Ethylene-propylene properties

It resembles polytetrafiuoroethylene and fiuorinated ethylene propylene in its chemical resistance, electrical properties, and coefficient of friction. Its strength, hardness, and wear resistance are about equal to the former plastic and superior to that of the latter at temperatures above 150°C. 

Properties ethylene-propylene resin Poly(vinylidene fluoride) Unfilled Glass-fiber- reinforced ethylene copolymer Cellulose- filled Glass-fiber- reinforced... 

Polypropylene polymers are typically modified with ethylene to obtain desirable properties for specific applications. Specifically, ethylene—propylene mbbers are introduced as a discrete phase in heterophasic copolymers to improve toughness and low temperature impact resistance (see Elastomers, ETHYLENE-PROPYLENE rubber). This is done by sequential polymerisation of homopolymer polypropylene and ethylene—propylene mbber in a multistage reactor process or by the extmsion compounding of ethylene—propylene mbber with a homopolymer. Addition of high density polyethylene, by polymerisation or compounding, is sometimes used to reduce stress whitening. In all cases, a superior balance of properties is obtained when the sise of the discrete mbber phase is approximately one micrometer. Examples of these polymers and their properties are shown in Table 2. Mineral fillers, such as talc or calcium carbonate, can be added to polypropylene to increase stiffness and high temperature properties, as shown in Table 3. 

Acrylonitrile—Butadiene—Styrene. ABS is an important commercial polymer, with numerous apphcations. In the late 1950s, ABS was produced by emulsion grafting of styrene-acrylonitrile copolymers onto polybutadiene latex particles. This method continues to be the basis for a considerable volume of ABS manufacture. More recently, ABS has also been produced by continuous mass and mass-suspension processes (237). The various products may be mechanically blended for optimizing properties and cost. Brittle SAN, toughened by SAN-grafted ethylene—propylene and acrylate mbbets, is used in outdoor apphcations. Flame retardancy of ABS is improved by chlorinated PE and other flame-retarding additives (237). 

ELASTOPffiRS,SYNTHETic-POLYcm.OROPRENE Elastop rs, SYNTHETIC-ETHYLENE-PROPYLENE-DIENE RUBBER). Tires, hoses, belts, molded and extmded goods, and asphalt products consume ca 80% of the reclaimed mbber manufactured. Typical properties of reclaimed mbbers are shown in Table 5. 

Ozonc-rcsjstant elastomers which have no unsaturation are an exceUent choice when their physical properties suit the appHcation, for example, polyacrylates, polysulfides, siHcones, polyesters, and chlorosulfonated polyethylene (38). Such polymers are also used where high ozone concentrations are encountered. Elastomers with pendant, but not backbone, unsaturation are likewise ozone-resistant. Elastomers of this type are the ethylene—propylene—diene (EPDM) mbbers, which possess a weathering resistance that is not dependent on environmentally sensitive stabilizers. Other elastomers, such as butyl mbber (HR) with low double-bond content, are fairly resistant to ozone. As unsaturation increases, ozone resistance decreases. Chloroprene mbber (CR) is also quite ozone-resistant. 

Although the mbbery properties of ethylene—propylene copolymers are exhibited over a broad range of compositions, weight percentages of commercial products generally range from 50 50 to 75 25 ethylene propylene. 

Table 1. Properties of Raw Ethylene—Propylene—Diene Co- and Terpolymers...

Property ECO, CO Epichlrohydrin homopolymer and copolymer Fluorosihcone EPDM Ethylene propylene CSM Chlorosulfonated polyethylene FPM Fluorocarbon elastomers... 

Two random copolymers of this type are of importance, ethylene-propylene copolymers and ethylene-but-l-ene copolymers. The use and properties of polypropylene containing a small quantity of ethylene in stereoblocks within the molecule has already been discussed. Although referred to commercially as ethylene-propylene copolymers these materials are essentially slightly modified polypropylene. The random ethylene-propylene polymers are rubbery and are discussed further in Section 11.9. 

These materials were first introduced by Du Pont in 1956 and are now known as Teflon FEP resins. (FEP = fluorinated ethylene-propylene.) Subsequently other commercial grades have become available (Neoflon by Daikin Kogyo and Teflex by Niitechim, USSR). These copolymers may be regarded as the first commercial attempt to provide a material with the general properties of PTFE and the melt processability of the more conventional thermoplastics. 

