Melt blending of poly(ethylene terephthalate) with polypropylene in the presence of silane coupling agent

A silane coupling agent (SCA) was used as a compatibilizer for polypropylene-poly(ethylene teraphthalate) (PP-PET) blends with 20, 40, 50, and 60% PET compositions by weight. PP-PET mixtures were blended with and without an SCA by a single-screw extruder. The effect of silane modification on the tensile and impact properties of the blends was investigated. The morphology and thermal behavior of the blends were examined with scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. The presence of the SCA used in this work extensively improved the mechanical properties of the blends. Mechanical properties were found to be highly de-pendent on the numbers Of extrusions. SEM studies showed that substantially different morphology with better adhesion existed when SCA-treated blends were compared to non-treated PP-PET blends. The presence of individual melting temperatures of the polymers in all compositions with no significant T,, depression indicated that PET and PP were crystallized separately. (C) 2003 Wiley Periodicals, Inc

Oxidation of model compound emulsions for alkyd paints under the influence of cobalt drier

A systematic investigation on the oxidation of different model compounds (including methyl oleate (MO), ethyl linoleate (EL), and methyl linolenate (MLn)) in emulsions under the influence of an emulsifiable cobalt drier was performed. Raman spectroscopy, attenuated total reflectance (ATR)-FTIR, and 1H NMR were used. Raman spectroscopy proved to be a powerful technique at following the oxidation of these model compounds in emulsions not only after but also during the water evaporation. Raman and ATR-FTIR (D2O was used instead of H2O) investigations clearly demonstrated that there was essentially no observable chemical change during the water evaporation. The oxidation of model compounds in emulsions, after the water evaporation, was found to be similar to the oxidation of bulk/solvent-borne model compounds. The presence of an emulsifier (sodium dodecyl sulfate) and water did not show any significant effects on the oxidation of the model compounds. An increase in the intensity of conjugated double bonds and isolated trans-double bonds was first observed, and followed by a decrease. More than 90% of double bonds disappeared for EL and MLn after 13 days of oxidation as examined by 1H NMR, which may be attributed to the addition of radicals to double bonds (propagation-like reaction) and the -scission of double-bond-containing radicals into by-products. The number of double allylic group in the model compounds also showed a significant influence on the rate of oxidation for emulsions after water evaporation

Drying activity of oxovanadium(IV) 2-ethylhexanoate in solvent-borne alkyd paints

Oxovanadium(IV) 2-ethylhexanoate was established as a new primary drier for alkyd-based paints. A series of experiments has demonstrated an excellent drying activity toward solvent-borne alkyd resins of different oil length at considerably lower metal concentration than optimal for commercial cobalt(II) 2-ethylhexanoate. The behavior in real paint was simulated on formulations bearing inhibitor of autooxidation. The detailed studies of the drying process have shown that the relatively slow initial step of autooxidation reaction, when compared with cobalt compounds, is compensated for by the absence of the induction times. Furthermore, the active oxovanadium(IV) species are not consumed during the drying processes as evidenced by EPR spectroscopic measurements.2-ethylhexanoatu oxovanadičitý vykazuje vlastnosti typické pro primární sikativy. Uvedené experimenty ukazují výbonou sikativační aktivitu vůči alkydovým pryskyřicím různé olejové délky při výrazně nižších koncentracích než je běžné u komerčních 2-ethylhexanoatu kobaltnatého. Chování v reáné formulaci bylo simulováno na sysytémech s inhibitory autooxidace