Anisotropic dispersion polymerization of N‐(4‐aminobenzoyl)–caprolactam in polymer melts

Abstract

AbstractWhen N‐(4‐aminobenzoyl)–caprolactam (PAC) is injected into polymer melts, dispersions of anisotropic polyaramide particles with average diameters of 100–400 nm and aspect ratios of 5–10 are formed within few minutes. At 200°C PAC dispersion polymerization yields caprolactam and predominantly poly(p‐phenylenebenzamide), whereas with increasing polymerization temperatures PAC ring‐opening polymerization accounts for the incorporation of 6‐aminocaproic acid units into the polyaramide backbone. Covalent bond formation between microparticle surfaces and functional groups of the matrix polymer provides excellent interfacial adhesion and stabilizes the anisotropic polyaramide microparticle dispersions. This in situ PAC dispersion polymerization during melt processing, producing polyaramide‐whisker reinforced thermoplastics, represents a versatile route to organic microcomposites exhibiting improved stiffness and strength.