ABSTRACT

The curing of polyurethane foam involves complex changes – changes from mobile liquid to rubbery, or even rigid, product are accompanied by changes in density and sample size. All these take place under conditions where there may be rapid changes in temperatures. The ability to profile and record such events has traditionally required skilled, often time-consuming observation. However where non-foaming systems are concerned, technologists have had access to a variety of instrumentation that can monitor changes in viscosity or the development of elastic character. This facility is now available for foamed polyurethane, with a development of the Rapra Vibrating Needle Curemeter (VNC). The development involves the integration of the existing instrument with detectors for rise and exotherm. Continuous response/time plots are thus produced; a response for the development of visco-elastic properties being added to those for height and temperature. The result is a unique fingerprint for the cure which is amenable to storage and archiving. This paper will show the outputs for foaming PU systems and discuss some of the insights accessible with this powerful tool.