Non-Destructive Investigation of Dispersion, Bonding, and Thermal Properties of Emerging Polymer Nanocomposites Using Close-Up Lens Assisted Infrared Thermography

Abstract

Polymer nanocomposites possess unique sets of properties that make them suitable for different applications, including structural and flame-retardant material, electromagnetic wave reflector, sensors, thin film transistor, flexible display, and many more. The properties of these nanocomposite are dependent on nanofiller dispersion and bonding with polymer matrix (i.e. particle-matrix interaction). Thermography is a non-destructive method that may be used to gain insight into dispersion and particle-matrix interaction. Infrared (IR) radiation emitted from these nanomaterial polymer composite depends on the emissivity of the individual components. In addition, during flash heating and cooling, different thermal conductivity of components in the nanocomposite can influence pixel intensity differently in the IR image or video being captured. We have used an economical mid wavelength IR camera Fluke RSE600 equipped with a close-up macro lens and algorithm based on MATLAB image processing toolbox to analyse dispersion, voids and thermal diffusivity of patented graphene polymer nanocomposite materials (G-PMC) in micro-scale. These G-PMCs can act as a standard material to determine the potential of our IR thermography technique due to their homogeneity and lack of impurity due to unique fabrication process. Thermal diffusivity and dispersion of nanoparticles in our G-PMCs was estimated after irradiation with a xenon flash lamp by spatially mapping transient IR radiations from different G-PMCs using the Fluke RSE600 thermal imager. Results from thermography experiments were compared with scanning electron microscope (SEM) and Raman spectroscopy results. Micro-scale thermography was able to detect millimetre scale thermal diffusivity variation in the injection molded G-PMC samples and relate it to change in dispersion of nanofillers, unlike SEM and Raman, where micro-scale measurements could not determine the reason behind millimetre scale property variation. We believe this low cost, fast, micro-scale, non-destructive technique will provide valuable insight into functional polymer nanocomposite fabrication and corresponding electrical and thermal properties.

Multifunctional Graphene–Polymer Nanocomposite Sensors Formed by One-Step In Situ Shear Exfoliation of Graphite

“…No filler agglomeration was observed from the SEM images. This uniform distribution of GNFs within PSU is similar to our previous work investigating in situ exfoliation of graphite into GNFs within an Ecoflex 00-30 using an infrared thermography approach [30,31]. The original graphite flake diameter was ~300 µm; however, the GNF size measured in SEM images is ~10 µm, indicating a shear-induced fracture across the basal plane resulting in edge sites that are available to form covalent bonds with surrounding polymer molecules.…”

“…The hysteresis (difference in resistance change at the same temperature during heating and subsequent cooling) can be as high as ~20%, whereas in our case it was only 0.42% [23]. Thermal images (from thermal video recording during the entire test) show a uniform temperature profile across the sample area being heated, indicating uniform dispersion of the nanofillers in the polymer composite (Figures 7b and 8b) [30,31].…”

“…Under an external load, the distance between graphene in the composite and the structure of the hexagonal honeycomb will change, resulting in a change in resistance and therefore current flow through the composite sensor [34]. Electrons tunnel or hop from one graphene flake to another (if the filler content is above the percolation threshold in the composite), and that is why the change in distance between graphene flakes changes the resistance to electron flow [31].…”

Automatic dispersion, defect, curing, and thermal characteristics determination of polymer composites using micro-scale infrared thermography and machine learning algorithm

“…For instance, infrared thermography was used by Pantano et al to evaluate the poor dispersion of carbon nanotubes in nanocomposites 19 . Ashraf et al studied the dispersion (quantified as dispersion index) and thermal properties of graphene polymer composites using a close-up lens infrared thermography 20 . Gresil et al studied the thermal diffusivity mapping of graphene-based polymer nanocomposites at a resolution of 200 µm per pixel 21 .…”