About Plastics

Plastics and plastic materials are organic, synthetic or processed polymers that are supplied as raw materials or stock shapes. They typically consist of thermoplastic or thermosetting resins and can be made into many forms. Stock shape forms include sheets, plates, rods, tubes, films, or extruded profiles. Often, thermoplastic resins are supplied as pellets for feeding into molding machines or extrusion presses. Thermosets may be supplied as two-part liquid resins such as epoxies, or as a non-flowing mass premixed with fiber reinforcement. Polyester bulk molding compounds (BMC) are an example of this latter form. Water-based resins, water-born resins and latex products are plastics and plastic materials that consist of resin or polymer droplets that are dispersed and suspended in a water carrier or solvent.

There are many material types and grades for plastics and plastic materials. Cure type or cure technology is also an important consideration. Material types include monomers and intermediates, binders and base polymers, composite materials, thermoplastic materials, thermosets and crosslinked materials, semi-finished shapes, fabricated shapes, and resins and compounded raw materials such as pellets and liquids. Electrical and electronic materials, optical grade materials, and self-lubricated or bearing-grade plastics and plastic materials are also available. With regard to cure type or cure technology, choices include air setting or film drying, anaerobic, thermoplastic or hot melt, thermosetting or cross-linking, room-temperature curing or vulcanizing, and pressure sensitive adhesive (PSA). Plastics and plastic materials that are cured with ultraviolet light (UV) are also available, as are reactive resins, single-component products, and two-component systems.

With plastics and plastic materials, the term “material system” refers to the chemical or polymer system type. Examples include acetal, acrylonitrile-butadiene-styrene (ABS), acrylic, bismaleimide (BMI), cellulosic, epoxy (EP), ethylene copolymer, fluoropolymer, ionomer, liquid crystal polymer (LCP), and ketones such as polyaryletherketone and polyetheretherketone (PEEK). Choices for plastics and plastic materials also include phenolics and formaldehyde resins, polyamide, polyamide, polyimide, polybutadiene, polycarbonate (PC), polyethylene, polyethylene terphthalate (PET), and polybutylene terphthalate (PBT). In addition, plastics and plastic materials may contain polyester, vinyl ester, polyether block amide (PEBA) resins, polyetherimide, polyolefin, polyphenylene oxide (PPO), polypropylene (PP), polysulphide, polysulphone, or polyphthalamide. Products made of silicone, styrene, styrene copolymer, and vinyl are also available.

Plastics and plastic materials carry many different specifications. Categories include material type or grade, cure type or technology, material system, and (if applicable) filler material. Thermal properties, mechanical properties, electrical and optical properties, and processing and physical properties are also important considerations. Thermal properties for plastics and plastic materials include use temperature, deflection temperature, thermal conductivity and coefficient of thermal expansion (CTE). Tensile strength, tensile modulus, and elongation are important mechanical parameters. Electrical and optical properties include electrical resistivity, dielectric strength, dielectric constant or relative permittivity, index of refraction, and transmission. Viscosity, melt flow index (MFI) and water absorption are processing and physical properties to consider when selecting plastics and plastic materials.

(Article Courtesy of GLOBALSPEC – The Engineering Search Engine)




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