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 the production of rigid polyurethane foams. This study demonstrates that speed of sound measurements are suitable for (a) continuous characterisation of different foaming stages in the polymer reaction and curing; (b) determining the degree of cure for the continuous monitoring of foams, and (c) 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.

由于从液体到多孔固体的快速演变的物理特性，聚合物泡沫难以表征。体积、孔隙率和模量的快速变化使许多技术在制造过程中对泡沫固化的表征提出了挑战。在硬质聚氨酯泡沫塑料的生产过程中，提出了一种利用超声波信号的纵向声速（由热动力学模型提供信息）的技术作为原位、在线、非破坏性和连续监测工具。该研究表明，声速测量适用于 (a) 聚合物反应和固化中不同发泡阶段的连续表征；(b) 确定泡沫的连续监测的固化程度，和 (c) 预测机械性能（即刚度和泊松 s 比率）的固化泡沫样品。通过与使用物理特性（例如，膨胀率、电特性）、热动力学模型和机械测试的成熟方法进行比较，证实了这种监测技术的有效性。该方法将自身定位为一种监控工具和一种在生产过程中确定材料刚度的便捷方法。