Dataset related to "High-frequency optimally windowed chirp rheometry for rapidly evolving viscoelastic materials: Application to a crosslinking thermoset" (Q6704340)

Knowledge of the evolution in the mechanical properties of a curing polymer matrix is of great importance in composite parts or structurefabrication. Conventional rheometry, based on small amplitude oscillatory shear, is limited by long interrogation times. In rapidly evolvingmaterials, time sweeps can provide a meaningful measurement albeit at a single frequency. To overcome this constraint, we utilize a combinedfrequency- and amplitude-modulated chirped strain waveform in conjunction with a homemade sliding plate piezo-operated rheometer (PZR)and a dual-head commercial rotational rheometer (Anton Paar MCR 702) to probe the linear viscoelasticity of these time-evolving materials.The direct controllability of the PZR, resulting from the absence of any kind of firmware and the microsecond actuator-sensor responserenders this device ideal for exploring the advantages of this technique. The high frequency capability allows us to extend the upper limits ofthe accessible linear viscoelastic spectrum and, most importantly, to shorten the length of the interrogating strain signal (OWCh-PZR) to subsecondscales, while retaining a high time-bandwidth product. This short duration ensures that the mutation number (NMu) is kept sufficientlylow, even in fast-curing resins. The method is validated via calibration tests in both instruments, and the corresponding limitations are discussed.As a proof of concept, the technique is applied to a curing vinylester resin. The linear viscoelastic (LVE) spectrum is assessed every20 s to monitor the rapid evolution in the time and frequency dependence of the complex modulus. Comparison of the chirp implementation,based on parameters such as duration of the experiment, sampling frequency, and frequency range, in a commercial rotational rheometer withthe PZR provides further information on the applicability of this technique and its limitations. Finally, FTIR spectroscopy is utilized to gaininsights into the evolution of the chemical network, and the gap dependence of the evolving material properties in these heterogeneoussystems is also investigated