Automotive industry exterior parts

Polycarbonate—polyester blends were introduced in 1980, and have steadily increased sales to a volume of about 70,000 t. This blend, which is used on exterior parts for the automotive industry, accounting for 85% of the volume, combines the toughness and impact strength of polycarbonate with the crystallinity and inherent solvent resistance of PBT, PET, and other polyesters. Although not quite miscible, polycarbonate and PBT form a fine-grained blend, which upon analysis shows the glass-transition temperature of the polycarbonate and the melting point of the polyester. 

The rigid urethane foam concept with integral skins has also found considerable interest in the automotive industry for exterior body parts, such as engine or trunk compartment lids, fenders and even full roofs. These parts can be reinforced with metal inserts where necessary or hinges and fasteners can be molded in for ready mounting. 

After the production of polybutadiene, the automotive industry developed very rapidly. Car tyres, interior and exterior parts of cars could now be produced from artificial rubber. 

Surface Quality. Class "A surface (after painting) is considered by the automotive industry as their first requirement for an exterior part. Comparing the surface quality of several reinforcements in RRIM urethane panels, it was found by visual examination that the best surface quality was the glass flakes and the worst was the integral chopped strands. Milled fiber is slightly worse than glass flakes, but it is still considered a "Class A" surface. 

Emphasis on reaction injection-molding (RIM) technology in the automotive industry to produce automotive exterior parts has created a large potential for thermoset polyurethane elastomers. Reaction injection molding, originally known as reaction casting, is a rapid, one-step process to produce thermoset polyurethane products from liquid monomers. In this process liquid monomers are mixed under high pressure prior to injection into the mold. The polymerization occurs in the mold. Commercial RIM... 

Thus, in the automotive industry, long fibre thermoplastic (LFT) composites are used to produce underbody panels, instrament panel carriers, front end modules, battery trays, sunroof beams, mirror brackets, fuel rails, door modules, seat stmc-tures, convertible header bows, door plate carriers, roof and trunk lids, exterior claddings, skid plates, running boards, step assists, front-end carriers, bumper beams, lift gates, spare wheel tubs and other stmctiual parts (Vaidya, 2011). 

Over the years, the transportation industry has incorporated more and more composite materials into its vehicles. The automotive industry has used composites for exterior body panels, e.g. hoods, fascias, hatches and doors, as well as under the hood and stmctural reinforcements. The truck industry followed, by introducing composites for hoods, doors, roofs, bumpers and fairings. This paper will focus on the advancements made in composite rrraterials, from hand-spray up open molded parts to the various improvements in sheet nrolding compounds to liqrtid molded resin rrraterials. It will concentrate on parts used in the trucking industry and how quality, especially in cosmetic and surface properties, has improved over the years. 

Poly(butylene terephthalate) (PBT) (1) resins are semicrystalline thermoplastics used in a wide variety of applications, most commonly in durable goods that are formed by injection molding. Applications include electronic and communications equipment, computers, televisions, kitchen and household appliances, industrial equipment, lighting systems, gardening and agricultural equipment, pumps, medical devices, food handling systems, handles, power and hand tools, bobbins and spindles, and automotive parts in both under-the-hood and exterior applications. Additionally, PBT is very widely used to form electrical connectors. PBT, through its many blended products, can be tailored to suit numerous applications. 

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