EPDM elastomer

EPDM elastomers EPDM lonomers EPDM rubber... 

Elastomers. Ethylene—propylene terpolymer (diene monomer) elastomers (EPDM) use a variety of third monomers during polymerization (see Elastomers, ethyiene-propylene-diene rubber). Ethyhdenenorbomene (ENB) is the most important of these monomers and requires dicyclopentadiene as a precursor. ENB is synthesized in a two step preparation, ie, a Diels-Alder reaction of CPD (via cracking of DCPD) with butadiene to yield 5-vinylbicyclo[2.2.1]-hept-2-ene [3048-64-4] (7) where the external double bond is then isomerized catalyticaHy toward the ring yielding 5-ethyhdenebicyclo[2.2.1]-hept-2-ene [16219-75-3] (ENB) (8) (60). 

Here the PFGE results for two elastomers EPDM and polyisoprene [24] are compared. The EPDM investigated here is, for an elastomer, highly crystalline (30%). While crystalline domains are expected to behave as diffusion barriers for Xe, this was thought to be an interesting case for the determination of the diffusion coefficient as a function of the diffusion time A. As a comparison the completely amorphous polyisoprene was used. 

Of great industrial interest are the copolymers of ethene and propene with a molar ratio of 1/0.5, up to 1/2. These EP-polymers show elastic properties and, together with 2-5 wt% of dienes as third monomers, they are used as elastomers (EPDM). Since they have no double bonds in the backbone of the polymer, they are less sensitive to oxidation reactions. As dienes, ethylidenenorbomene, 1,4-hexadiene, and dicyclopentadiene are used. In most technical processes for the production of EP and EPDM rubber in the past, soluble or highly disposed vanadium components are used [69]. Similar elastomers can be obtained with metallocene/MAO catalysts by a much higher activity which are less colored [70-72]. The regiospecificity of the metallocene catalysts toward propene leads exclusively to the formation of head-to-tail enchainments. The ethylidenenor-bornene polymerizes via vinyl polymerization of the cyclic double bond and the tendency to branching is low. The molecular weight distribution of about 2 is narrow [73]. 

Although, in th case, extractive distillation provides a solution in itself, it may be interesting to improve its effectiveoeu by avoiding complications of this type, especially since cydopentadiene. and. to a lesser degree, piperylene, have many specific appHcadons. The former is used for elastomers (EPDM, polynorbomene. transpolypentenamer etc). 

A specific attention has been paid to the mechanochemical generation of X in unsaturated elastomers, EPDM, ABS, PVC and polyolefins [243, 252]. This synthetical approach exploits processing operations producing free radicals. In situ chemical reactions can be performed during some important industrial processes like mastication of rubber and extrusion, mixing or reaction injection molding of plastics. 

The time accelerated aging method for electric wires and cables requires a high dose rate irradiation, but the exposure to polymer in air results only the oxidation of surface when the dose rate is higher. I previously reported the methodology study of time accelerated irradiation of elastomer (2). The study showed two appropriate methods, one was irradiation in pressurized oxygen at room temperature the other was irradiation at 70°C in air. The article studied the effect of higher dose (up to 10 MGy) irradiation on ethylene-propylene-diene elastomer (EPDM) by using the time accelerated method. Irradiation at 70°C in air was chosen as the time accelerated irradiation condition because of the experimental convenience. 

Table I-V shows the compounding receipt of the samples used in this study.In th etable phr means pers per hundred resin (rubber). The thickness of the samples was about 0.5 mm. EPDM-3, 4, 5, 6 and 7 are the series of the compounding formula of the curing by low sulfur. EPDM-2 contains the relatively higher sulfur with Hypalon (Chlorosulphonated polyethylene) that increases tensile strength of elastomer. EPDM-1, 8 and 10 were crosslinked by peroxide. Triallyl isocyanurate in EPDM-1 is a multi-functional compound that increases the concentration of network.

Elastomer, EPDM type C T = 65°C AIBN, 0.13% suspending agent, 0.6% water/(rubber + monomer) = 1.4 and elastomer in the initial vinyl chloride + rubber mixture, 8.3%... 

