat in the sheet as it is drawn against the cellular body which is at room temperature, fusion welding of the sheet to the surface of the cellular body at the interface takes place. No cement or other adhesive, organic solvent or the like is used. The result is that the cellular body is protected against puncturing, shattering under impact, abrasion, and other physical influences that would normally tend to injure it and is made much stronger. The disadvantages of prior attempts to make such composites, such as the need for preforming the sheet and then bonding it to the body and the need to use solvent-based cements or organic solvents, are completely obviated. The invention is exemplified by the manufacture of a boat having an expanded polystyrene core and layers of sheet ABS covering and fusion welded to its interior and exterior surfaces. |