Study of Glass Transition and Reinforcement Mechanism in Polymer/Layered Silicate Nanocomposites

Abstract

The structure-property relationship of polymer/layered silicate nanocomposites was investigated in this study. Polymer nanocomposites based on completely amorphous poly(hexamethylene isophthalamide) with exfoliated, intercalated, or agglomerated nanoclay morphology were produced and analyzed by X-ray diffraction and transmission electron microscopy. Differential scanning calorimetry measurements were used to characterize the glass-transition behavior. Dynamic mechanical analysis was performed to investigate the nature of the constrained region as the reinforcement mechanism. The modulus enhancement of the organoclay nanocomposites was found to have good linear correlation with the volume of the constrained region. The type of polymer-nanofiller interaction strongly influences the amount and modulus of the constrained region, and both of the latter contribute to the enhancement in the storage modulus of the polymer nanocomposite. The mechanical properties of the constrained region are temperature-dependent. Constrained region models for polymer nanocomposites were proposed on the basis of these results. The constrained volume in amorphous polymer nanocomposites was found to be much less than that in semicrystalline systems.

Preparation and characterization of hybrid nanocomposites based on NBR/Nanoclay/Carbon black

“…Further information can be obtained by studying the constrained polymer volume. The fraction of constrained volume (Ccon) of polymer chains can be used as a proper tool to determine the restricted mobility of polymer chains as a result of crystallinity and polymer filler interactions [21,22]. In rubber-based nanocomposites, due to absence of crystallinity, Ccon can be used as a measure of polymer-filler interactions.…”

Cyclic viscoelastoplasticity of polypropylene/nanoclay composites

“…It is explained by (i) formation of a stable filler network structure in polymer nanocomposites (Wang et al 2006;Su et al 2011), (ii) development of constrained regions where mobility of chains is severely restricted by surrounding clay platelets and their stacks (Zhang and Loo 2009), and (iii) overlapping of interfacial layers of neighboring nanoparticles (Mortezaei et al 2011).…”

A method to improve the mechanical performance of styrene-butadiene rubber via vulcanization accelerator modified silica

“…Polymer molecules are sensitive to the local environment because of the characteristic long-chain morphology [24]. Thus, the T g and normalized change of heat capacity (DC pn ) of polymer at glass transition are important parameters.…”

“…Thus, the T g and normalized change of heat capacity (DC pn ) of polymer at glass transition are important parameters. They provide information about the structural changes of the polymer during the transition [24,25]. Fig.…”

“…Therefore, the DC pn at glass transition of the polymer composites represents the change in polymer chain mobility in the composites directly [24]. From the glass transition parameters listed in Fig.…”