Hardness Molded Foam

Dual-Hardness Molded Foam A number of formulations for molded foams have been reported. A new development in recent years is dual-hardness molded foams. Automotive seats and furniture have been labor-intensive products. These products provide good comfort by using different layers of different hardnesses. Molded foams produced by using a single formulation have relatively comfortable cushioning properties in terms of sag factor. However, this advantage is not enough to satisfy customers requirements for comfort. 

Low-density unicellular foam made from this pressure process is available in a range of densities and hardnesses in various sizes ready for fabrication into the final product. Slab stock is used to produce shockabsorbing, flotation, and insulating foams. Typical densities range from 7 Ib/ft for shock-absorbing foams, 4 Ib/ft for flotation foams, and 6 Ib/ft for insulation foams. It is also possible to produce pressure-molded foams in cylindrical and ring-shaped molds (24) (3). 

Hard Polyurethane Foam, mainly used for insulation board is divided into two types of Foamed Products (e.g.. Spray Foam and Molded Foam). In both cases, a... 

Ultem PEI resins are amber and amorphous, with heat-distortion temperatures similar to polyethersulfone resins. Ultem resins exhibit high modulus and ate stiff yet ductile. Light transmission is low. In spite of the high use temperature, they are processible by injection mol ding, stmctural foam mol ding, or extmsion techniques at moderate pressures between 340 and 425°C. They are inherently flame retardant and generate Httie smoke dimensional stabiUties are excellent. Large flat parts such as circuit boards or hard disks for computers can be injection-molded to maintain critical dimensions. 

Unicellular foams are used for insulation, buoyancy, and flotation applications, while multicellular foams are used for upholstery, carpet backing, and laminated textiles. Expanded PS (Styrofoam), which is produced by the extrusion of PS beads containing a volatile liquid, is used to produce low-density moldings such as foamed drinking cups and insulation boards. Foamed products are also produced from PVC, LDPE, urea resins, ABS, and PU. PU foams are versatile materials, which range from hard (rigid) to soft (flexible). These are produced by the reaction of a polyol and a diisocyanate. 

Molded articles from cellular polysulfone, coated with polystyrene, epoxy resin, or vinyl resin, are reported to have improved hardness and surface rigidity. They can also be used as insulating or packaging materials, or, when modified with urea-formaldehyde resin, as flowerpots that are permeable to air and water. These foams have excellent selfextinguishing and low anoke-generating properties (21). 

Use (Rubber) Tires, hose, belting, and packing molded and extruded automotive and industrial products soles and heels hard rubber. (Latex) Adhesives, foamed rubber, textile and rug backing, paper coating and impregnation, modification of plastics to produce high-impact strength, asphalt additive. 

Polystyrene is a hard, strong, transparent solid highly resistant to mechanical impact. It is an excellent thermal (heat) and electrical insulator, is easily shaped and molded in the liquid state, and takes dyes readily. It can be produced in a wide variety of shapes and forms, including sheets, plates, rods, beads, and foams. 

About two-thirds of all the styrene produced in the United States is used in the manufacture of polystyrene. Polystyrene is a clear, colorless, hard plastic that is easily molded and made into a foam known as styrofoam. It is used in the insulation of electrical wires and devices, in containers for hot and cold foods and drinks, and for the insulation of buildings. 

Polyurethanes can have diverse properties, depending on which diisocyanate or diol is used and on whether water is excluded. Foams can be hard — like insulating material — or soft — like car seats or Miss Piggy. (Truth be told, only the early versions of Miss Piggy were made of polyurethane. As her popularity grew, she had to be mass-produced, so her makers switched to natural latex foam rubber, which they could mold readily.)... 

Many tests commonly applied to plastics in the form of solids, elastomers, coatings, and sealants may of course also be applied to cellular plastics. For example, notched impact strength tests can be applied to high-density structural foams, and it is very common to quote Shore hardness values for skin hardnesses of rigid and semirigid foam moldings. It is the intention here, however, to restrict the discussion to tests derived exclusively for plastics containing a cellular structure. 

Semirigid foam is usually tested using methods normally applied to rigid or flexible foams. In some instances they are tested for ultimate elongation (as a percentage to BS903. Part A2 [74]). The surface hardne.ss is also important in. some molded part applications, and that property can be measured using standard Shore A hardness procedures. 

Structural foam is the term usually used for foam produced in an injection molding press and made of almost many thermoplastic resin. Structural foam is always produced with a hard integral skin on the outer surfaces and a cellular core in the interior, and is used almost exclusively for production of molded parts. The process is thus ideally suited for fabrication of parts such as business machine housings (commonly for ABS), and similar parts or components in which lightweight and stiffness are required. 

Chem. Descrip. Calcium carbonate CAS 471-34-1 EINECS/ELINCS 207-439-9 Uses Filler/extender used in interior flat paint and exterior house paints, rubber compds. (NR, SR), polyvinyl plastisols, PE and polyester resins, putty and caulk, ceramics, adhesives, linoleum, floor tile, aril textile coatings filler in heels, soles, flooring, mats, molded and extruded goods, foam prods., footwear, sundries, SMC Properties Wh. powd. 7.0 avg. particle diam. 99.5% finer than 44 50.0% finer than 7 0.03% sol. in water sp.gr. 2.70-2.71 dens. 22.57 Ib/gal solid bulk dens. 58 Ib/ff (loose) oil absorp. 13 cc/100 g brightness (Hunter) 93 ref. index 1.6 pH 9.5 (sat.) hardness (Mohs) 3.0 Toxicology Nontoxic Camel-FINE [IMERYS]... 

Uses Mold release coatings used when molding rigid and flexible PU foam and PU elastomer parts from metal and RTV molds provides hard, flexible surf, coating with exc. adhesion props. can be mfg. in customized colors... 

Chem. Descrip. Calcium carbonate (99.7%) coated by stearine acid CAS 471-34-1 EINECS/ELINCS 207-439-9 Uses Filler for paints (primers, undercoats), plastics (PVC rigid extrusion, PVC foam extmsion, PVC calendered sheet, PVC inj. molding), rubber, adhesives, sealing compds., and fire extinguishers Properties Spherical crystals 30% < 2 p sp.gr. 2.7 bulk dens. 1.1 g/ml (packed) surf, area 3.5 m /g oil absorp. 14/100 g dry brightness 93% pH 9 ref. index 1.58 hardness (Mohs) 3 < 0.2% moisture MT Binder ENB 02 [Bayer AG]... 

Acrylonitrile is also incorporated into Buna N and ABS polymers. Polymers from acrylonitrile, acrylamide, and acrylic acid can be blow-molded using y- or -irradiation in the molds. The resulting hard foams, which can be used as heat insulators up to 150°C, are comparable in price to polyurethanes. 

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