Polyurethane montmorillonite

Xiong J, Liu Y, Yang X, Wang X. Thermal and mechanical properties of polyurethane/ montmorillonite nanocomposites based on a novel reactive modifier. Polym Degrad Stab December 2004 86(3) 549-55. 

Keywords polyoxymethylene, polyurethane, montmorillonite, nanocomposite, mechanical properties, thermal degradation. 

It has been found that the interaction of intercalated and/or exfoliated nanoparticles may restrict the mobility of the matrix polymer chains, which lead to an increase of Tg values, as observed in nanocomposites of polyamide-12-layered silicates [102], nitrile rubber-organophilic montmorillonite [103], natural rubber-montmorillonite [104], and EVA-day [105]. A slight increase with the organosurface treatment in Tg values was noticed in poly(vinyl chloride)-clay [106,107], poly(vinyl chloride)-CNTs [108], polyurethane-montmorillonite [109-111], LLDPE-layered tetrasilisic fluoromica [112], PP-montmorillonite [113-115], PP-sUica [116], and styrene-butadiene rubber [117]. 

The best-performing composite was prepared with H30 at 8 wt. % montmorillonite. The ratio 1.83 indicated the largest enhancement of modulus relative to the pure polyurethane for the 8 wt.% containing composites. The percent elongation to failure increased from 236 15% for the pure polymer to 374 32% for the 8% loaded polyurethane-montmorillonite composite. These hyperbranched polyols provide a significant enhancement of mechanical properties for the polyurethane cure chemistry evaluated with Cloisite 30B as the dispersed-phase reinforcement. Additional work needs to be done with Cloisite 30B present during the cure to ascertain if further benefits to mechanical properties are derived from the reaction of the isocyanate with the primary hydroxyls on the quat exchanged onto the montmorillonite. 

The advent of polyurethane-montmorillonite nanocomposites presents the unique opportunity to integrate two phases (soft continuous phase with a harder dispersed phase) with a montmorillonite-dispersed nanoparticle. The opportunity to provide functionality that will cure with the urethane on the surface of the montmorillonite results in a unique composite with mechanical properties that is not duplicated by other polymer-montmorillonite nanocomposites. 

Moon S-Y, Kim J-K, Nah C and Lee Y-S (2004) Polyurethane/montmorillonite nanocomposites prepared from crystalline polyols, using 1,4-butanediol and organoclay hybrid as chain extender, Eur Polym J 40 1615-1621. 

The glass fibre, PPG 3540, is a polyurethane-sized glass fibre manufactured by PPG Industries, Inc. The surface treatment on the glass fibre promotes good adhesion between the fibre and the polymer. b Note montmorillonite is surface treated with octadecylammonium or dioctadecyldimethylammo-nium ions. 

Nanoparticles are now being investigated and used to provide some extra stiffness to polyurethanes. These are very small, flat, claylike platelets of micron size. Montmorillonites of size 2 to 13 microns have been used. They can have functional groups such as amine attached to them. The particles have to be fully defoliated and wetted by the polyurethane. The functional groups will bond to the hard segments. 

The synthesis of dimeric fatty acids is based on the reaction between a fatty acid with one double bond (oleic acid) and a fatty acid with two double bonds (linoleic acid) or three double bonds (linolenic acid), at higher temperatures in the presence of solid acidic catalysts (for example montmorillonite acidic treated clays). Dimerised fatty acids (C36) and trimerised fatty acids (C54) are formed. The dimer acid is separated from the trimeric acid by high vacuum distillation. By using fatty dimeric acids and dimeric alcohols in the synthesis of polyesters and of polyester polyurethanes, products are obtained with an exceptional resistance to hydrolysis, noncrystalline polymers with a very flexible structure and an excellent resistance to heat and oxygen (Chapter 12.5). Utilisation of hydrophobic dicarboxylic acids, such as sebacic acid and azelaic acid in polyesterification reactions leads to hydrolysis resistant polyurethanes. 

Similar to all other auxiliaries, thickeners influence the water retention and open time, water resistance, washfastness, abrasion resistance, weather resistance, and gloss. The most important thickeners are methyl cellulose and hydroxyethyl cellulose. The viscosity rises with increasing polymerization of the cellulose ether. Synthetic thickeners based on poly(meth)acrylates, polyvinylpyrrolidone, and polyurethanes are also important. Inorganic thickeners include layer silicates of the montmorillonite type (e.g., aluminum silicate and magnesium silicate). They confer a better washfastness and abrasion resistance than the cellulose ethers and polyacrylates. However, they develop a lower water retention capacity (open time). 

Polyurethane/clay-based nanocomposites are already being used for automobile seats and it also exhibit superior flame retardancy. Phenolic resin impregnated with montmorillonite clay was already identified as the resin for manufacturing rocket ablative material with MMT. The nanolevel dispersion of clay platelets leads to a uniform char layer that enhances the ablative performance. The formation of this char was slightly influenced by the type of organic modification on the silicate surface of specific interactions between the polymer and the silicate platelets surface, such as... 

Hong JH, Jeong EH, Lee HS, Baik DH, Seo SW, Youk JH (2005) Electrospinning of polyurethane/organically modified montmorillonite nanocomposites. J Polym Sci B Polym Phys 43 3171-3177... 

S. Semenzato, A. Lorenzetti, M. Modesti, E. Ugel, D. Hrelja, S. Besco, R. A. Michelin, A. Sassi, G. Facchin, F. Zorzi, and R. Bertani, A novel phosphorus polyurethane FOAM/montmorillonite nanocomposite Preparation, characterization and thermal behaviour. Applied Clay Science, 44 (2009), 35 2. 

Additives used in final products Fillers barium and strontium ferrites, boron carbide, calcinated clays, calcium carbonate, carbon black, carbon-silica dual phase filler, clays, dolomite, fumed silica, iron oxide, magnesium aluminum silicate, magnesium carbonate, mica, montmorillonite, nickel zinc ferrite, nylon fibers, pulverized polyurethane foam, quartz, silica carbide, soapstone, talc, zinc oxide Plasticizers naphthenic oil, polybutene, aromatic oil, esters of dicarboxylic acid Plasticizers adipates, aromatic mineral oil, paraffin oil, phosphates, phthalates, polyethylene glycol, processing oil, sebacates Antistatics dIhydrogen phosphate of 8-amlnocaprolc add. Iodine doping Antistatics carbon black, quaternary ammonium salt, zinc oxide whisker Antiblocking diatomaceous earth Release propylene wax Slip erucamide+stearamide ... 

Tortora, M. Gorrasi, G. Vittoiia, V. GaUi, G. Ritrovati, S. ChieUini, E. Structural characterization and transport properties of organically modified montmorillonite/ polyurethane nanocomposites. Polymer IWl, 43, 6147-6157. 

Strankowskl M, Strankowska J, Gazda M, Piszczyk L, Nowaczyk G, Jurga S (2012) Thermoplastic polyurethane/(organically modified montmorillonite) nanocomposites produced by in situ polymerization. Exp Polym Lett 6(8) 610-619... 

Ni P, Li J, Suo J S and Li S B (2004) Novel polyether polyurethane/clay nanocomposites synthesized with organic-modified montmorillonite as chain extenders, J Appl Polym Sci 94 534-541. 

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