High performance nanocomposites of polyurethane elastomer and organically modified layered silicate

Abstract

High performance nanocomposites comprising a polyurethane elastomer (PUE) and an organically modified layered silicate are prepared. These nanocomposites are based on poly(propylene glycol), 4,4Ј-methylene bis(cyclohexyl isocyanate), 1,4-butandiol, and organoclay. The tensile strength and strain at break for these novel PUE nanocomposites increases more than 150%, but the hardness remains unchanged. The fatigue properties are significantly improved. With 3 wt % organoclay, the fatigue properties are improved the most, which is important for the PU industry. The effects of the isocyanate index on the mechanical properties of the PUE nanocomposites are investigated. It is found that an isoyanate index of 1.10 results in the best improvement in stress and elongation at break.

Molecular Dynamics Simulation of the Fracture in Polymer‐Exfoliated Layered Silicate Nanocomposites

“…Such a phenomenon has been experimentally observed in polyurethaneorganoclay nanocomposites. [12] However, there is a linear relationship between W Ã and the content of the nanoplatelets below the T g of the polymer. It can be found that the contribution of the nanoplatelets to the enhancement of the fracture strength of the polymer below its T g is less than at above its T g .…”

“…A typical example are epoxy-organoclay nanocomposites. [15] Series research results [1,7,10,12] indicate that the addition of clay into those polymers with T g below or close to room temperature has significant enhancement on the mechanical properties. Tensile properties and fatigue durability of polyurethane, the T g of which is about À40 8C, were intensively enhanced by the incorporation of organoclay.…”

“…Epoxy-organoclay, nylon-organoclay and polyurethane-organoclay nanocomposites have been investigated for about 10 years. [1] The addition of organoclay always enhanced the mechanical properties of polyurethane [7,12] and also can improve the mechanical properties for nylons. However, the addition of organoclay does not result in an enhancement of the toughness of epoxy resins.…”

“…A polymer chain consisting of 64 hard beads connecting with spring was used in this simulation. Beads of mass m were separated by a distance r. The interaction between beads (or between nanofillers) was described by a Lennard-Jones potential, V LJ , and the potential is zero for r > cut-off radius, r c V LJ ðrÞ ¼ 4e½ðs=rÞ 12 À ðs=rÞ…”

“…Intercalated clay nanocomposite show an improvement of fatigue durability, and elongation at break. [12] Exfoliated clay nanocomposites improve barrier properties [13] and moduli. [14] The addition of clay into polymers with glass transition temperatures (T g ) below or about equal to room temperature, significantly enhances the mechanical properties of these polymers.…”