Chapter 4: Rigid-chain polymers: Aromatic polyamides, heterocyclic rigid rod polymers, and polyesters

Abstract

In the previous chapters the emphasis was on high-performance fibers/tapes based on flexible chain polymers and in terms of strength and stiffness, the primus inter pares is ultra-highmolecular-weight polyethylene, UHMW-PE. These developments on flexible polymer molecules stem from the 1980s but were preceded by the development of high-performance fibers based on (more) rigid polymer chains, notably the aromatic polyamides or abbreviated (poly)aramids. These fibers were developed in the 1960s/1970s and considered at that time as a major disruptive innovation involving liquid-crystalline behaviour of polymer solutions. In this chapter the developments and future outlook of aramid fibers nowadays well known as Kevlar®/Du Pont and Twaron®/Teijin, will be discussed, as well as aromatic polyesters and rigid rod polymers M5 and PBO. In the last chapter ‘Epilogue’ the properties of aramid vs. PE fibers will be critically compared and discussed in view of current competition in the market notably in the ballistic applications and in ropes (mooring lines).