Elastomers types

Special Types. Many other coupling types are available. These vary ia degree of complexity, maintenance time, torque capabiUties, and price. A good comparison study on coupling is available (36). An elastomer-type coupling is one of the most popular types used, particularly ia the chemical iadustry. 

Table 4. Worldwide Long-Term New Rubber Consumption by Elastomer Type, 10 t...

Compatibility and Corrosion. Gas turbine fuels must be compatible with the elastomeric materials and metals used in fuel systems. Elastomers are used for O-rings, seals, and hoses as well as pump parts and tank coatings. Polymers tend to swell and to improve their sealing abiUty when in contact with aromatics, but degree of swell is a function of both elastomer-type and aromatic molecular weight. Rubbers can also be attacked by peroxides that form in fuels that are not properly inhibited (see Elastomers, synthetic Rubber, natural). 

The excellent low temperature properties of FZ have been iadicated ia Table 1. Modulus curves were obtained usiag dynamic mechanical spectroscopy to compare several elastomer types at a constant 75 durometer hardness. These curves iadicate the low temperature flexibiUty of FZ is similar to fluorosihcone and ia great contrast to that of a fluorocarbon elastomer (vinyUdene fluoride copolymer) (Fig. 3) (15). 

Figure 3 Percent unfills by elastomer type for 5-s mold closure.

Figure 6 Percent excess flash by elastomer type for 11-s mold closure.

Elastomer types used successfully in these areas are natural rubber (NR), polychloroprene (CR), and nitrile rubber (NBR), and hydrogenated nitrile rubber (HNBR), where oil resistance is also required. 

Values from high-pressure permeation tests can give useful information regarding the selecting of elastomer types to withstand potential explosive (rapid gas) decompression damage (Sections... 

An elastomeric closure is a packaging component that is, or may be, in direct contact with a drug product. Elastomer selection for parenteral packaging principally involves consideration of chemical, physical, and biological properties, with emphasis on the stability profile of the drug/container system. Typical elastomeric closure compositions are listed in Tables 1 1. Although certain packaging applications frequently call to mind certain elastomer types, it is not feasible to prescribe specific... 

Diffusion of a gas or liquid through a semi-permeable material. The permeability of elastomers to gases varies with the elastomer type and with the gas. Butyl rubber is much less permeable to air than is natural rubber hence its use in tyre inner tubes and similar apphcations. The rate of permeation is generally related to the size of gas molecule, i.e., the smaller the molecule the higher the rate. The exception is C02 which has a rate 10 to 100 times greater than that of nitrogen. 

Types 1, 2, and 3 were selected for test with each of the primers, types A, B, and C. In addition, type 4 elastomer was used as a primer for types 1, 2, and 3. All elastomers types 1-6 were also tested without primers. 

All samples primed with type B primer showed visible corrosion at a very early date. Within one week of water submersion, all of these samples showed some signs of deterioration. In each case, the side of the pattern maintained at positive potential was the first to discolor and then corrode. In contrast none of the samples primed with type 4 material showed visible deterioration at day 60. With the exception of the type B samples, all of the other samples failed to show any noticable deterioration until one month into the test. At this time, most of the types A, B, and C primed samples showed discoloration and debonding. Correspondingly their leakage currents, at day 30, were an average of 35 times greater than those samples primed and encapsulated with the self-priming elastomer types 4, 5, and 6. 

Solvent absorption measurement has been shown to be a sensitive and useful test method in the manufacture of epoxy powder coatings. A test method was defined and the effects of time and temperature of immersion described. It was shown that solvent absorption is a measure of raw material properties (EEW of the epoxy resin, and CTBN elastomer type and concentration), the homogeneity of the extrudate, as well as the state of cure. The information obtained from solvent absorption measurements has proven to be extremely important not only in quality control analysis but also in providing an insight into the structure function relationships in epoxy resin chemistry. 

Grade name Elastomer type Matrix phase Supplier... 

Elastomer Types According to American Society of Testing Materials-ASTM D2000... 

Plasthall [Hall]. TM for a broad range of monomeric and polymeric plasticizers used in polymers and elastomers. Types include adipates, gluta-rates, trimellitates, azelates, sebacates, and tallates. 

In common with the mineral-based H-515 fluid the PAO-based fluids also contain hindered phenol-based anti-oxidants and TCP as an anti-wear agent but, as previously stated, they do not need the addition of a VI improver [27]. PAOs tend to give very low swell of the elastomer types used in the applicable hydraulic systems. A certain degree of elastomer swell is required to ensure good sealing of the system and therefore the PAO-based fluids contain up to 35% by weight of di-ester to produce sufficient seal swell. 

The liquid crystalline polymer has since developed far beyond imagination that a decade ago. The liquid crystalline polymer family has so far included the main chain-, side chain-, and crosslinked- (i.e. network or elastomer) types, and their solutions and gels. The liquid crystal phases cover nematic, cholesteric and smectics. Although the science of the liquid crystalline polymer is not fully mature, it has attracted significant research interests and has already made tremendous progress. As investments and human resources continue, the liquid crystalline polymer is expected to have an even brighter future. 

Figure 6. Simulated variation of the ratio rubber phase volume/styrene + polystyrene phase volume vs. styrene conversion EPDM elastomer, type C and polystyrene, [tj] toluene/30°C = 0.8 dl/g...

EPDM elastomer, type C and elastomer in starting solution, 10%. Initial polymerization T = 100°C styrene conversion, 30% and initiator, tert-butyl peracetate, 0.09%. Suspension polymerization suspending agent, 0.6% ferf-butyl peroxide, 0.4% and water/(rubber -f monomer) = 1.2. Suspension cycle 2 hrs at 120°C, l hr at 140°C, and 2 hrs at 155°C. 

Typically, practical graded dielectric RAMs are constructed of discrete layers, with properties changing from layer to layer. A technique for reducing the reflection from the front face of a flat absorber is to use semiconductive foams obtained by impregnation with carbon or dispersion of carbon fibrils. A careful combination of these foams with an internal magnetic layer of the iron-filled elastomer type leads to wide bandwidth materials which can operate readily between 4 and 18 GHz [29] as shown in Figure 8.3,... 

It is the purpose of this review paper to examine the relatively newer uses of these elastomer types as resin modifiers within the broad range of epoxy-based coating systems. 

These products represent additional advances made by polymer scientists and formulating chemists. They use unique molecular building blocks and polymers, sometimes of different families than strictly acrylic, leading to numerous hybrids involving other polymer and elastomer types emerging very recently. In addition to the properties noted above, HI products retain virtually all of the performance features of earlier variants. 

Grade Name Elastomer Type Matrix Phase Supplier... 

Factors involved in the selection of vulcanization systems must include the type of elastomer, type and quantity of zinc oxide and fatty acid, rate of vulcanization, required resistance to fatigue, and service conditions. It is also recommended that use of nitrosamine-generating accelerators be avoided. 

Another aspect is that modem elastomer parts are made of a wide variety of elastomer types and/or are combined with metals or other plastics in material composites for the purpose of realizing additional functions such as sensory aspects, insertions, strength elements, textiles attached by gluing or vulcanization, lubricant coatings, installation elements, flocculation applications, paint coats, etc. 

Elastomer type Properties Engage I Engage II Engage m... 

A morphological analysis revealed that the blends and composites which contain ethylene ethyl acrylate-maleic anhydride polymer exhibit a better elastomer phase dispersion with smaller domain sizes in comparison to the other elastomer. The addition of the carbon nanotubes also improves the mechanical properties of the samples for both elastomer types [83]. 

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