Holt_09544089211026549.pdf (1.84 MB)

Monitoring the continuous manufacture of a polymeric foam via a thermokinetic-informed acoustic technique

Download (1.84 MB)
journal contribution
posted on 01.06.2021, 09:10 by Joseph Holt, Carmen TorresCarmen Torres, Paul ConwayPaul Conway
Polymer foams are difficult to characterise due to rapidly evolving physical features from liquid to porous solid. Swift changes in volume, porosity and moduli render many techniques challenging for the characterisation of the foam curing during a manufacturing process. A technique that employs the longitudinal speed of sound of an ultrasonic signal, informed by a thermokinetic model, is proposed as an in-situ, in-line, non-destructive and continuous monitoring tool during production of rigid polyurethane foams. This study demonstrates that speed of sound measurements are suitable for: (i) continuous characterisation of different foaming stages in the polymer reaction and curing; (ii) determining the degree of cure for the continuous monitoring of foams, and (iii) predicting mechanical properties (i.e. stiffness and Poisson’s ratio) of cured foam samples. The validity of this monitoring technique is confirmed by comparison with well-established methods that use physical characteristics (e.g. expansion rate, electrical properties), thermo-kinetic models and mechanical testing. This method positions itself as a monitoring tool and convenient method for determining material stiffness during production.


EPSRC Centre for Doctoral Training in Embedded Intelligence

Engineering and Physical Sciences Research Council

Find out more...

Far UK Ltd



  • Mechanical, Electrical and Manufacturing Engineering

Published in

Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering


SAGE Publications


VoR (Version of Record)

Rights holder

© The authors

Publisher statement

This is an Open Access Article. It is published by Sage under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

Acceptance date


Publication date









Dr Carmen Torres-Sanchez. Deposit date: 28 May 2021