Morphology and properties of thermoplastic polyurethane composites incorporating hydrophobic layered silicates

Abstract

Polyurethane (PU) composites incorporating Cloisite 15A (15A) were prepared via melt compounding and solvent casting. The melt-compounded composites had better dispersion and a smaller silicate stack size as a result of the higher shear forces associated with twin-screw extrusion. The PU microphase separation and hard domain order were greater in the melt-processed materials. At the concentrations of 15A employed in this study (Յ7 wt %), the filler did not have an observable effect on the microphase texture of either the solvent-or melt-processed PU. The tensile properties of the melt-compounded materials were lower than those of their solvent-cast counterparts because of thermal degradation. The solvent-cast composite containing a 3 wt % loading of 15A displayed improved tensile strength and elongation, primarily because of plasticization by the silicate organic treatment. The addition of layered silicates with high aspect ratios increased the hysteresis and permanent set of this PU elastomer.

Evaluating the effect of processing conditions and organoclay content on the properties of styrene-butadiene rubber/organoclay nanocomposites by response surface methodology

“…It is well known that the elongation at break of rubber nanocomposite depends on the morphology of nanocomposites. Due to slippage of rubber chains in the presence of the free surfactant of nanoclay in exfoliated or intercalated morphology, the elongation at break increases [25][26][27][28][29]. In other words, the surfactant can act as a lubricant in the nanocomposites.…”

Fluoromica nanoparticle cytotoxicity in macrophages decreases with size and extent of uptake

“…The nanofiller can enhance the mechanical properties of the composite by direct interaction with the polymer chains. 30,31 Moreover, these composites have been studied as potential components in medical implants, and as drug delivery systems. 32,33 Consequently, as part of their safety evaluation, human exposure to fluoromica nanoparticles requires an understanding of their potential biological interactions and adverse effects.…”

Organization of mixed dimethyldioctadecylammonium and choline modifiers on the surface of synthetic hectorite

“…Organoclays which are modified with a single type of surfactant can preferentially associate with one of the segments, which can detrimentally disrupt the underlying morphology [10][11][12]. In many cases, the enhancement in properties is accompanied with a loss of resilience and an increase in stiffness and sometimes brittleness [8][9][10]13,14], which in turn limits the number of potential applications.…”

“…A challenge therefore arises when the polymers consist of segments with differing polarity, such as in block co-polymers and segmented polyurethanes. Prior, the literature shows that the chemical structure of surfactants determines the degree of organoclay exfoliation, distribution, and mechanical properties of polyurethane nanocomposites [8,9]. Organoclays which are modified with a single type of surfactant can preferentially associate with one of the segments, which can detrimentally disrupt the underlying morphology [10][11][12].…”