Ghosh et al. (32) had developed a new vulcanization technique to mitigate the cure-rate mismatch of NR/EPDM blends by introducing a multifunctional additive, namely, DIPDIS. In order to control the curative diffusion from the nonpolar to polar elastomer, EPDM has made more polar through its reaction with DIPDIS. Although EPDM used in the investigation has a low unsaturation content (5%), it will react with DIPDIS and yield rubber-bound intermediates as shown in Fig. 15.2 (32). It was... 

During the last few years we have developed methods for rapid cross-linking of polyethylenes, ethylene-propylene-diene elastomers (EPDM)2 and linear unsaturated polyesters using UV light for initiation. Efficient crosslinking to high gel content has been obtained for these polymer systems, which contain small amounts of UV-absorbing initiator and a multifimctional monomer (a crosslinker),... 

EPDM Packed with polymer pieces of cross-linked elastomer (EPDM) THF 0.4 ml/minute Inverse GPC 39... 

Oiefinic, partially cross-linked elastomer EPDM, EPR, BR, NR, IR, CBR, etc. For manufacturing automotive components Ellul 1994... 

Keltan Thermoplastic elastomers, EPDM, PP/EPDM DSM Polymers Int. 

Flow measurement is by magnetic meters with ethylene-propylene-diene elastomer (EPDM) lining and Hastelloy C electrodes. The control valve can be a rubber-lined butterfly valve with a rubber-coated or Monel disc. 

Figure 3.23 SEM micrographs showing the blend morphology at different elastomer (EPDM) concentrations for physical blends (upper) and highly crosslinked TPVs (lower).

When comonomers are introduced, this destroys chemical regularity of chain units. It thereby reduces or even eliminates crystallinity, depending on the comonomer content. An illustration which is also important in applications is provided by ethylene copolymers. If propene is introduced into polyethylene, the level of crystallinity is reduced (therefore also diminishing its modulus and density). This is because it limits the possibilities for a crystalline structure to those sequences made up of (CH2)i units. A whole family of new compounds, called Low Density Linear PolyEthylenes (LDLPE), was developed during the 1980s. Ethylene/propene (50/50) copolymers form amorphous compounds which are used as elastomers (EPDM). 

Keywords ABS, acrylic-elastomers, ASA, AXS, blends, CBR, compat-ibilization, CPE, CSM, CSR, elastomer, EPDM, EPR, EVAc, EVAl, LLDPE, miscibility, NBR, PB, PIB, rubber, SBR, SBS, SEBS, SIS. 

The Swiss company, WW Fischer, offers PTFE (Teflon PTFE or Hostaflon), PBT (Celanex, Crastin, Ultradur or Valox) or PEEK (Victrex) insulator material options in its 405 series of cylindrical connectors according to the requirements of working temperature and other criteria. PEEK is an expensive polymer which tends to be employed when other materials fail to meet the specification requirements of the application. Other Fischer connector types use polyamide-imide (Torlon) or POM (Celcon, Delrin or Hostaform). Elastomeric seals used by Fischer in conjunction with their connectors are made from acrylonitrile-butadiene rubber (NBR N BUNA) or to MIL-P-25732, fluoroelastomer (FPM VITON), polychloroprene elastomer (CR Neoprene), ethylene-propylene diene elastomer (EPDM) and styrene-ethylene-butadiene-styrene thermoplastic elastomer (TPE-S or TPE-O) where each compound is followed by its trade name. Fischer s Swiss competitor, Lemo, manufactures a similar range of connectors including the Redel types which have a plastic body. 

The objective of the melt blending is to break the elastomer (EPDM) into as fine particles as possible and to disperse them uniformly in the PPBC matrix. This is achieved by means of a twin screw extruder, with a specially designed screw profile that facilitates intimate mixing. 

Production of this blend requires a proper choice of raw materials and also an appropriate production technology. The toughening effect depends very much on the elastomer (EPDM) affinity to polypropylene copolymer, its degree of dispersion in the matrix, and the distribution of its particle size. 

Controlled polymerization, copolymerization possible to produce elastomers Low cost, wide product range, 0.2 MI material Very low MI product and wide product range Production of elastomers, EPDM and EP rubber... 

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