The modulus build-up and relative density evolution during the reactive foaming of four standard polyurethane formulations was monitored in-situ by Dynamic Mechanical Analysis (DMA) with a customised set-up in parallel plate geometry. The modulus increased from 0.01 MPa in the first minutes to over 1.2 MPa within 20 min. The set-up also enabled the recording of vitrification followed by curing times. These typically occur within 3 min of each other. The results of DMA are corroborated by measurements of the reaction kinetics with Infrared Spectroscopy. This goes to show that the modulus remains nearly unchanged during the stage of swiftest isocyanate conversion, while the point of gel conversion is accompanied by their increase.

在四种标准聚氨酯配方的反应发泡过程中，模量建立和相对密度演变通过动态机械分析 (DMA) 与平行板几何形状的定制设置进行原位监测。模量从最初几分钟的 0.01 MPa 增加到 20 分钟内的 1.2 MPa 以上。该设置还能够记录玻璃化和固化时间。这些通常发生在彼此的 3 分钟内。DMA 的结果通过用红外光谱测量反应动力学得到证实。这表明在异氰酸酯转化最快的阶段模量几乎保持不变，而凝胶转化点伴随着它们的增加。