Revealing nanoscale dynamics during an epoxy curing reaction with x-ray photon correlation spectroscopy

Abstract

The evolution of nanoscale properties is measured during the thermally triggered curing of an industrial epoxy adhesive. We use x-ray photon correlation spectroscopy (XPCS) to track the progression of the curing reaction through the local dynamics of filler particles that reflect the formation of a thermoset network. Out-of-equilibrium dynamics are resolved through identification and analysis of the intensity–intensity autocorrelation functions obtained from XPCS. The characteristic time scale and local velocity of the filler is calculated as functions of time and temperature. We find that the dynamics speed up when approaching the curing temperature (Tcure), and decay rapidly once Tcure is reached. We compare the results from XPCS to conventional macroscale characterization by differential scanning calorimetry (DSC). The demonstration and implementation of nanoscale characterization of curing reactions by XPCS proves useful for future development and optimization of epoxy thermoset materials and other industrial adhesive systems.

From Femtoseconds to Hours—Measuring Dynamics over 18 Orders of Magnitude with Coherent X-rays

“…The dynamics are anisotropic during the recovery process of the printed material, indicating structural alignment on the nanoscale induced by the extrusion and deposition. The dynamics associated with the curing of an industrial epoxy adhesive at different temperatures was investigated by Yavitt et al [115]. Tracer particles have been used to perform the XPCS experiment in SAXS geometry.…”

Heterogeneous dynamics in the curing process of epoxy resins

“…Begam et al studied the kinetics of network formation and dynamics of an egg white gel using XPCS and ultrasmall-angle X-ray scattering, revealing the growth of network mesh size and heterogeneous dynamics 38 . Recently, Koga et al performed XPCS measurements of the thermosetting process of epoxy resins containing some fillers, showing that XPCS is a powerful tool for observing the epoxy dynamics from liquid to solid states 39 . They successfully observed the evolution of the filler’s velocity during the curing process; however, owing to the effect of the densely dispersed fillers, only the ballistic motion was observed throughout the curing process, and they could not discuss the change in the movement, such as the deviation from normal Brownian motion and the fluctuation of dynamics, in detail.…”

20 µs-resolved high-throughput X-ray photon correlation spectroscopy on a 500k pixel detector enabled by data-management workflow

“…More efficient use of the large field of view of the XSPA-500k for XPCS studies can therefore be achieved by operating the XSPA-500k at a detector distance much larger than the current 4 m on beamline 8-ID-I at the Advanced Photon Source (APS), Argonne. An example is the up to 16 m setup on the 11-ID beamline (coherent hard X-ray scattering, CHX) at NSLS-II (Brookhaven, New York, USA) (Yavitt et al, 2020;Johnson et al, 2019;.…”

“…Many of these applications are summarized in recent reviews (Leheny, 2012;Shpyrko, 2014;Sinha et al, 2014;Madsen et al, 2016;Sandy et al, 2018). Partially driven by XPCS-applicable area detectors with increasingly high frame rates (Trapani et al, 2018;Zhang et al, 2020Zhang et al, , 2018Zinn et al, 2018;Pennicard et al, 2018;Redford et al, 2018;Maj et al, 2020;Allahgholi et al, 2019;Poikela et al, 2014) but also by emerging near-diffraction-limited storage rings (DLSRs) (Eriksson et al, 2014), a growing area of interest is XPCS applied to rapidly fluctuating and often weakly scattering soft materials (Vodnala et al, 2018;Mö ller et al, 2019;Chung et al, 2019;Zhang et al, 2019;Dallari et al, 2020;Nigro et al, 2020;Frenzel et al, 2019;Yavitt et al, 2020).…”