A new process could make nanocomposites feasible for parts such as body panels, according to Ford Motor Co. (www.ford.com). The technology uses sound waves to increase the compatibility between microscopic reinforcement materials and plastic resin used to make nanocomposite parts.
Mixing solid microscopic particles of smectite clay with plastic resin creates the so-called nanocomposites. Automotive manufacturers prefer the tiny clay particles over larger talc, mica, or glass-fiber fillers, which often leave part surfaces bumpy and cause parts to crack more easily in the cold. Nanocomposites are stronger and lighter than other plastic composites and may replace steel, aluminum, and conventional plastics in body-panel applications.
But, developing nanocomposites has been mired by the clay's lackluster interaction with automotive plastics such as polypropylene and polyethylene. Ford scientists found that bombarding clay particles with sound vibrations during mixing causes the filler to better disperse throughout the design matrix, improving a part's strength without using costly agents. "The method disperses clay particles as single platelets throughout the matrix," says Ford scientist Ellen Lee.
For example, GM's Saturn Corp. has used plastic door panels for years. But, to let the material expand and contract, larger than normal gaps are placed between doors and body side panels. Nanocomposite parts are cheaper and lighter, with better impact characteristics and lower coefficients of liner and thermal expansion. According to Lee, using nanocomposite parts will allow manufacturers to get around things like big gaps for clearances between doors. Mass production of nanocomposite parts using this technology is several years away.