The use of ABS has in recent years met considerable competition on two fronts, particularly in automotive applications. For lower cost applications, where demands of finish and heat resistance are not too severe, blends of polypropylene and ethylene-propylene rubbers have found application (see Chapters 11 and 31). On the other hand, where enhanced heat resistance and surface hardness are required in conjunction with excellent impact properties, polycarbonate-ABS alloys (see Section 20.8) have found many applications. These materials have also replaced ABS in a number of electrical fittings and housings for business and domestic applications. Where improved heat distortion temperature and good electrical insulation properties (including tracking resistance) are important, then ABS may be replaced by poly(butylene terephthalate). 

TPEs from blends of rubber and plastics constitute an important category of TPEs. These can be prepared either by the melt mixing of plastics and rubbers in an internal mixer or by solvent casting from a suitable solvent. The commonly used plastics and rubbers include polypropylene (PP), polyethylene (PE), polystyrene (PS), nylon, ethylene propylene diene monomer rubber (EPDM), natural rubber (NR), butyl rubber, nitrile rubber, etc. TPEs from blends of rubbers and plastics have certain typical advantages over the other TPEs. In this case, the required properties can easily be achieved by the proper selection of rubbers and plastics and by the proper change in their ratios. The overall performance of the resultant TPEs can be improved by changing the phase structure and crystallinity of plastics and also by the proper incorporation of suitable fillers, crosslinkers, and interfacial agents. 

Greco et al. [50] studied the effect of the reactive compatibilization technique in ethylene propylene rubber-polyamide-6 blends. Binary blends of polyamide-6-ethylene propylene rubber (EPR) and a ternary blend of polyamide-6-EPR-EPR-g-succinic anhydride were prepared by the melt mixing technique, and the influence of the degree of grafting of (EPR-g-SA) on morphology and mechanical properties of the blends was studied. 

The most important olefins used for the production of petrochemicals are ethylene, propylene, the butylenes, and isoprene. These olefins are usually coproduced with ethylene by steam cracking ethane, LPG, liquid petroleum fractions, and residues. Olefins are characterized by their higher reactivities compared to paraffinic hydrocarbons. They can easily react with inexpensive reagents such as water, oxygen, hydrochloric acid, and chlorine to form valuable chemicals. Olefins can even add to themselves to produce important polymers such as polyethylene and polypropylene. Ethylene is the most important olefin for producing petrochemicals, and therefore, many sources have been sought for its production. The following discusses briefly, the properties of these olefmic intermediates. 

Proper selection of plastic matrix fire retardants and property enhancers offers acceptable combinations of impact properties and heat-distortion temperature (HDT) values for fire retardant plastics. This can be demonstrated by fire retardant styrenics. Fire retardant enhancers have special interest as property enhancers for example the addition of a highly flammable material such as ethylene propylene diene terpolyer (EPDM), dramatically improves the bromine efficiency of octabromodiphenyl oxide in ABS by increasing char-forming without changing the Sb-Br reaction. 

This is a nonpolar rubber with very little unsamration. Nanoclays as well as nanotubes have been used to prepare nanocomposites of ethylene-propylene-diene monomer (EPDM) rubber. The work mostly covers the preparation and characterization of these nanocomposites. Different processing conditions, morphology, and mechanical properties have been smdied [61-64]. Acharya et al. [61] have prepared and characterized the EPDM-based organo-nanoclay composites by X-ray diffracto-gram (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy... 

Chemical pretreatments with amines, silanes, or addition of dispersants improve physical disaggregation of CNTs and help in better dispersion of the same in rubber matrices. Natural rubber (NR), ethylene-propylene-diene-methylene rubber, butyl rubber, EVA, etc. have been used as the rubber matrices so far. The resultant nanocomposites exhibit superiority in mechanical, thermal, flame retardancy, and processibility. George et al. [26] studied the effect of functionalized and unfunctionalized MWNT on various properties of high vinyl acetate (50 wt%) containing EVA-MWNT composites. Figure 4.5 displays the TEM image of functionalized nanombe-reinforced EVA nanocomposite. 

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