Flexible molding

Another type of polyol often used in the manufacture of flexible polyurethane foams contains a dispersed soHd phase of organic chemical particles (234—236). The continuous phase is one of the polyols described above for either slab or molded foam as required. The dispersed phase reacts in the polyol using an addition reaction with styrene and acrylonitrile monomers in one type or a coupling reaction with an amine such as hydrazine and isocyanate in another. The soHds content ranges from about 21% with either system to nearly 40% in the styrene—acrylonitrile system. The dispersed soHds confer increased load bearing and in the case of flexible molded foams also act as a ceU opener. 

Silicone They have excellent heat resistance up to 260°C (500°F), chemical resistance, good electricals, compatible with human body tissues, etc. and a high cost. There are the room temperature vulcanizing (RTV) types that cure and cross-link at ambient temperatures, catalyzed by moisture in the air. It is a good sealant and excellent for making flexible molds for casting. It is widely used for human implants. 

Refs 1) Anon, Nylon Plastic, Flexible, Molded Or Extruded , MIL-N-18352 (1955) 2) Kirk... 

The die-and-punch method of compact imparts an anisotropic pressure to the compact. It is possible to apply pressure equally in all directions using a process called isostatic pressing, in which the powder is compacted with a fluid, such as hydraulic fluid, water, or an inert gas. Isostatic pressing is carried out using formed, flexible molds, called cans, that contain the powder and allow the pressure from the fluid to be transferred to the powder. The flexible molds are then stripped off the compact after densification. Isostatic pressing eliminates the die-wall friction inherent in die compaction and allows for consolidation of large components. However, isostatic pressing... 

Isostatic molding — PTFE molding technique allowing uniform compression from all directions. It uses a flexible mold, which is filled with free-flowing granular powder. It is used for parts with complicated shapes. 

Isostatic compaction Powder encased in flexible mold is pressed equally from all directions by pressure transmitted to the mold by a liquid medium. Isostatic molding, isostatic pressing Hydrostatic molding chambers, automatic isostatic presses... 

Recently, delayed-action catalysts have been used to adjust reactivity profiles for rigid and flexible molded foams (38). Some of these catalysts are shown in Table 10. 

Use Sealing, caulking, encapsulating and flexible mold-making in electronic, aircraft, missile and building industries. 

McClelland, G.M. Hart, M.W. Rettner, C.T. Best, M.E. Carter, K.R. Terris, B.D. Nanoscale patterning of magnetic islands by imprint lithography using a flexible mold. Appl. Phys. Lett. 2002, 81 (8), 1483-1485. 

MAJOR PRODUCT APPLICATIONS carpet underlay, shoe soles, roof sealant, roller, wheelchair tire, industrial coating, construction panel, industrial enclosures, foam boot-insert, automotive components, marine equipment, slip-resistant coatings, deck coatings, flexible mold, in-line skate wheels... 

Cold Isostatic Pressing. In isostatic pressing, the powder is filled into flexible molds made of rubber or elastomers and subjected to hydrostatic pressure. The pressure is commonly in the range of 200 to 400 MPa. As a result of the uniform pressure, a much higher uniformity in density is achieved. Isostatic pressing has gained much... 

In the dry bag process, the flexible container is fixed in the pressure vessel and the powder is loaded directly. The tool forms a membrane between the fluid and the powder. Optionally, the flexible container may be placed inside of a primary diaphragm so that the powder never comes in contact with the fluid, even if the flexible mold is damaged or breaks. Therefore, dry bag tooling also has the advantage that the fluid is not contaminated with the powder. However, because the container must stand up to many pressing cycles and since changing it is time consuming, it has to be made of a very durable material. 

The liquid polymers have the additional advantage of ease of application. They can be converted with little shrinkage from a solvent-free liquid to a firm rubber even at room temperature. They can be utilized in many applications where conventional rubbers could not be applied. These uses include (1) impregnation of leather for many mechanical uses, (2) cast rollers for printing, (3) sealing compounds or fuel tanks, (4) calking compounds for concrete, metal, and wood, (5) flexible molds, (6) potting com pounds, and (7) adhesives. 

Polyvinyl acetals are used as insulators for wire coatings, for the impregr nation of paper and fabrics, for the production of flexible molded and extruded articles, and as interlayers in safety glass. In the last application, they are superior to any other material thus far tried. 

Used when oil resistance, good weathering, and inflammability characteristics are needed Gaskets, door seals, medical application flexible molds... 

Polytek Development, USA Flexible mold materials and rigid castings resins for composites, incl. silicone and urethane mold components... 

Uses Gelation catalyst for rigid, flexible, and semi-flexible molded slabstock, coatings, sealants, elastomers, and shoe soles Features Very strong with delayed action Properties Insol. in water sp.gr. 1.18 vise. 400 mPa-s flash pt. (PMCC) 85 C... 

Chem. Descrip. Proprietary blend ot delayed-activity tin and a tert. amine Uses Gelation catalyst tor flexible molded and rigid PU, PU coatings, elastomers, shoe soles Features Delayed-action... 

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