Preparation of long-chain fatty acid chlorides

Summary A rapid method has been found for preparing the long-chain fatty acid chlorides, which eliminates purification by distillation. It gave a quantitative yield of product containing less than 1.5% free acid. The method involves treating the free acid with phosphorus pentachloride or trichloride in an inert organic solvent and removing the excess chlorinating agent by washing the solvent phase with water. Phosphorus pentachloride and Skellysolve “F” were preferred for laboratory preparations. For commercial purposes however either chlorinating agent could be used in a variety of inert organic solvents. Infrared analysis was found to give a rapid measure of the free acid content of the prepared acid chlorides. Presented at the fall meeting, American Oil Chemists' Society, Philadelphia, Pa., Oct. 10–12, 1955. Issued as N. R. C. No. 4240.     

Retarding effects of DNA on the autoxidation of liposomal suspensions

Deoxyribonucleic acid (DNA) is associated with the cell membrane of prokaryotes and the inner nuclear membrane of eukaryotes. The unsaturated fatty acids of phospholipids, which constitute the bilaminar structure of membranes, undergo autoxidation in the presence of O₂. Calf thymus DNA was incubated with methyl archidonate-enriched phosphatidyl choline liposomes in order to study the effect of DNA upon the oxidation of phospholipids while present in their natural in vivo bilayer configuration. DNA retarded the rate of lipid oxidation and the TBA test, but it did not alter the induction period. These results suggest that DNA is scavenging free radicals produced within the phospholipid bilayer.     

Performance of treated hybrid fiber reinforced-thermoplastic composites under extreme conditions. IV. Use of glass fiber and sawdust as hybrid fiber

The mechanical properties and dimensional stability of hardwood aspen in the form of sawdust and surface-treated glass fiber-polystyrene composites were evaluated under various extreme conditions, e.g., variation in the testing temperature (from +25° to ?20°C), exposure to boiling water and heat in an oven at +105°C. The compatibility of wood fiber with glass fiber and with polystyrene improved by precoating the wood fiber with a coupling agent, e.g., 8% isocyanate, 4% silane and polymer. The mechanical properties of the composites, in particular, treated sawdust/glass fiber-filled composites, increased under extreme conditions in comparison with those filled with nontreated sawdust/glass fiber. Under the same conditions, dimensional stability also supports this observation.     

Characterization of polymer‐layered silicate (clay) nanocomposites by transmission electron microscopy and X‐ray diffraction: A comparative study

Several polymer‐layered silicate (clay) nanocomposites (PLSNs) were analyzed by transmission electron microscopy (TEM) and wide‐angle X‐ray diffraction (XRD) in an effort to characterize the nanoscale dispersion of the layered silicate. The PLSNs investigated included thermoset (cyanate esters) and thermoplastic polymers (polystyrene, nylon 6, and polypropylene‐g‐maleic anhydride). The results of this study reveal that the overall nanoscale dispersion of the clay in the polymer is best described by TEM, especially when mixed morphologies are present. XRD is useful for the measurement of d‐spacings in intercalated systems but cannot always observe low clay loadings (<5%) or be used as a method to identify an exfoliated nanocomposite where no XRD peaks are present (constituting a negative result). Most importantly, the study showed that XRD is not a stand‐alone technique, and it should be used in conjunction with TEM. Our studies suggest that new definitions, or a clarification of existing definitions, are needed to properly describe the diversity of PLSN nanostructures seen in various materials. Published 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1329–1338, 2003     

Reinvestigation of the System Na3AlF6-Li3AlF6

A partial phase diagram for the system Na₃AlF₆-Li₃AlF₆ was constructed from DTA and X-ray diffraction measurements. A region of solid solution extends from Na₃AlF₆ to the limiting composition Na₂LiAlF₆. At compositions between Na_1.5Li_1.5AlF₆ and NaLi₂AlF₆ a cubic phase resembling the mineral cryolithionite is stable over a narrow range of temperatures, which shifts progressively to higher temperatures with increasing lithium content. A single phase can be quenched from samples annealed within this range except near the ideal cryolithionite composition (Na_1.5Li_1.5AlF₆) where the upper temperature limit is too low to permit recombination of two solid phases to cryolithionite even with prolonged annealing. Cryolithionite precipitated from aqueous solution, a sample of the mineral, and the solid solutions containing from 53 to 65 mole % Li₃AlF₆ have identical powder patterns except for differences of lattice constants. Solid solubility of Na₃AlF₆ in Li₃AlF₆ reaches 30 mole % at the eutectic temperature.     

Analysis of polymer blend morphology by transmission and reflection light scattering techniques

Optical inspection is a potentially powerful and practical tool to collect information on polymer blend morphology for on-line quality and process control. This paper describes two approaches for the characterization of polymer blend materials by multiple light scattering. A quantitative evaluation of spectral turbidimetry (scattering of transmitted light) is presented and an adaptation of this technique for monitoring particle size, independent of the volume fraction is demonstrated. Such a procedure is applicable to materials in film form. A different approach is presented for the analysis of nearly spherical particles in optically thick samples: the diffuse reflection pattern surrounding the position of incidence of a focused light beam on the surface of the turbid medium is scanned by a single side imaging system. A spectral pseudo-transmittance signal processing technique provides particle size information again independent of the volume fraction: Both techniques have been tested using well characterized polystyrene microspheres suspended in water as well as poly(methyl) (methacrylate)/polystyrene polymer blends.     

Progress and recent trend in MILD combustion

Moderate or intense low oxygen dilution(MILD)combustion plays a significant role in the mitigation of combustion-generated pollutants and greenhouse gases whilst meeting thermal efficiency needs.However,due to the lack of the fundamental knowledge on this combustion,there is a misconception that MILD combustion should be established by high preheating of the air,which has limited its application.Our research and development on this combustion has been performed for several years. We have found that the requ...     

An ion-exchange process with thermal regeneration XI. The Ca/Na selectivity behavior of weakly acidic resins

Calcium-sodium selectivity data for a number of carboxylic acid resins were obtained under constant solution conditions with the object of determining the effects of variations in resin structure. As weakly acidic resin ionization is pH dependant, plots of selectivity versus fraction ionized were obtained from measurements over a range of pH values.Calcium retention was found to be favoured by higher levels of resin ionization, greater degrees of crosslinking, by deliberate building in of chelating residues, and in commercial resins by acrylic over methacrylic acid types. In experimental composite resins comprising micro particles of active material embedded in an inert matrix, no difference in behavior of the two acid types was discernible, but the methacrylic variety is preferred for low calcium retention because of its more weakly acidic nature. The enhanced performance of a snake-cage acidic resin containing polyether and of a copolymer system containing ether groups in this regard was attributed to their greater swelling tendencies, arising from the incorporation of hydrophilic groups. In another copolymer system, however, the presence of amide groups was found to approximately halve the high affinity of acrylic acid resins for calcium, in particles which had normal swelling properties, and a reasonable high exchange capacity of 8.4 meq/g.