Plastics have made inroads into automobiles for a host of reasons, including lower costs, weight reduction, parts consolidation, styling, corrosion resistance and safety. Now, automakers around the world are employing plastics to reduce the noise and vibrations that used to be common feature in car interiors. Their actions reflect the demands of today's consumers, who insist on a pleasant, comfortable driving environment.
Sound reduction systems encompass the three main areas of automobiles: the passenger compartment, under the hood, and the underbody. Numerous polymers are finding roles in sound damping, including polyurethanes, polyamides, polyethylene, polypropylene, thermoplastic elastomers, and various engineering plastics. While insulation with highly sound absorbent polymers is the most common noise reduction strategy of car manufacturers, another approach is to replace metal gears with less noisy plastic ones. Sometimes these plastic parts are loaded with friction-reducing additives that lessen both sound and wear.