The photodegradation of poly(vinyl chloride)—V The effect of wavelength of irradiation on the dehydrochlorination reaction

For a purified sample of poly(vinyl chloride), it is found that radiation of wavelength less than 300 nm causes dehydrochlorination. It appears that polychromatic radiation yields a constant ratio of concentrations of polyenes, even from the very early stages of reaction. It is proposed that energy transfer is an important step in the photodecomposition of poly(vinyl chloride).     

Mikroerscheinungen bei der Rißausbreitung in Hochpolymeren und ihre Beziehung zur Kontinuumsmechanik

Ohne Zusammenfassung     

Thermoplastic polyurethanes containing 12-hydroxymethylabietanol

Thermoplastic polyurethane elastomers incorporating the resin acid-derived 12-hydroxymethylabietanol (12-HMA) were prepared, and some physical properties are reported. A polyester macroglycol was prepared from 12-HMA, adipic acid, and ethylene glycol. This macroglycol then was combined with either poly(tetramethylene adipate) glycol (PTAd) or poly(ethylene adipate) glycol (PEAd) and 1,4-butanediol to give a glycol blend of 300 average hydroxyl equivalent weight (OHE). The glycol mixture then was combined with diphenylmethane 4,4′-diisocyanate (MDI) (NCO/OH = 1.0) to give urethane polymers soluble in tetrahydrofuran. Polymers were prepared with 0, 5, 10, 15, 20, and 25%, by weight, 12-HMA with PTAd as the other macroglycol and with 0, 10, 15, and 20% 12-HMA with PEAd as the other macroglycol. At 15% 12-HMA, polymers were made from glycol mixtures having 275 and 350 average OHE to demonstrate the effect of changing the hard-segment concentration. The presence of 12-HMA is shown to have its maximum effect on tensile properties at 15–20% in the PTAd series and at 10% in the PEAd series. In general, this effect is an increase in tensile strength and modulus and a decrease in elongation when compared with a similar polymer without the 12-HMA.     

Synthesis of four diastereomeric 3,5-dialkoxy-2,4-dimethylalkanals by a simple extension of the non-aldol aldol process to bis(propionates)

[formula: see text] The synthesis of all four diastereomers of bis(propionates), 3,5-dialkoxy-2,4-dimethylalkanals, by non-aldol aldol chemistry is described. The epoxy alcohols (3, 4) were converted into the mesylates (9, 11) which were cleanly rearranged to the desired 3,5-bis(oxygenated)-2,4-dimethylalkanals (10, 12) in high yield. The epoxy mesylates (13, 16) gave the desired products (14, 17) in good yield on treatment with TMSOTf and a hindered base.     

Chiral discrimination of limonene by use of beta-cyclodextrin-coated quartz-crystal-microbalances (QCMs) and data evaluation by artificial neuronal networks

The enantiomeric composition of the chiral flavoring agent limonene was analyzed by means of a quartz-crystal microbalance (QCM) sensor. As chiral selectors three different modified beta-cyclodextrins were investigated. The selector molecules were applied as mixtures in different polysiloxane matrices. The chiral separation factors alpha for limonene obtained at 30 degrees C by gas chromatography and by use of the QCM sensor were comparable. Evaluation of sensor data was performed by use of an artificial neuronal network (ANN); this enabled prediction of the enantiomeric composition of the gas mixtures.