Clad polymer buffer rods for polymer process monitoring

Clad polymer buffer rods consisting of a polyetheretherketone (PEEK) core and a cladding made of a heat resistance epoxy-aluminum composite are presented. The core has a uniform diameter or a taper shape. Ultrasonic measurement results indicate that the ultrasonic signal strength and signal to noise ratio of these clad rods are better than those of the non-clad PEEK rods for both longitudinal and shear waves because of the improved ultrasonic wave guidance in the core. Comparisons of these rods with those made of polymide and high-density polyethylene are given. Applications of these buffer rods for ultrasonic monitoring of polymer extrusion at temperatures up to 200 degreesC and pressures up to 180 psi are demonstrated. The monitoring results also reveal that within certain operating temperature and pressure range, clad polymer buffer rods show advantages over clad steel buffer rods. Crown Copyright (C) 2001 Published by Elsevier Science B.V. All rights reserved.