Structure, Nanomechanics and Dynamics of Dispersed Surfactant-Free Clay Nanocomposite Films
Xiao Zhang, Jing Zhao, Chad R. Snyder, Abdullah Al-Enizi, Ahmed Eltazahry, Alamgir Karim
Using additives to tailor the performance of polymeric materials is perhaps one of the most important aspects for producing materials of advanced applications. The exploitation of nanoparticle dispersion strategies have been broadly investigated for tuning polymer morphologies and properties. Of particular interest is the study of clay filled polymer nanocomposites due to the abundant resource in nature, platelet structure bearing high aspect ratio, high efficiency, and promising ion-exchange capacity of clay minerals. The current work presents a new approach to achieve high quality dispersion of surfactant-free nanoclay particles in sub-micron thin films despite the structural dissimilarity and the absence of organic modifier. Natural Montmorillonite particles, Na+ Cloisite, were dispersed in thin films of polycaprolactone (PCL) through a flow coating technique assisted by ultra-sonication. Wide angle X-ray scattering (WAXS), Grazing-incidence wide angle X-ray scattering (GI-WAXS), and transmission electron microscopy (TEM) were used to confirm the level of dispersion. These characterization techniques are in conjunction with its nanomechanical properties via strain-induced buckling instability for modulus measurements (SIEBIMM), a high throughput technique to characterize thin film mechanical properties. The linear strengthening trend of the elastic modulus, increased from 219 MPa to 235MPa, was fitted with Halpin-Tsai (HT) model, correlating the nanoparticle geometric effects and mechanical behaviors based on continuum theories. The overall aspect ratio (AR) of 3.1, obtained through HT model fitting, is in reasonable agreement with digital microscope image analysis showing AR values ranging from 2 to 3. Moreover, glass transition behaviors of the composites were characterized using broadband dielectric relaxation spectroscopy. A series of segmental relaxation time-temperature data indicate that the well-dispersed clay tactoids have a prominent influence on...
, Zhao, J.
, Snyder, C.
, Al-Enizi, A.
, Eltazahry, A.
and Karim, A.
Structure, Nanomechanics and Dynamics of Dispersed Surfactant-Free Clay Nanocomposite Films, Polymer Engineering and Science, [online], https://doi.org/10.1002/pen.24693, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=920427
(Accessed December 5, 2023)