Molded elastomer

Many of the molded elastomer liners are interchangeable with... 

Davies model (see Equation 20.3 [20,21]) can be used for materials with co-continuous interpenetrating phases (as in interpenetrating networks), such as certain types of reaction injection molded elastomers [22], at all volume fractions. Equation 11.7 can then be used if (as is usually the case) one is interested in Young s modulus E rather than the shear modulus G. 

Compression Preferred with duroplastics and molding elastomers with thermoplastic... 

Chem. Descrip. Dibutyltin diacetate CAS 1067-33-0 EINECS/ELINCS 213-928-8 Uses Gelation catalyst for PU coatings, flexible molds, elastomers, shoe soles... 

Uses For PU industry for molded elastomers, industrial/consumer RIM and structural polymers, e.g., air conditioning covers, agric. equipment, also for adhesives, binders, coatings, and sealants industries and for appliances and rigid foams... 

Uses For polyurethane industry for adhesives, binders, coatings, and sealants, molded elastomers, stmcturalfoam molding, appliances prod, of polyhydantoin resins, urethane-acrylate resins Trade Names Papi901... 

In most cases the cycle also repeats itself automatically. Only imder certain conditions or for special molded parts may it be necessary for the machine to stop at the end of a cycle. After manual intervention by the machine operator, the machine is prepared for the next eycle and then restarted. This is done with molded elastomer parts, for example, whieh generally must be removed by hand. 

Polytetramethylene ether glycol PU, industrial belts Polytetramethylene ether glycol PU, medical devices Polytetramethylene ether glycol PU, molded elastomers Polymeric MDI PU, pipe liners... 

Fig. 12 Fabrication of molded elastomer composites with coagulated latex matrix.

Fig. 13 Molded elastomer composite produced with coagulated latex matrix, seen from top (left) and below (right).

Modern IM processes offer the user numerous, almost confusing settings. Process windows are searched for different times, velocities, pressures, temperatures, forces and paths for the individual phases with respect to their dependencies for each product, the mold used, and the used elastomer mixture. The goal is to produce a product as economically and qualitatively robust as possible. The time required to find optimum process windows is, in spite of technical assistance (e.g., by so-called cure time calculators), still dependent on the experience of the particular user or process engineer and the quality of the resources used (mold, elastomer, machine). 

B672X01—special/for blow molding (elastomer alloy) — 0.20 980... 

Casting resin Thermoplastic elastomer Cast resin, flexible Mineral- and/or glass-filled Epoxy molding and encapsulating compound Polystyrene... 

HDPE, high density polyethylene PP, polypropylene EVA, ethylene—vinyl alcohol SMC, sheet-molding compound ERP, fiber-reinforced plastic LDPE, low density polyethylene PE, polyethylene BMC, bulk mol ding compound TPE, thermoplastic elastomer. 

Latex mbber foams are generally prepared in slab or molded forms in the density range 64—128 kg/m (4—8 lbs/fT). Synthetic SBR latexes have replaced natural mbber latexes as the largest volume raw material for latex foam mbber. Other elastomers used in significant quantities are polychloroprene, nitrile mbbers, and synthetic i j -polyisoprene (115). 

The use of TAG as a curing agent continues to grow for polyolefins and olefin copolymer plastics and mbbers. Examples include polyethylene (109), chlorosulfonated polyethylene (110), polypropylene (111), ethylene—vinyl acetate (112), ethylene—propylene copolymer (113), acrylonitrile copolymers (114), and methylstyrene polymers (115). In ethylene—propylene copolymer mbber compositions. TAG has been used for injection molding of fenders (116). Unsaturated elastomers, such as EPDM, cross link with TAG by hydrogen abstraction and addition to double bonds in the presence of peroxyketal catalysts (117) (see Elastol rs, synthetic). 

Diamine curatives were the first cross-linking agents for fluorocarbon mbbers. They are corrosive to mild steel molds and have been replaced in many appHcations by the bisphenol or other more recent cure systems. Nevertheless, some diamines are stiU used for food-contact appHcations of fluorocarbon mbbers and in zinc-free cures of halobutyl mbbers for pharmaceutical stoppers. Methylene dianiline and triethylene tetramine are cross-linking agents for ethylene—acryflc elastomers. 

Urethanes are processed as mbber-like elastomers, cast systems, or thermoplastic elastomers. The elastomer form is mixed and processed on conventional mbber mills and internal mixers, and can be compression, transfer, or injection molded. The Hquid prepolymers are cast using automatic metered casting machines, and the thermoplastic peUets are processed like aU thermoplastic materials on traditional plastic equipment. The unique property of the urethanes is ultrahigh abrasion resistance in moderately high Shore A (75—95) durometers. In addition, tear, tensUe, and resistance to many oUs is very high. The main deficiencies of the urethanes are their resistance to heat over 100°C and that shear and sliding abrasion tend to make the polymers soft and gummy. 

The Hquid monomers are suitable for bulk polymerization processes. The reaction can be conducted in a mold (casting, reaction injection mol ding), continuously on a conveyor (block and panel foam production), or in an extmder (thermoplastic polyurethane elastomers and engineering thermoplastics). Also, spraying of the monomers onto the surface of suitable substrates provides insulation barriers or cross-linked coatings. 

The largest segment of the CASE family of polyurethanes are elastomers. Cast polyurethane elastomers reached a new dimension when high pressure impingement mixing led to reaction injection molding (RIM). This technology is used widely in the automotive industry, and reinforced versions (RRIM) and stmctural molded parts (SRIM) have been added in more recent years. 

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