Description

Polymer and plastic composites are plastics which are strengthened with fibers, fillers, particulates, powders and other matrix reinforcements to provide improved strength and/or stiffness. Examples include fiber reinforced plastics (FRPs), sheet molding compounds (SMCs), bulk molding compounds (BMCs), pre-preg materials, and fabricated composite parts.

Types of Polymer Composites

The GlobalSpec SpecSearch Database contains listings of a variety of different polymer matrices. Some of the most common are epoxy, polyacetal, PEEK, fluoropolymers, and phenolics.

Epoxy resins exhibit high strength and low shrinkage during curing. They are known for their toughness and resistance to chemical and environmental damage. Most are two-part resins cured at room temperature. Depending on the formulation, epoxy resins are used as casting resins, potting agents, resin binders, or laminating resins in fiberglass or composite construction. They are also used as encapsulates, electrical conductors in microelectronic packaging, and adhesives in structural bonding applications.

Polyacetal or polyoxymethylene (POM) is a thermoplastic used in precision parts that require high stiffness, low friction, and excellent dimensional stability. It provides a higher strength material compared to polyethylene-type polymers; however, polyacetal materials are susceptible to oxidation at elevated temperatures. DuPont’s Delrin^® is a common polyacetal engineering resin that is also used to mold plastic parts.

PEEK or polyether ether ketone is a colorless organic polymer thermoplastic. It has excellent mechanical and chemical resistance properties that are retained at high temperatures. It is highly resistant to thermal degradation as well. It is used extensively in the aerospace, automotive, electronic, and chemical process industries.

Fluoropolymers including polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) are used in applications requiring superior chemical resistance. PTFE is used in applications requiring superior chemical resistance or low friction. 

Phenolics are thermosetting molding compounds and adhesives that offer strong bonds and provide good resistance to high temperatures. Phenolic resin adhesives made from chemicals of the phenol group and formaldehyde are generally the most durable. Phenolic resins are available in liquid, powder, and film form. Special phenolic resins are available that harden at moderate temperatures when mixed with suitable accelerators. Urea formaldehyde resins can harden rapidly at moderate temperatures, but generally do not have the properties of phenolic resins. Melamine resins have excellent dielectric properties. 

Matrix Reinforcements

Products may be strengthened with fibers, fillers, particulates, powders and other matrix reinforcements to provide improved strength and/or stiffness. Fibers are usually chopped, wound or woven and made of materials such as fabric, metal, glass, or fiberglass. Particulates vary in terms of shape and size. Powders are usually made of carbon, graphite, silicates, ceramics, and other organic or inorganic materials. Some matrix reinforcements provide improved electrical conductivity. Others offer improved thermal conductivity. 

Thermoplastic Composites

Thermoplastic composites include glass mat thermoplastics (GMT), weave-reinforced GMTs, low-density composites, and composite sandwich panels. GMTs are compression-molded thermoplastics that are used in place of metals such as aluminum or steel, plywood, or even engineered materials. Weave-reinforced GMTs are synthetic fabrics that are used as automotive materials to provide enhanced protection of a car’s underbody on poorly surfaced roads.

Product Features

Polymer and plastic composites vary in terms of features. Products that are designed for electrical and electronics applications often provide protection against electrostatic discharge (ESD), electromagnetic interference (EMI), and radio frequency interference (RFI). Materials that are electrically conductive or resistive are also available. Polymer and plastic composites that use a phase change provide enhanced thermal characteristics.