Melt Modification of Polyamides

Abstract

Polyamides are engineering plastics with a wide application area. The first part of this contribution deals with the degradation of polyamides including the discussion of degradation mechanism. The fast, controlled degradation reaction in the melt occurs upon addition of carboxylic acid and carboxylic anhydride compounds. Oligoamides with a defined molecular weight and a narrow molecular weight distribution could be obtained in such a fast melt modification reaction by reactive extrusion. The general degradation mechanism $$ {\text{R {-} COOH + P}}{{\text{A}}_1}{\text{{-}CO{-}NH{-}P}}{{\text{A}}_2} \to {\text{R {-} CO\ NH{-}P}}{{\text{A}}_2}\ {\text{ +\ P}} {{\text{A}}_1}{\text{ {-} COOH}} $$ includes “risk and chances” for reactive extrusion processes and is transferred to several polymer processing systems. By reactive extrusion new polymer materials could be obtained e.g. new graft and block copolymers. It was also possible to transfer chemical reaction into injection moulding processes to increase the bond strength in two-component injection and sandwich moulding processes or to modify the surface properties during an injection moulding process.