After WWII, U.S. automakers rapidly expanded the use of synthetic plastics to cut cost/weight, enable new styling, and improve corrosion resistance. Below are the major plastics, what they were used for, and the key U.S. companies that supplied them or commercialized them in cars (roughly late‑1940s through the 1960s).
Big families of plastics and where they showed up
Phenolics (phenol‑formaldehyde, “Bakelite”-type thermosets)
Typical parts: distributor caps/rotors, electrical switchgear, knobs, small under‑hood insulators, some interior hardware.
Why used: heat resistance, electrical insulation, dimensional stability.
Major suppliers: Bakelite Corporation (later part of Union Carbide), General Electric (phenolic molding compounds), and major compounders/molders supplying Detroit.
Urea‑formaldehyde and melamine‑formaldehyde (thermosets)
Typical parts: interior knobs, handles, some trim pieces, steering-column/under‑dash small parts (especially where a hard, glossy surface was desired).
Why used: good surface finish, colorability, stiffness (but more brittle than later plastics).
Major suppliers: resin producers such as American Cyanamid and others that sold molding compounds into automotive supply chains.
PVC (polyvinyl chloride) — rigid and plasticized
Typical parts: vinyl upholstery, door panels, dash pads/skins, wire insulation, undercoating/sealers, some exterior trim strips.
Why used: cheap, flexible (when plasticized), easy to form, good for skins/coatings.
Major suppliers: B.F. Goodrich (a pioneer in PVC), Union Carbide, and Dow (vinyl-related chemicals), with upholstery/trim made by Tier suppliers.
Polystyrene (GPPS/HIPS)
Typical parts: interior trim, knobs, bezels, some instrument-panel components (often later replaced by tougher plastics).
Why used: low cost, easy injection molding; HIPS improved impact resistance.
Major suppliers: Dow Chemical (major polystyrene producer), Koppers (styrenics), and others.
ABS (acrylonitrile‑butadiene‑styrene)
Typical parts: interior trim, instrument-panel parts, grilles and bezels, some wheel covers and decorative components (varied by maker).
Why used: tougher than polystyrene, good surface finish, plateable grades enabled “chrome-like” trim.
Major suppliers: Borg-Warner (notably via Cycolac ABS), plus resin/compound suppliers feeding Detroit.
Acrylic (PMMA, e.g., Plexiglas/Lucite)
Typical parts: lenses, light covers, some interior transparent pieces; occasionally specialty glazing applications.
Why used: optical clarity, weathering resistance, styling freedom.
Major suppliers/brands: Rohm & Haas (Plexiglas), DuPont (Lucite).
Polyethylene (PE) and polypropylene (PP)
Typical parts: wire/cable insulation (PE), fluid bottles and small containers, later more interior parts (PP grew strongly in the 1960s).
Why used: chemical resistance, low cost, toughness; PP especially for lightweight interior components.
Major suppliers: Union Carbide, Dow, Hercules (early PP in the U.S.), and others.
Polyurethane (PU) foams (flexible and semi-rigid)
Typical parts: seat cushions, armrests, headliners, energy-absorbing interior pads; later bumper cores and more.
Why used: comfort, energy absorption, moldability into complex shapes.
Major suppliers: chemical systems from Mobay (Monsanto/Bayer JV), Dow, DuPont, and foam/seat suppliers.
Fiberglass-reinforced plastics (FRP) — polyester resin + glass fiber (thermoset composite)
Typical parts: body panels on specialty cars, front ends, hoods, decklids; also truck components and some structural-ish panels.
Why used: corrosion resistance, complex shapes without expensive steel dies at low volume.
Iconic U.S. use: Chevrolet Corvette (1953) popularized mass-market awareness of fiberglass bodies.
Major resin/fiber players: Owens-Corning (glass fiber), PPG (glass), DuPont and Reichhold (polyester resins/chemicals), plus many molders.
Engineering thermoplastics emerging by the 1960s
- Nylon (polyamide): under‑hood parts, bushings, gears, fasteners; valued for wear resistance and heat tolerance. DuPont (Nylon) was central.
- Acetal (POM, e.g., Delrin/Celcon): small gears, latches, fuel-system and window hardware. DuPont (Delrin) and Celanese (Celcon). These materials expanded as under‑hood temperatures and part complexity increased.
Automakers and “where it showed”
- GM: early high-visibility composite use via the Corvette’s fiberglass body; broad interior plastics adoption across Chevrolet/Pontiac/Olds/Buick/Cadillac as dashboards and trim became more molded and styled.
- Ford and Chrysler: heavy adoption of vinyl (PVC) interiors, molded trim, and later foams and ABS/engineering plastics as the 1950s–60s styling race intensified.
- AMC/Studebaker/others: often used plastics strategically to reduce tooling cost and differentiate interiors, especially in lower-volume models.
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