Closed microcellular

Williams, J. Wrobleski, D.A. Spatial distribution of the phases in water-in-oil emulsions open and closed microcellular foams from cross-linked polystyrene. Langmuir, 1988, 4, 656-662. 

One physical foaming process involving glassy poly(ether imide)s and poly(ether sulfone)s using CO2 has been investigated. Two types of porosities were observed, closed microcellular and bicontinuous. In this work, the foaming behaviors of thin (-TSftM) extruded poly(ether Itnide) (PEI) and poly(ether sulfone) (PES) films were studied (Table I). 

Olefins or alkenes are defined as unsaturated aliphatic hydrocarbons. Ethylene and propylene are the main monomers for polyolefin foams, but dienes such as polyisoprene should also be included. The copolymers of ethylene and propylene (PP) will be included, but not polyvinyl chloride (PVC), which is usually treated as a separate polymer class. The majority of these foams have densities <100 kg m, and their microstructure consists of closed, polygonal cells with thin faces (Figure la). The review will not consider structural foam injection mouldings of PP, which have solid skins and cores of density in the range 400 to 700 kg m, and have distinct production methods and properties (456). The microstructure of these foams consists of isolated gas bubbles, often elongated by the flow of thermoplastic. However, elastomeric and microcellular foams of relative density in the range 0.3 to 0.5, which also have isolated spherical bubbles (Figure lb), will be included. The relative density of a foam is defined as the foam density divided by the polymer density. It is the inverse of the expansion ratio . 

Journal of Applied Polymer Science 83, No.2, 10th Jan.2002, p.357-66 MORPHOLOGY AND PHYSICAL PROPERTIES OF CLOSED CELL MICROCELLULAR ETHYLENE-OCTENE COPOLYMER EFFECT OF PRECIPITATED SILICA FILLER AND BLOWING AGENT Nayak N C Tripathy D K Indian Institute of Technology... 

An investigation is reported of the dynamic mechanical response of aluminium silicate filled closed cell microcellular ethylene-octene copolymer (Engage) vulcanisates. The effect of blowing agent, frequency and temperature on dynamic mechanical properties is studied, and the strain-dependent dynamic mechanical properties of microcellular Engage are also investigated. 25 refs. INDIA... 

Plasticization of glassy polymers induced by CO2 plays an important role in the process of foaming of glassy polymers. The preparation of polymeric foams is aimed at the production of microcellular polymers that have closed cells about 10 pm or less in diameter and cell density of about 10 cells/cm. Such foamed polymeric materials have applications in many areas including biomedical devices. Pioneering work by Skripov and coworkers (54,55) stimulated the original interest in this field. 

Uses Polyol for PU coatings, adhesives, elastomers, microcellular, TPU Properties Vise. 4000 cps hyd. no. 54-58 Storage Hygroscopic store in tightly closed containers Fomrez E65-56 [Uniroyai]... 

Microcellular polymers produced by gas nucleation, refer to closed cell thermoplastic foams with a very large number of very small cells (of the order of 10 mm in diameter), typically 10 or more cells per cm. Microcellular thermoplastics have been obtained from a number of different polymers, ranging in relative density from 0.1 to 1.0 kg/m, containing 10 to 10 cells per cm, offering a new range of properties for design [6, 7]. For example microcellular PU foams can be obtained via polymerisation in carbon dioxide [8, 9]. 

Microcellular polymers are closed cell thermoplastics produced by gas nucleation. They have a high number of very small cells with a diameter of 10 pm, and bubble densities in excess of 100 million per cm. First produced in the early 1980s with the objective of reducing the amount of polymer used in mass produced items, these novel materials have the potential to revolutionise the way thermoplastic polymers are used today. PVC, PS, polycarbonate (PC), polyethylene terephthalate (PET) and not only these polymers can be applied for such kinds of products. As no harmful chemicals are used in the microcellular technology, it is likely that these new products will replace many types of foam now produced by processes that damage the environment [59]. 

Microcellular plastics (MCPs), which were first invented at the Massachusetts Institute of Technology in 1979, refer to any polymeric materials that have closed cells of very small diameters, typically smaller than 50 /rm. The cell density can be made to vary a great deal depending on the final application of a given MCP. MCPs can have as many as 10 bubbles/cm when the bubble diameter is 0.1 /rm, 10 bubbles/cm for 1-p.- and 10 for 10-/r- diameter cells. They can be created in thermoplastics, thermosetting plastics, and elastomers. Figure 1 shows the microstructin-e of a typical MCP. See Reference 1 for a detailed historical account as well as a detailed review of MCPs. 

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