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Coatings nonpolar

Placed in aqueous solution, phospholipids spontaneously form a lipid bilayer (Figure 19.7) in which polar head groups lie on the surface, giving the bilayer an ionic coating. Nonpolar hydrocarbon chains of fatty acids lie buried within the bilayer. This self-assembly of phospholipids into a bilayer is a spontaneous process, driven by two types of noncovalent forces ... [Pg.656]

Capillary Electrochromatography Another approach to separating neutral species is capillary electrochromatography (CEC). In this technique the capillary tubing is packed with 1.5-3-pm silica particles coated with a bonded, nonpolar stationary phase. Neutral species separate based on their ability to partition between the stationary phase and the buffer solution (which, due to electroosmotic flow, is the mobile phase). Separations are similar to the analogous HPLC separation, but without the need for high-pressure pumps, furthermore, efficiency in CEC is better than in HPLC, with shorter analysis times. [Pg.607]

Zhou and colleagues determined the %w/w H2O in methanol by GG, using a capillary column coated with a nonpolar stationary phase and a thermal conductivity detector. A series of calibration standards gave the following results. [Pg.616]

The stationary phase in LC is a fine granular solid such as silica gel. It can be used as such (mainly for nonpolar compounds), or the granules can be modified by a surface-bonded coating that changes (reverses) the polarity of the gel. A very small selection of stationary phases is listed in Table 35.2. [Pg.249]

Finally, the dielectric properties of a nonpolar polymer are modified by inclusion of even small amounts of a polar comonomer. In coatings applications the presence of polar repeat units in an otherwise nonpolar polymer reduces the tendency for static buildup during manufacture, printing, and ultimate use. On the other hand, in dielectric applications this increases the power loss and must be kept to a minimum, even to the exclusion of polar initiator fragments. [Pg.469]

A number of chemical products are derived from Sasol s synthetic fuel operations based on the Fischer-Tropsch synthesis including paraffin waxes from the Arge process and several polar and nonpolar hydrocarbon mixtures from the Synthol process. Products suitable for use as hot melt adhesives, PVC lubricants, cormgated cardboard coating emulsions, and poHshes have been developed from Arge waxes. Wax blends containing medium and hard wax fractions are useful for making candles, and over 20,000 t/yr of wax are sold for this appHcation. [Pg.168]

Thin coatings contain in general many polar groups that promote adhesion. Low polar or nonpolar thick coatings (e.g., PE) are usually combined with polar adhesives to achieve the necessary bond strength against peeling. [Pg.154]

The need to paint the blends has also resulted in new painting systems. Recently, a nonpolar color coat based on a hydrogenated polybutadiene diol and melamine resin for TPO bumper fascia was invented. The breakthrough technology allows the elimination of the TPO pretreatment step such as adhesion promoter, flame, or plasma during manufacturing. The paintability of two different types of E-plastomers was evaluated. The olefinic white paint was found to provide excellent paint adhesion for both types of metallocene plastomers. Paint peeling was not observed in any of the test... [Pg.178]

Polymers with a sizable number of ionic groups and a relatively nonpolar backbone are known as ionomers. The term was first used for copolymers of ethylene with carboxylated monomers (such as methacrylic acid) present as salts, and cross-linked thermoreversibly by divalent metal ions. Such polymers are useful as transparent packaging and coating materials. Their fluorinated forms have been made into very interesting ion-exchange membranes (considered further below). [Pg.450]

TLC plates coated with the layer of polar adsorbent should be prewetted with a nonpolar solvent, such as benzene or n-heptane (n-hexane), to prevent deactivation of the adsorbent surface and to avoid glue up as a result of the penetration of the pores by lipid molecules and other impurities (i.e., wax). [Pg.253]

Early work relied on the use of packed columns, but all modern GC analyses are accomplished using capillary columns with their higher theoretical plate counts and resolution and improved sensitivity. Although a variety of analytical columns have been employed for the GC of triazine compounds, the columns most often used are fused-silica capillary columns coated with 5% phenyl-95% methylpolysiloxane. These nonpolar columns in conjunction with the appropriate temperature and pressure programming and pressure pulse spiking techniques provide excellent separation and sensitivity for the triazine compounds. Typically, columns of 30 m x 0.25-mm i.d. and 0.25-qm film thickness are used of which numerous versions are commercially available (e.g., DB-5, HP-5, SP-5, CP-Sil 8 CB, etc.). Of course, the column selected must be considered in conjunction with the overall design and goals of the particular study. [Pg.440]

Copper, aluminum, stainless steel, nickel, or glass tubes bent into various shapes to fit the dimensions of the column oven provide the container for column packings [126]. Neither copper mor aluminum tubing is recommended as both metals are readily SKlditsd active, oxide-coated films formed on the inner walls promote decomposition or tailing of labile and polar solutes. Ptalnless steel is adequate for nonpolar samples but its catalytic activity precludes the analysis of labile solutes. Nickel, after acid passivation, and glass are the most inert column materials. [Pg.588]

HPLC solvents (PDMS-coated fibres are incompatible with hexane). PDMS fibres are more selective towards nonpolar compounds and polyacrylate fibres towards polar compounds such as acids, alcohols, phenols and aldehydes. Another feature of SPME fibre selectivity is discrimination towards high-MW volatiles. SPME has successfully been applied to the analysis of both polar and nonpolar analytes from solid, liquid or gas phases. Li and Weber [533] have addressed the issue of selectivity in SPME. [Pg.130]

Analysis Techniques. The contents of the major breakdown products of xetralin (naphthalene and 1-methyl indan) present in the distillate were determined by gas-liquid chromatography using a Hewlett Packard Series 5750 Research Chromatograph with a 62m x 0.5mm diameter glass capillary SCOT column coated with nonpolar SE 30 liquid phase (see Reference (4 ) for details). [Pg.245]

The manufacturers of windshield coatings take advantage of the fact that the hydrophilic substances possess chemical structures that permit favorable intermolecular interactions with water. Chemical species capable of exhibiting hydrogen bonding, dipole-dipole interactions, or ion-dipole interactions with water are typically hydrophilic substances. Alternatively, hydrophobic substances typically are nonpolar molecules that exhibit only weak van der Waals interactions with water. [Pg.88]


See other pages where Coatings nonpolar is mentioned: [Pg.610]    [Pg.17]    [Pg.547]    [Pg.270]    [Pg.490]    [Pg.347]    [Pg.763]    [Pg.551]    [Pg.251]    [Pg.1065]    [Pg.2]    [Pg.34]    [Pg.1465]    [Pg.27]    [Pg.821]    [Pg.76]    [Pg.77]    [Pg.78]    [Pg.84]    [Pg.211]    [Pg.585]    [Pg.593]    [Pg.594]    [Pg.595]    [Pg.596]    [Pg.600]    [Pg.624]    [Pg.680]    [Pg.185]    [Pg.236]    [Pg.210]    [Pg.212]    [Pg.263]    [Pg.273]    [Pg.241]   
See also in sourсe #XX -- [ Pg.159 ]




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Nonpolar

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