High-performance plastics

[2] The improvement of mechanical properties and thermal stability is and has always been an important goal in the research of new plastics.

Since the early 1960s, the development of high-performance plastics has been driven by corresponding needs in the aerospace and nuclear technology.

[3] Synthetic routes for example for PPS, PES and PSU were developed in the 1960s by Philips, ICI and Union Carbide.

Since electrophilic synthesis has in general the disadvantage of a low selectivity to linear polymers and is using aggressive reactants, the product could hold only a short time on the market.

For this reason, the majority of high-performance plastics is nowadays produced by polycondensation processes.

[1] Some of their diverse applications include: fluid flow tubing, electrical wire insulators, architecture, and fiber optics.

Based on the properties of the standard plastics some improvements of mechanical and thermal features can already be accomplished by addition of stabilizers or reinforcing materials (glass and carbon fibers, for example) or by an increase in the degree of polymerization.

The thermal degradation occurs primarily by a statistical chain scission; depolymerization and removal of low molecular weight compounds are playing only a minor role.

Poly(p-phenylene) can serve as an example, it consists exclusively of aromatics and provides extremely stability, even at temperatures above 500 °C.

[6] Fluorine-containing polymers are, however, not suitable to serve as construction material due to poor mechanical properties (low strength and stiffness, strong creep under load).

This is because semi-crystalline polymers have, in addition to a glass temperature Tg, a crystallite melting point Tm, which is usually much higher.