Polymeric hydrocarbon

Aluminum oxide has been the most widely used catalyst (151). At 320°C and 1.01—1.42 MPa, 50—66% conversion to alcohol based on the ether was obtained. Ethanol produced by the direct hydration of ether generally has a foul odor owing to the presence of polymeric hydrocarbon material, which can be removed by washing the aqueous alcohol with ether (152). 

Terpene monomers are another class of interesting natural monomers because they give, on polymerization, hydrocarbon therplastic resins that exhibit a high degree of tackiness useful in pressure sensitive tapes [25]. They are also used for sizing paper and textile materials. Terpene-phenol resins are effective heat stabilizers for high-density polyethylene. 

Polymeric hydrocarbon by-products accompany the products of the latter two reactions. The structures of the products are clear evidence of the occurrence of 1,2-alkyl shifts leading to more stable carbocationic intermediates. ... 

The principal laws for the fluorination of polymeric hydrocarbons are the same as those described above for the simple case. Direct fluorination has been used extensively in organic chemistry (but only since the early 1970s) in low-temperature methods, where the fluorine is strongly diluted with some inert gas (helium, argon, nitrogen, krypton). One can note the La Mar, aerosol-based, and liquid-phase fluorination methods. 

Dielectric Loss. Usually, the dielectric loss of plasma polymerized hydrocarbon is larger than that of the conventional polymer by more than one order of magnitude. This difference is supposed to be caused by the oxidation of the film (J34). For both samples of PPE, a loss peak appeared at -30 °C at the measurement frequency of 1 KHz. The activation energy of this peak was 0.68 eV as shown in Fig. 8 for both samples. This value was almost same as... 

The polymeric hydrocarbon also acts as a binder of the particles, holding them together so as to formulate a propellant grain. Ammonium perchlorate (AP) is a typical crystalline oxidizer and hydroxy-terminated polybutadiene (HTPB) is a typical polymeric fuel. When AP and HTPB are decomposed thermally on the propellant surface, oxidizer and fuel gases are produced, which diffuse into each other and react to produce high-temperature combustion gases. 

HMX and RDX are energetic materials that produce high-temperature combustion products at about 3000 K. If one assumes that the combustion products at high temperature are HjO, Nj, and CO, rather than COj, both nitramines are considered to be stoichiometricaUy balanced materials and no excess oxidizer or fuel fragments are formed. When HMX or RDX particles are mixed with a polymeric hydrocarbon, a nitramine pyrolant is formed. Each nitramine particle is surrounded by the polymer and hence the physical structure is heterogeneous, similar to that of an AP composite pyrolant... 

While polymeric hydrocarbons have been used as illustrations for simplicity, it is important to note that the principles discussed apply to all polymers, organic as well as inorganic, and natural as well as synthetic, and to elastomers, plastics, and fibers. 

Coke Formation. As discussed above, coke refers to both polycyclic, condensed polymeric hydrocarbons formed during the reaction of... 

Insoluble polymeric hydrocarbon formed on the anode. f A small amount... 

Linear polyethylene (hdpe), which has a repeating unit of 4-CHr CH24 , is a typical thermoplastic with a glass transition temperature Tt below room temperature. Its mechanical properties permit its use as both a plastic and a fiber. From a structural viewpoint, this polymeric hydrocarbon is the least complex of all polymers. 

Chap. 13 Polymeric Hydrocarbons with Pendant Groups... 

Chap. 13 Polymeric Hydrocarbon with Fondant Qroupa... 

Polymeric hydrocarbons, such as polyolefins, are readily combustible and can actually serve as a fuel source. In contrast, polytetrafluoroethylene (ptfe) does not bum in air but burns in oxygen or in nitrogen-oxygen mixtures which have a very high oxygen concentration. 

The rate of transmission of gases and vapors through polymeric films varies with the structure of both the diffusate molecule and the polymer. Polymers with polar groups, such as cellulose and cellulose acetate, are permeable to water vapor, but polymeric hydrocarbons, such as PIB, are essentially impervious to water vapor. 

Polymeric hydrocarbon elastomers, such as natural rubber, are cross-linked or vulcanized by the use of sulfur, which reacts with the carbon of the unsaturated bonds in polymer molecules to form a bridge between two molecules so that one polymer molecule is covalently bonded to a second polymer molecule (6). 

If sufficient crosslinks of this type occur in the polymeric hydrocarbon, all molecules are joined in a single giant molecule. The characteristic property of a crosslinked polymer is its intractibility above the softening point or melting point that is normally observed in the uncrosslinked base polymer. 

Polyacetylene and poly(p-phenylene) (PPP) are two polymeric hydrocarbons with a unique property both are conducting polymers on doping. Polyacetylene, a... 

Whether polymerized model membrane systems are too rigid for showing a phase transition strongly depends on the type of polymerizable lipid used for the preparation of the membrane. Especially in the case of diacetylenic lipids a loss of phase transi tion can be expected due to the formation of the rigid fully conjugated polymer backbone 20) (Scheme 1). This assumption is confirmed by DSC measurements with the diacetylenic sulfolipid (22). Figure 25 illustrates the phase transition behavior of (22) as a function of the polymerization time. The pure monomeric liposomes show a transition temperature of 53 °C, where they turn from the gel state into the liquid-crystalline state 24). During polymerization a decrease in phase transition enthalpy indicates a restricted mobility of the polymerized hydrocarbon core. Moreover, the phase transition eventually disappears after complete polymerization of the monomer 24). 

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