Hydrocarbon resistance

There are also a number of nonaerospace civiHan appHcations for this material. Small diaphragms have found limited use in automotive and related appHcations. These are used because of the material s exceUent fatigue life and hydrocarbon resistance. A compound containing methacrylates functions as a soft liner for dentures (16), providing extended life, shock isolation, and resistance to microbial attack. 

As experience shows (w hich, however, is not quite in agreement wfith the theory), the strongest current generation occurs when the hydrocarbon resistivity lies between 10 to 10 ohm-cm and decreases beyond this range. 

The nylons have found steadily increasing application as plastics materials for speciality purposes where their toughness, rigidity, abrasion resistance, good hydrocarbon resistance and reasonable heat resistance are important. Because of their high cost they have not become general purpose materials such as polyethylene and polystyrene, which are about a third of the price of the nylons. 

Thermoplastic polyester rubbers are also block copolymers of polyethers and polyesters. The polyester groups are capable of crystallisation and the crystal structures act like cross-links. These materials have good hydrocarbon resistance. Similar thermoplastic polyamide rubbers are also now available. 

Suitable grades are usable in contact with food and are used for food packaging. Chemical resistance is generally good but polymethylpentenes are attacked by oxidizing acids, chlorinated solvents, certain oxidants and aromatic hydrocarbons. Resistance to aliphatic hydrocarbons, ketones, gasoline and kerosene is limited. 

PP/NBR-V is marketed for its hydrocarbon resistance, which competes with conventional nitrile rubber. 

While we did not test sufficient numbers of regenerated protoplasts to accurately determine the transformation frequency to aromatic hydrocarbon resistance, these frequencies were certainly high. Chang and Cohen (37) reported transformation frequencies of 10-80% using the same lysozyme-PEG method and similar quantities of plasmid DNA. The naphthalene transformants retained their degradative ability through at least six successive transfers. 

Degradation of elastomers used in transfer lines and hoses by aromatic fuel components is undesirable. For this reason, elastomers used in fuel storage and distribution systems are often made of hydrocarbon-resistant elastomers such as Viton , polyvinyl chloride (PVC) and Teflon . 

This structure is similar to that of the copolymer TFE and ethylene, except that the random onentation of the methyl group from nonstereospeciftc free radical copo-lymenzation of propylene affords a noncrystalline structure [35] The relatively low fluorine content (54%) of these elastomers compared with VDF-based elas tomers (66-69 5%) makes them significantly less resistant to swelling by hydrocarbons Because of strict alternation, these elastomers have a relatively high glass transition temperature ( 2 °CJ and consequently limited low temperature properties Furthermore, they must be polymerized with a cure site monomer or receive a postpolymerization treatment to adequately activate them for vulcanization [36] To counteract the limited cure response, low-temperature flexibility, and hydrocarbon resistance, these polymers have also been modified with substantial amounts (ca 35 wt %) of VDF [37, 38] This provides some improvements but inevitably decreases the resistance to bases and polar solvents... 

Figure 3.1 Polyphosphazene elastomers of general formula, [NP(OCH2CF3) (OCH2(CF2), CF2H)]b, fabricated into fuel lines, O-rings, gaskets, and other hydrocarbon-resistant devices. Reproduced by permission of the Firestone Tire and Rubber Company, and Ethyl Corporation.

AATCC TM 118-Oil repellency hydrocarbon resistance test, equivalent to ISO 14 419... 

Properties Colorless transparent solid odorless. D 1.19 (15C). Insoluble in water, gasoline, oils, and fats soluble in low molecular weight alcohols, esters, benzene, and chlorinated hydrocarbons. Resistant to weathering. Combustible. 

American Association of Textile Chemists and Colorists (AATCC) (1997), AATCC Test Method 118 Oil Repellency Hydrocarbon Resistance Test, Research Triangle Park, NC, AATCC. 

T)oly (fluoroalkoxyphosphazenes) (PFAP) (I) are semi-inorganic poly-mers that contain a phosphorus nitrogen chain. Pendant fluoroalkoxy groups are attached to the phosphorus to impart hydrolytic stability and hydrocarbon resistance. 

Whereas the paraffin hydrocarbons resist to a high degree the action of oxidizing agents, ethylene and its homologues are oxidized readily. Aqueous solutions of chromic acid oxidize ethylene to carbon dioxide. Neutral or alkaline solutions of potassium permanganate form, along with other substances,... 

J. W. Simmons, S. Kulkami, and 0. M. Ekiner. Method for separating hydrocarbon-containing gas mixtures using hydrocarbon-resistant membranes. US Patent 7 025 804, assigned to L Air Liquide, Societe Anonyme A Directoire et Conseil De Surveillance Pour L Etude et L Exploitation Des Procedes Georges Claude (Paris, FR) N/A (, April 11, 2006. 

The resistance of EVM to hydrocarbon fluids is dependent upon the vinyl acetate content. Higher levels of vinyl acetate increase the polarity of the polymer and, therefore, increase the hydrocarbon resistance. 

Simmons JW, Kulkami S, Ekiner OM. Method for separating hydrocarbon-containing gas mixtures using hydrocarbon-resistant membranes. [101] US patent 7025804, assigned to L Air Liq-... 

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