Thermoplastics are polymers which flow when molten and can be formed into shapes which are retained upon cooling. A wide range is available, from low-cost commodity plastics (e.g., PE, PP) to high cost engineering thermoplastics (e.g., PEEK) and fluoropolymers (e.g., PTFE). The latter is one of the few thermoplastics which is not melt-processable. Plastics can be divided into those which are partially crystalline and those which are completely amorphous. The former tend to be stiffer and have better fluid resistance. Hence the major thermoplastics used in offshore oil & gas applications are semi-crystalline: for example, HDPE, PP, PA 11, PVDF, PEEK, PTFE, PPS.

MERL provides a range of testing and polymer research services for thermoplastic performance characterisation, including:

Mechanical (static, time-dependent)
Tensile stress/strain, creep, stress relaxation, fracture toughness

Mechanical (dynamic)
Crack growth, fatigue

Fluid resistance
Immersion testing (compatibility), HP gas permeation (Q, D, s)

Chemical resistance
Solvents, hydrocarbons, sour gas, alcohols, acids.

Gripping of test piece machined from pipe

Polyimide after exposure to methanol at high temperature

Stress-strain curves vs. temperature for a fluoroplastic