Hybrid effects on mechanical properties of polyoxymethylene

The present study investigated fracture and various mechanical properties of polyoxymethylene (POM) hybrids in tension and in flexure. The hybrids examined consisted of short glass fibers (GF) and spherical glass beads (GB). Comparisons are made between experimentally observed values and predictions based on the rule-of-hybrid mixtures for hybrid strength, modulus, impact strength, fracture toughness, and strain energy release rates. Results indicated that tensile strength, flexural modulus, and fracture toughness of POM/GB/GF hybrid composites can be estimated from the following rule-of-hybrid mixtures where P_POM/GB and P_POM/GF are the measured properties of the POM/GB and POM/GF composites, and χ_POM/GB and χ_POM/GF are the hybrid ratio (by volume) of the glass bead and that of glass fiber, respectively. In view of this, none of the aforementioned properties show any signs of a hybrid effect. Flexural strengths, impact strengths, and strain energy release rate all showed the existence of a negative hybrid effect where negative deviation from the rule-of-mixtures behavior was observed. The latter was closer to the estimation based on the inverse rule-of mixtures.     

Hydrogenation of methyl sorbate and soybean esters with polymer-bound metal catalysts

New polymer-bound hydrogenation catalysts were made by complexing PdCl₂, RhCl₃·3H₂O, or NiCl₂ with anthranilic acid anchored to chloromethylated polystyrene. The Pd(II) and Ni(II) polymers were reduced to the corresponding Pd(O) and Ni(O) catalysts with NaBH₄. In the hydrogenation of methyl sorbate, these polymer catalysts were highly selective for the formation of methyl 2-hexenoate. The diene to monoene selectivity decreased in the order: Pd(II), Pd(O), Rh(I), Ni(II), Ni(O). Kinetic studies support 1,2-reduction of the Δ4 double bond of sorbate as the main path of hydrogenation. In the hydrogenation of soybean esters, the Pd(II) polymer catalysts proved superior because they were more active than the Ni(II) polymers and produced lesstrans unsaturation than the Rh(I) polymers. Hydrogenation with Pd(II) polymers at 50~100 C and 50 to 100 psi H₂ decreased the linolenate content below 3% and increasedtrans unsaturation to 10~26%. The linolenate to linoleate selectivity ranged from 1.6 to 3.2. Reaction parameters were analyzed statistically to optimize hydrogenation. Recycling through 2 or 3 hydrogenations of soybean esters was demonstrated with the Pd(II) polymers. In comparison with commercial Pd-on-alumina, the Pd(II) polymers were less active and as selective in the hydrogenation of soybean esters but more selective in the hydrogenation of methyl sorbate. Presented at ISF-AOCS Meeting, New York, April 1980.     

Analysis of autoxidized fats by gas chromatography-mass spectrometry: V. Photosensitized oxidation

The role of singlet oxygen in oxidation was studied by analyzing hydroperoxide isomers in unsaturated fats and esters by gas chromatography-mass spectrometry (GC-MS). On oxidation photosensitized with methylene blue at 0 C, methyl oleate produced a 50–50% mixture of 9- and 10-hydroperoxides, linoleate a mixture of 66% conjugated (9+13) and 34% unconjugated (10+12) hydroperoxides, and linolenate a mixture of 75% conjugated (9+12+13+16) and 25% unconjugated (10+15) hydroperoxides. Cottonseed, safflower, and corn oil esters showed, as in soybean esters, the presence of varying amounts of 12-hydroxy esters derived from the corresponding hydroperoxide at low peroxide values. Since these oils do not contain linolenic acid, a likely source of the 12-hydroperoxide is linoleic acid by photosensitized oxidation. Several lines of evidence support the conclusion that singlet oxygen may contribute to the unique hydroperoxide composition of vegetable oil esters at low levels of oxidation. In the presence of photosensitizers such as methylene blue and chlorophyll, the unique hydroperoxide composition (high levels of 10- and 12-hydroperoxides) obtained in soybean esters was similar to that produced by oxidation at low peroxide values. In contrast, a normal hydroperoxide composition was produced, as expected from the fatty acid composition of soybean oil esters, when singlet oxygen quenchers such as β-carotene and α-tocopherol were used and when the esters were treated with carbon black to remove natural photosensitizers. GC-MS analyses of the derived unsaturated alcohols provided indirect evidence for 12-hydroperoxy-9,13-diene in soybean esters as expected by photosensitized oxidation of linoleate. Presented at the AOCS Meeting, San Francisco, California, April 29–May 3, 1979. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

DanNet: the challenge of compiling a wordnet for Danish by reusing a monolingual dictionary

This paper is a contribution to the discussion on compiling computational lexical resources from conventional dictionaries. It describes the theoretical as well as practical problems that are encountered when reusing a conventional dictionary for compiling a lexical-semantic resource in terms of a wordnet. More specifically, it describes the methodological issues of compiling a wordnet for Danish, DanNet, from a monolingual basis, and not—as is often seen—by applying the translational expansion method with Princeton WordNet as the English source. Thus, we apply as our basis a large, corpus-based printed dictionary of modern Danish. Using this approach, we discuss the issues of readjusting inconsistent and/or underspecified hyponymy hierarchies taken from the conventional dictionary, sense distinctions as opposed to the synonym sets of wordnets, generating semantic wordnet relations on the basis of sense definitions, and finally, supplementing missing or implicit information.     

Ultrahigh-efficiency, very narrowpassband, tunable optical filter

Recently developed technologies have been uniquely integrated to produce optical filters with unprecedented performance. The precise design and fabrication of narrow-passband and high-efficiency optical filters with a central frequency of 532 nm are reported. Measurements with these filters demonstrate a performance that accurately mirrors the design specification, with one filter having a passband of 70 pm and an efficiency greater than 90% and the second filter having a passband of 7 pm and an efficiency greater than 80%.     

Providing lubricity in food fat systems

Lubricity, in particular mouthfeel, is an important factor in production of vegetable oil bases for food product formulations. Certain functional characteristics are necessary for good texture at various temperatures. These characteristics are dependent on degree of unsaturation, fatty acid distribution, and degree of geometrical isomerization during processing. Proper selectivity and activity of hydrogenation catalysts used in hardening of the oils are essential. Sufficient solid fat content must be balanced by necessary oxid ative stability. Products discussed include salad oils and their formulations in pourable and spoonable salad dressings, mayonnaises, frying oils, imitation dairy products, margarines and bakery shortenings. Past, present and future industry technology will be evaluated for each type of food fat product. Customer needs have greatly affected the course of research in this area.     

Performance of a solid oxide fuel cell couple operated via in situ catalytic partial oxidation of n-butane

The operation of a pair of anode-to-anode-facing solid oxide fuel cells (SOFCs) via in situ catalytic partial oxidation (CPO) of n-butane was investigated. In this simple “no-chamber” setup, butane is partially oxidized by heterogeneous reactions inside the porous anodes, providing processed fuel and the heat required for SOFC operation. The cell couple yielded a power density of up to 270 mW cm⁻², and the maximum total power obtained was 1.2 W with cell sizes of 13 mm × 23 mm. The maximum electrical efficiency was 1.3%. High CO concentrations of up to 1000 ppm were detected in the exhaust gas, indicating that the cell couple could not efficiently consume the complete provided fuel. A flame, lit at the exhaust, minimized the carbon monoxide level while having insignificant influence on the cell performance. Thermal insulation of the cell couple improved the output remarkably, showing the strong influence of temperature on cell performance. The two cells had a distance of only 2 mm, suggesting a potential for high volumetric power densities in multi-cell configurations for a self-sustained combined heat and power system.