As previously mentioned, the term "thermoplastic composite" refers to a composite with a thermoplastic material as the matrix.  Thermoplastics commonly used in composites include, but are not limited to, the following:

PE - Polyethylene

PP - Polypropylene

PBT - Polybutylene Terephthalate

PA (nylon) - Polyamide

PPS - Polyphenylene Sulfide

PEI - Polyether Imide

PEKK - PolyEtherKeytoneKeytone

PEEK - PolyEtherEtherKeytone

There are many factors that need to be considered when selecting a thermoplastic matrix.  There are three categories into which most users group their most important criteria:  operating environment (and associated environmental resistance of the matrix), mechanical properties, and cost.   For the operating environment, users are generally concerned with items like operating temperatures and exposure to sun, water, and chemicals.  For mechanical properties, it is items like strength, stiffness, and toughness.

Figure 1:  E-Glass/PP composite spring, resin selection driven by cost requirements.

Making the selection of the appropriate matrix more complicated is the fact that, in general, the choices do not excel in every category.  For example, one material might be inexpensive and have good corrosion resistance, but has a very low glass transition temperature (i.e. the temperature at which the plastic starts to soften and is susceptible to creep).  Another might offer a very high glass transition temperature, but be expensive and have relatively poor hydrolytic stability or solvent resistance.  As you might expect, thermoplastics that have high mechanical properties and that can operate in more varied (aggressive) environments tend to cost more.  Automated Dynamics' staff routinely applies our extensive experience to help customers select the best candidate material for the specific needs of their demanding applications.

Figure 2:  Graphite/PEI composite spring, resin selection driven by high T_g required.

Figure 3:  Graphite/PEEK composite springs, resin selection driven by environmental resistance.