Body panels, automotive polymers

The polyDCPD has good flexural modulus and exceUent impact resistance (61). Current uses for polyDCPD are in golf carts, snowmobiles, and automotive bumpers (62). The polymer is viewed as having a high potential, especially in automotive body panel appHcations. 

Step growth polymerization can also yield highly crosslinked polymer systems via a prepolymer process. In this process, we create a prepolymer through a step growth reaction mechanism on two of the sites of a trifunctional monomer. The third site, which is chemically different, can then react with another monomer that is added to the liquid prepolymer to create the crosslinked species. We often use heat to initiate the second reaction. We can use this method to directly create finished items by injecting a mixture of the liquid prepolymer and additional monomer into a mold where they polymerize to create the desired, final shape. Cultured marble countertops and some automotive body panels are created in this manner. 

Low-profile additives, which control shrinkage, have emerged as a distinct science and class of additive. Unsaturated polyester resins, as do all thermosetting polymers, shrink when cured. Low-profile additives are a major class of additives used to control shrinkage, which vastly improves surface quality. This science is credited with the opening of automotive markets where surface quality is of prime importance. In exterior automotive body panels, Class A surfaces are required for market acceptance. 

Xycon Hybrid Resin. [Amoco] Two-component polymer thermoset for truck-body panels, after-market automotive parts, recreational vehicles, outdoor equip., tubs and showers, elec, parts. 

Highly compatible polymer blends of PPE and linear polyester resins provide beneficial improvements in the chemical resistance required for automotive applications. Such automotive applications include molded thermoplastic body panels. Foamable compositions of PPE resins are particularly suited as sources of lightweight structural substitutes for metals, especially in the automotive industry. 

Other, nanometer-scale forms of carbon, such as nanotubes and graphenes, have been proposed as ESD fillers, though their early use may be greater with engineering polymers. Carbon nanotubes (CNTs), in diameters of lO-lOOnm, can induce the conductivity needed for electrostatically paintable plastic automotive body panels, for example. They are also said to be replacing carbon black and fiber in small, detailed electronics applications [6-5]. 

The nano-level dispersion of clay in thermoplastic olefin (TPO) polymer has potentially provided a platform for its use in automotive body panels of Volvo cars. The governing factors are light weight, consistent physical and mechanical properties, improved aesthetic appearance, improved wear resistance, and low temperature ductility. Recyclability of nano-clay incorporated thermoplastic olefin nanocomposites has provided an opportunity for their use in step assists and trim and panel in Hummer cars. 

The need to balance superior stiffness and toughness over that of existing ABS led to the introduction of PC/ABS blends in the automotive industry. Polymer blends have always played an important role in automotive applications by providing additional properties that cannot be achieved with only a single material. Based on its versatility, PC/ABS blends are considered a mainstay engineering material for applications such as automotive IPs and body panels. 

Biobased polymers are also being used to produce automotive parts. For example, soy-resin body panels are used to replace steel doors in John Deere tractors (Figure 13.4). Tires infused with com are produced by Goodyear and used in Ford Fiestas in Europe [29]. These tires are found to have a lower rolling resistance, which means a higher fuel mileage. 

In the automotive market, appearance is often a significant functional and aesthetic requirement influencing polymer selection. For example, with large exterior body parts, such as fascia and body panels, a surface finish that matches the adjacent sheet metal is an absolute requirement dictated by consumer expectations. This consumer preference for Class A exterior surface quality has several times thwarted attempts to eliminate current painting processes, which tend to be costly and environmentally unfriendly. Pigmented, molded-in-color (MIC) fascia and claddings have only been successful, at this time, on lower line and... 

Polyurethane Polyurethane adhesives are created from isocyanates. Often used for bonding polymers (especially elastomers) to metal. A specific example is the bonding of SMC that is used in automotive body panels to steel. 

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