Microcellular flexible foams

Semi-flexible foams (or semi-rigid foams) are sometimes classified as subdivisions of flexible foam because the foams have higher load-bearing properties and good compression recovery. Microcellular flexible foams and integral-skin flexible foams may also be classified in this category. In some classifications, however, microcellular foams are classified as elastomers. 

Pure MDI, having two -NCO groups/mol, is commercialised mainly as 4,4" isomers, but it is possible to use 2,4 and 2,2 isomers. The main applications of pure MDI (especially the 4,4" isomer) are polyurethane elastomers, microcellular elastomers and some flexible foams. The structures of pure MDI isomers are presented in Figure 2.2. 

AA-TMP/glycols (branched) Flexible foams, microcellular elastomers, coatings... 

TDI/Polyester Slabstock Flexible Foams TDI/Polyester Slabstock Flexible Foams TDI/Polyester Slabstock Flexible Foams MDI or NDI Microcellular Foam MDI or NDI Microcellular Foam Rigid Foam... 

Injected parts transparent, filled to a greater or lesser degree, possibly crosslinked and/or foamed in microcellular form for tyres (light uses), kneepads, footwear, soles, sports and technical items, buoys, flexible toys, protective caps. .. 

By crosslinking, the viscosity of EVA at high temperatures is increased and the individual cells are kept in a stable condition without rupture or agglomeration. A low density microcellular foam can be thus obtained. By selecting the vinyl acetate content, the EVA foam is flexible and highly resilient with easy coloring and adherent to other materials. The application is used widely in shoe soles, sandals and cushion materials. 

This book describes the chemistry, manufacture and use of the wide range of flexible polyurethane foams, from low-density open-cell upholstery foams to microcellular and reaction- injection-molded and reinforeed-reaction-injection-molded materials. The related effects of varying the raw-material chemistry and the production process and machinery on the properties and service performance of the final product are indicated. 

ASTM D 1565, a specification, outlines a test method for dynamic flexing of flexible vinyl cellular materials. This test uses a flexing machine which oscillates at 1 Hz. A minimum of 250,000 flexes are applied. After alternate compression and relaxation the effect on the structure and thickness of the foam is observed. The percentage loss of thickness is reported. Flexural modulus of microcellular urethane is described in ASTM D 3489. This method uses the general procedure in ASTM D 790, Method I. ASTM D 3768 outlines a procedure for determining flexural recovery of microcellular urethanes. The method is used to indicate the ability of a material to recover after a 180° bend around a 12.7-mm (0.5 in.) diameter mandrel at room temperature. 

Quasiprepolymers are frequently used to transform a solid isocyanate, (e.g., pure MDI), into a liquid, and are used in flexible PU foams, in microcellular elastomers and in other PU applications. 

Applications cold moulded high resilience flexible PU foams, semiflexible and integral skin PU foams, microcellular elastomers (shoe soles) ... 

Reasons for use improve compatibility with other additives and polymers, improve flame resistance, improve low temperature performance, increase chain mobility, increase filler loading, increase flexibility and elongation, inflnence blood compatibility, lower glass transition temperature, lower viscosity, lower processing, gelation and fusion temperatures, modify foaming rate and microcellular stractirre... 

Uses PU intermediate for flexible, water-resist, fabric coatings, microcellular foams which are resist, to HC soivs., polyether-based molded foam formulations to improve adhesion between the foam and vinyl mold skins Features Polyester polyol... 

Uses Colorant for flexible, rigid, and seml-rigid foams, RIM, high dens, molded foams, and microcellular urethanes, castings, films, and coatings... 

The major applications for polyurethane catalysts are in flexible and rigid foam, which account for over 80% of the catalyst consumption. Other applications are in microcellular reaction injection-molded (RIM) urethanes for automobile bumpers and a variety of noncellular end uses such as solid elastomers, coatings, and adhesives. 

Control of the reaction sequence in making flexible, open-cell, polyurethane foam using the one-shot process is accomplished by choosing the polyol, the surfactant, and the combination of tertiary-amine and organometallic, usually tin, catalysts. As in the previously described procedures for making urethane elastomers and microcellular products, for foams, polyols— poly(propylene oxide) polyols often containing minor amounts of ethylene oxide—are used. These polyols are selected by functionality, molecular weight, and reactivity (see Table 3). 

Pegospers 400 MS surfactant, silicone flexible PU Struksilon 8104 Stnikslon 8120 Stniksilon 8182 Stnikslon 8183 surfactant, silicone microcellular foams... 

Flexible, flexible molded, and microcellular foams Automotive seating and furniture Flexible and rigid foam Insulation/structural panels... 

Rigid, flexible/slabstock foam, microcellular plastomers,and integral skin foam Rigid, flexible, integral skin, flexible molded,microcellular foam, coatings, and elastomers... 

Flexible slabstock foam Elastomers and coatings Microcellular foam Shoe soles Microcellular foam Shoe sole market... 

RC Crosslinker B Flexible, Integral Skin, Microcellular Foam, Polyesters,Coatings, Elastomers, and TPU... 

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