EP Rubbers

This, however, is possible only in special EP rubber compounds as noted above. 

Ethylene Propylene (EP, EPDM) is an o-ring rubber compound that is compatible with most water-based chemicals. It is good with caustic soda, detergents, water treatment chemicals, steam, and wastewater and with food processes like milk, beer, and soups. EP rubber compound is petroleum based and for this reason it should never come into contact with petroleum based chemicals. 

Fig. 11.1 Maleic anhydride graft process for baled EP rubber. [Reprinted by permission from R. C. Kowalski, Fit the Reactor to the Chemistry, in Reactive Extrusion, M. Xanthos, Ed., Hanser, New York, 1992.]...

Contrary to the production of EP-rubbers, from a statistical point of view the formation of gel is much more pronounced in BD polymerization. This as-... 

Figure 1 Polymer enchainment patterns occurring in polyethylene (PE), ethylene-propylene copolymer (EP), and polypropylene (PP) chains (HDPE = crystalline high-density polyethylene, LLDPE — linear low-density polyethylene, LDPE = low-density polyethylene, EP rubber = elastomeric ethylene-propylene copolymer).

Homogeneous vanadium-based catalysts formed by the reaction of vanadium compounds and reducing agents such as organoaluminum compounds [10-12] are used industrially for the production of elastomers by ethylene/propene copolymerization (EP rubber) and ethylene/propene/diene terpolymerization (EPDM rubber). The dienes are usually derivatives of cyclopentadiene such as ethylidene norbomene or dicyclopentadiene. Examples of catalysts are Structures 1-4. Third components such as anisole or halocarbons are used to prevent a decrease in catalyst activity with time which is observed in the simple systems. 

The increase in radical activity with unsaturation is also indicated by the data in Table I, which clearly indicate that products with a higher graft copolymer content can be obtained with EPDM elastomers than with EP rubbers the composition of these products varies with the diene content (15). 

Morphological examination of the reaction products also provided evidence that, with EPDM elastomers, the grafted and crosslinked rubber remained dispersed in the matrix as particles with an average diameter of 2-5(i. The structure remained unaltered, even after mechanical actions such as those required for transformation into manufactured articles. On the other hand, with EP rubbers, particle morphology was markedly altered under the same transformation conditions. 

PP-MA (0-20) dispersed phase domain size vs. vol. fraction of compatibilizer / also blends containing EP rubber Rosch, 1995 Rosch and Miilhaupt, 1995 1993... 

Commercial impact modified PP were developed during the early 1970 s by melt blending about 5 to 25 wt% ethylene-propylene rubbers (EP or EPDM) with the polypropylene homopolymer via extruder compounding [Holzar, 1966]. Some LDPE or HOPE is often used to assist the dispersabUity of the EP rubber and enhance the impact/modulus balance of the product [D Orazio,... 

At present, there is only one commercial source of the polyamide/polycarbonate blends (Dexcarb , Dexter Corp.). According to their patent, the blend was compatibilized by using a combination of a polyesteramide elastomer and a maleated olefinic polymer, such as male-ated polypropylene or EP rubber [Perron, 1984 1988]. However the degree or the efficiency of compatibilization achieved is unknown, since the added components are not known to be miscible or compatible with the polycarbonate. Nevertheless, the data sheet indicated good properties including a high notched Izod impact strength of > 700 J/m (Table 15.24). 

Figure 3.12 Dynamic mechanical spectroscopy of LDPE-EP rubber blend in tensile mode using synthetic frequency multiplexing of 1, 2, 5, 10, and 20 Hz.

Polydiene rubber is a common low voltage electrical insulation material, used because of its low electrical conductivity and elasticity. But, it can degrade rapidly by peroxidation, even if there are antioxidant stabilisers in the system, which can lead to electrical shortages and fires. Polydiene rubbers are recently being replaced by saturated ethylene-propylene (EP) rubbers or plasticised PVC. 

Polydiene rubbers were used for many years in low voltage electrical insulation because of their low electrical conductivity and flexibility. However, the traditional rubbers degrade by peroxidation relatively rapidly even when stabilised with antioxidants. This frequently leads to fires due to electrical shortage and, in recent decades, they have been largely replaced with saturated elastomeric materials e.g. EP rubbers... 

Olefinic Thermoplastic Elastomers Blends of EPDM or EP rubbers with polypropylene or polyethylene, optionally eross-linked. Has low density, good dielectric and mechanical properties, and processibility but low oil resistance and high flammability. Processed by extrusion, injection and blow-molding, thermoforming, and calendering. Used in auto parts, construction, wire jackets, and sporting goods. Also called TPO. 

Chlorinated paraffins (C12, 60% chlorine) Chlorinated paraffins (C23, 43% chlorine) lubricant, EP detergents Chlorinated paraffins (C12, 60% chlorine) Chlorinated paraffins (C23, 43% chlorine) lubricant, EP lubricating oils Chlorinated paraffins (Cl2, 60% chlorine) Chlorinated paraffins (C23, 43% chlorine) lubricant, EP metalworking Chlorinated paraffins (Cl2, 60% chlorine) Chlorinated paraffins (C23, 43% chlorine) lubricant, EP rubber Chlorinated paraffins (Cl2, 60% chlorine) Chlorinated paraffins (C23, 43% chlorine) lubricant, EP sealants Chlorinated paraffins (Cl2, 60% chlorine) Chlorinated paraffins (C23, 43% chlorine) lubricant, ethylcellulose Glyceryl (triacetoxystearate) lubricant, explosives... 

There are polymers which have high ozone resistance. ENB terpolymers are but one example. Refer to EP Rubbers for a brief discussion. 

In the last decade, considerable progress was observed in the field of PO/compatibil-izer (predominantly on the base of PO-g-MA)/organo-surface-modified clay nanocomposites. Polyethylene (PE), polypropylene (PP), and ethylene-propylene (EP) rubber are one of the most widely used POs as matrix polymers in the preparation of nanocomposites [3,4,6,30-52]. The PO silicate/silica (other clay minerals, metal oxides, carbon nanotubes, or other nanoparticles) nanocomposite and nanohybrid materials, prepared using intercalation/exfoliation of functionalized polymers in situ processing and reactive extrusion systems, have attracted the interest of many academic and industrial researchers because they frequently exhibit unexpected hybrid properties synergisti-cally derived from the two components [9,12,38-43]. One of most promising composite systems are nanocomposites based on organic polymers (thermoplastics and thermosets). 

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