Twaron (a brand name of Teijin Aramid) is a para-aramid. It is a heat-resistant and strong synthetic fibre developed in the early 1970s by the Dutch company AKZO, division ENKA, later Akzo Industrial Fibers. The research name of the para-aramid fibre was originally Fiber X, but it was soon called Arenka. Although the Dutch para-aramid fiber was developed only a little later than DuPont's Kevlar, introduction of Twaron as a commercial product came much later than Kevlar due to financial problems at the AKZO company in the 1970s.
Contents
History
This is a chronology of the development of Twaron:
Polymer preparation
Twaron is a p-phenylene terephthalamide (PpPTA), the simplest form of the AABB para polyaramide. PpPTA is a product of p-phenylene diamine (PPD) and terephthaloyl dichloride (TDC). To dissolve the aromatic polymer Twaron used a co-solvent of N-methyl pyrrolidone (NMP) and an ionic component (calcium chloride CaCl2) to occupy the hydrogen bonds of the amide groups. The invention of this specific process was done in 1974 at AKZO Research Laboratory in Arnhem by a team consisting of Leo Vollbracht, Teun Veerman (assistant of Leo Vollbracht) and Wim Engelhard (trainee, who actually discovered NMP as the appropriate solvent to keep the growing polymer as long as possible in solution; he also discovered that high speed mixing of PPD and TDC was necessary to obtain a sufficiently long polymer chains). The patent of the newly discovered process route led to a patent war between AKZO (Fibre X) and DuPont (Fibre B) as Dupont initially used the carcinogenic HMPT (hexamethylphosphoramide). Despite heavy research DuPont now also applies the AKZO patent for their Kevlar process and use the less hazardous NMP.
Spinning
After the production of the Twaron polymer in Delfzijl, the polymer is brought to Emmen, where fibres are produced by spinning the dissolved polymer into a solid fibre from a liquid chemical blend. Polymer solvent for spinning PPTA is generally 100% anhydrous (water free) sulfuric acid (H2SO4). The polymer is dissolved by mixing frozen sulfuric acid in powder form with the polymer in powder form and gently heating the mixture. This process, which differs from the more difficult DuPont process, was invented by Henri Lammers and patented by AKZO.
Industrial uses
Twaron is a para-aramid and is used in automotive, construction, sport, aerospace, military and industry applications, e.g., "bullet-proof" body armor, fabric, and as an asbestos substitute.