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

<p>Knowledge of the evolution in the mechanical properties of a curing polymer matrix is of great importance in composite parts or structure<br>fabrication. Conventional rheometry, based on small amplitude oscillatory shear, is limited by long interrogation times. In rapidly evolving<br>materials, time sweeps can provide a meaningful measurement albeit at a single frequency. To overcome this constraint, we utilize a combined<br>frequency- and amplitude-modulated chirped strain waveform in conjunction with a homemade sliding plate piezo-operated rheometer (PZR)<br>and a dual-head commercial rotational rheometer (Anton Paar MCR 702) to probe the linear viscoelasticity of these time-evolving materials.<br>The direct controllability of the PZR, resulting from the absence of any kind of firmware and the microsecond actuator-sensor response<br>renders this device ideal for exploring the advantages of this technique. The high frequency capability allows us to extend the upper limits of<br>the accessible linear viscoelastic spectrum and, most importantly, to shorten the length of the interrogating strain signal (OWCh-PZR) to subsecond<br>scales, while retaining a high time-bandwidth product. This short duration ensures that the mutation number (NMu) is kept sufficiently<br>low, even in fast-curing resins. The method is validated via calibration tests in both instruments, and the corresponding limitations are discussed.<br>As a proof of concept, the technique is applied to a curing vinylester resin. The linear viscoelastic (LVE) spectrum is assessed every<br>20 s to monitor the rapid evolution in the time and frequency dependence of the complex modulus. Comparison of the chirp implementation,<br>based on parameters such as duration of the experiment, sampling frequency, and frequency range, in a commercial rotational rheometer with<br>the PZR provides further information on the applicability of this technique and its limitations. Finally, FTIR spectroscopy is utilized to gain<br>insights into the evolution of the chemical network, and the gap dependence of the evolving material properties in these heterogeneous<br>systems is also investigated</p>