| abstract |
Processes using high temperature thermoplastic polymers in the in-situ fabrication in the formation of foamed composite sandwich or foam articles often result in weak unsound products which may be avoided by utilizing a high temperature thermoplastic in powder form (22), a blowing agent having a high decomposition temperature (24), and, if desired, reinforcers and/or fillers (28), admixing the thermoplastic, blowing agent and reinforcer and fillers (30), placing the admixture in a mold and, if forming a composite structure, in abutment with at least one skin (34), compacting the contents of the mold (37), and applying sufficient heat and/or pressure to the mold and its contents to melt the thermoplastic and generate gas within said mixture by decomposition of the blowing agent (38). Also, an activator may be included with the blowing agent which promotes the production of gas (26). The thermoplastic should be free from any material which will react with the blowing agent or the activator at temperatures below the melting point of the thermoplastic. Articles made by the process are also disclosed. |