Extrusion freeforming of Nylon 6 materials

A modified Nylon 6 formulation, developed originally for reaction injection moulding, has been used to freeform small parts. Liquid monomer is deposit ed as a fine stream from computer-controlled writing head and polymerizes o n a heated plate as the part is built up. This is the first example of rapi d prototyping of a linear polymer by direct polymerization. Nylon was chose n for this work because it attains good mechanical properties at relatively low molecular weights, so limiting the extent of chain propagation necessa ry. Freeformed bars were made with a strength of 75 MPa and tensile modulus of 2.3 GPa. (C) 1999 Elsevier Science Ltd. All rights reserved.