Welding plastics with conducting polymers
Background
Joining of Plastics
The development of intrinsically conductive polymers,
especially polyanilines, provides an opportunity for use of conductive
polymers in welding (joining) of thermoplastics and thermosets. Either
a pure, intrinsically conducting polymer film or a gasket prepared from
a compression-molded blend of the intrinsically conductive polymer and
a powder of the thermoplastic or thermoset to be blended is placed at the
interface between two plastic pieces to be joined. Absorption of microwave
frequency radiation results in heating of the joint and subsequent fusing
(welding). The resulting joint may be as strong as that of the pure compression
molded thermoplastic or thermoset, as illustrated in the figure for a joint
of two high-density polyethylene (HDPE) bars using a gasket of HDPE and
PAN doped with HCl. In this figure, the HDPE bar under tension yields at
a location other than the intrinsically conducting polymer-formed joint.
Dependent upon the chemical composition of the conducting polymer and the
dopants used, the resulting joint may be permanent (i.e., the conducting
polymer in rendered nonconducting during the joining process) or reversible
(i.e., the conducting polymer remaining is sufficiently conducting to allow
subsequent absorption of electromagnetic radiation to heat the joint hot
enough for separation of the parts).
Publications
A.J. Epstein, J. Joo, C.Y. Wu, A. Benatar, C.F. Faisst, Jr., J. Zegarski,
and A.G. MacDiarmid, Polyanilines: Recent Advances in Processing and
Applications to Welding of Plastics, Proc. NATO Advanced Research
Workshop on Applications of Intrinsically Conducting Polymers, 12-15
October 1992, Burlington, VT, edited by M. Aldissi (Kluwer Academic Publishers,
1993), pp. 165-178.
Created by Darren Gebler. Maintained by John Rohrbacher. Last updated
5/30/00.