Polarity hydrogenated hydrocarbon

Triacetin resistance is especially critical when filter tips are made in one location, stored, and then shipped to another location. For these operations, polyethylene-based adhesives are used because of their low polarity and therefore excellent resistance to triacetin. Where filter plugs are attached at the same location shortly after production, EVA-based adhesives are suitable and preferred. Both types of adhesives use low odor, clean tackifiers such as hydrogenated hydrocarbons or pure monomer resins (typically a-methylstyrene based). Rosin, rosin esters, and phenol-containing tackifiers are not acceptable. EVA-based adhesives use a higher level of wax (about 1 /3 of the formula) than polyethylene-based adhesives (5-20% wax) due to the lower crystallinity and slower set of EVA vs. PE. Application viscosities are 2000-5000 cP. 

Examples of empirical descriptors can be considered to be the -+ Taillander index (restricted to substituted benzenes), - second-grade structural parameters (restricted to alkenes), - polar hydrogen factor (restricted to halogenated hydrocarbons), - hydrophobic fragmental constants, - six-position number, Idoux steric constant, -> hydrophilicity index, - adsorbability index, -> bond flexibility index, and -+ atomic solvation parameter. 

The fluorescence quantum yield of anilines might depend on the excitation wavelengths, particularly those belonging to different absorption bands. In addition, this effect is generally more pronounced in nonpolar hydrocarbons than in polar hydrogen-bonding solvents,... 

Fluorination of plastics, usually polypropylene or polyethylene, is by far the most common modification. Containers are t3 ically manufactured by a blow molding process where they are protected by a fluorination process applied on line or, more frequently, off line. The first patent for this process was issued in 1975 and numerous other patents, some of them issued quite recently have made further improvements to the process. The latest processes use a reactive gas containing 0.1 to 1% fluorine to treat parison within the mold after it was expanded. Containers treated by this process are barrier to polar liquids, hydrocarbon fuels, and carbon fuels containing polar liquids such as alcohols, ethers, amines, carboxylic acids, ketones, etc. Superior performance is achieved when a hydrogen purge precedes the exposure of the container to oxygen. 

Water miscibility can rank from complete, for the more polar, hydrogen bonding solvent types (glycols, glycolethers, lower alcohols) via intermediate (higher alcohols, ketones and esters) to hardly miscible as in the case of most apolar hydrocarbon, chlorinated hydrocarbon and ether solvent types (Table 2.13). 

Proton chemical shift data from nuclear magnetic resonance has historically not been very informative because the methylene groups in the hydrocarbon chain are not easily differentiated. However, this can be turned to advantage if a polar group is present on the side chain causing the shift of adjacent hydrogens downfteld. High resolution C-nmr has been able to determine position and stereochemistry of double bonds in the fatty acid chain (62). Broad band nmr has also been shown useful for determination of soHd fat content. 

The physical properties of hydrofluorocarbons reflect their polar character, and possibly the importance of intermolecular hydrogen bonding (3). Hydrofluorocarbons often bod higher than either their PFC or hydrocarbon counterparts. For example, l-C H F bods at 91.5°C compared with 58°C for n-Q and 69°C for Within the series of fluorinated methanes, the boiling point reaches a maximum for CH2F2, which contains an equal... 

Poly(vinyhdene chloride) also dissolves readily in certain solvent mixtures (82). One component must be a sulfoxide or A/,Al-diaIk5lamide. Effective cosolvents are less polar and have cycHc stmctures. They include aUphatic and aromatic hydrocarbons, ethers, sulfides, and ketones. Acidic or hydrogen-bonding solvents have an opposite effect, rendering the polar aprotic component less effective. Both hydrocarbons and strong hydrogen-bonding solvents are nonsolvents for PVDC. 

---