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The film samples of polylactide/montmorillonite (PLA/MMT) nanocomposite were formed by compression molding, film extrusion or melt blowing. The orientation of the single-layer platelets of fully exfoliated MMT was probed in these films with X-ray diffraction utilizing analysis of 2-D WAXS patterns and the pole figure technique. The reflections of the (0 2 0) and (2 1 0) crystallographic planes of MMT, both perpendicular to the plane of the platelet, were studied. It was found that the texture of MMT created upon processing is the (1 0 0) planar texture, i.e. with MMT platelets oriented preferentially parallel to the film plane. That texture becomes significantly stronger and sharper with increasing shear deformation, according to the following order: compression molding → extrusion → blow molding. At the blow ratio of 7 the maximum of MMT orientation distribution reaches value of 8 m.r.d. and the estimated Hermans orientation factor of the platelet normal with respect to the film normal, is very high, f001 = 0.96. The results obtained by X-ray pole figure technique were verified positively by direct TEM observations.

Poly( l -lactide), PLLA, belongs to the most widely used biodegradable polyesters. These polymers have attracted great attention in recent years due to their excellent material properties, which give a rise to potential applications in various commercial areas. Previously, PLLA reprocessing in a co-rotating twin-screw extruder was used as a model test for material recycling. It may be assumed basing on this study, that PLLA technological wastes may be suitable for reuse, for example, as an additive for neat PLLA. In order to verify such suitability of reprocessed PLLA its degradability under industrial composting conditions was studied at the static composting open-air pile. Incubation of this material in water at 70 °C (abiotic conditions) was also conducted. The progress of the degradation process was monitored by surface changes and measurements of sample weight loss and changes in the PLLA molecular weight. The molecular level structure of the water soluble degradation products of PLLA samples was determined by electrospray ionization multistage mass spectrometry (ESI-MS n ). Lactic acid and its oligomers terminated by hydroxyl and carboxyl end groups were identified as hydrolytic degradation products. The obtained results indicated that in selected environments (industrial composting and incubation under abiotic conditions) hydrolytic degradation via random ester bond scission occurs preferentially. It was demonstrated, that multi-reprocessing of PLLA did not significantly affect the rate of degradation and only slightly affected the disintegration progress of the PLLA samples.

The results of the investigations of the effect of blow-up ratio of nanocomposite poly(lactic acid) (PLA) films on the mechanical properties determined under static tension are discussed. Investigated films contain additives in the form of a montmorillonite (MMT) nanofiller (LC sample) or MMT and poly(methyl methacrylate) (PMMA) as a modifier (LCM sample) or MMT and poly(ethylene glycol) (PEG) as a plasticizer (LCG sample). Using the X-ray diffraction (XRD) method, it was found that the screw shape of the co-rotating twin-screw extruder, applied to prepare a granulated nanocomposite, significantly influenced the dispersion of MMT within the PLA matrix. The PLA film containing the additives and subjected to a proper extrusion blow molding have better mechanical properties as compared to those of a neat PLA (L sample) film. These properties were found to be the best when the blow-up ratio (R) of the nanocomposite films was equal to 4. The images obtained by means of the transmission electron microscopy (TEM) confirmed that ordering of the MMT platelets within the PLA matrix occurred during the film blowing, which induced an improvement in the film mechanical properties. The presented results prove usefulness of the extrusion blow molding as a method of manufacturing nanocomposite films based on the PLA matrix.

Results are presented of an investigation of the effect of blow moulding ratio of a nanocomposite polylactic acid (PLA) film, containing (i) a montmorillonite (MMT) nanofiller or (ii) MMT and poly(methyl methacrylate) (PMMA) as a modifier or (iii) MMT and poly(ethylene glycol) (PEG) as a plasticiser, on transmission of water vapour, oxygen and carbon dioxide, as well as on the arrangement of the MMT platelets within the PLA matrix. It was found that introduction of 5 wt. % of MMT into the PLA matrix significantly improved barrier properties of the film, which was reflected by a decrease in the transmission of water vapour by more than 40%, of oxygen by almost 40%, and of carbon dioxide by up to more than 80%. A further decrease in the film permeability (by 10–27%) was achieved by extrusion blow moulding, the less-permeable films being obtained at a blow moulding ratio of 4. Such a reduction in the permeability was caused mainly by ordering of the MMT platelets within the PLA matrix during the blow moulding process, which has been proved by transmission electron microscopy (TEM). The obtained results confirm the effectiveness of extrusion blow moulding as a technique for manufacturing nanocomposite films containing PLA as a matrix, which exhibit favourably modified barrier properties.

The results of investigations of the influence of shungite content (up to 50 weight %) in polypropylene matrix on the selected functional and processing properties of the composites are presented. Among others, mechanical strength (Fig. 2—5), impact strength (Fig. 6), and melt flow rate (Fig. 7) were evaluated. Thermal characteristics of the composites prepared was studied by differential scanning calorimetry (DSC, Fig. 8, 9) and thermogravimetry (Fig. 10,11). Thermo-mechanical properties were determined by dynamic mechanical analysis (DMA, Fig. 12). Surface and volume resistivity has been studied as well (Fig. 14). Wettability was also determined (Fig. 13) and on this basis the values of surface free energy were calculated according to Owens-Wendt method. It was found that shungite filled polypropylene composites were hydrophobic materials less susceptible to longitudinal strain at tension, showing lower impact strength, better anti-electrostatic properties and worse electro-insulating ones.

Influence of the unit energy (Eu) of corona discharge used for modification of pure polylactide (PLA) and polylactide nanocomposite (PLAC) containing 5 wt% of an aluminosilicate nanofiller (Cloisite 30B) on water (ΘW) and diiodomethane (ΘD) contact angles as well as on surface free energy (γs) of these polymers was studied. ΘW and ΘD as advancing contact angles were measured with use of a goniometer while γs was calculated by the Owens–Wendt method. It was found that ΘW increased with the rising Eu while ΘD remained approximately constant. Assuming Eu = const, it could be stated that the increase in γs was much more evident for PLA than for PLAC. This increase resulted practically from the change in the polar component of γs because the dispersive component for the two materials only slightly decreased with increase in Eu.

An array of carbazoles (23 examples) can be synthesized from substituted biaryl azides at 60 degrees C using substoichiometric quantities of Rh(2)(O(2)CC(3)F(7))(4) or Rh(2)(O(2)CC(7)H(15))(4).

Influence of two types of montmorillonite nanofillers (Cloisite 30B and Nanofil 2), two kinds of organic modifiers (poly(methyl methacrylate) and ethylene/vinyl alcohol copolymer) and two types of compatibilizers (polycaprolactone and poly(ethylene glycol)) on transmission rates of water vapour, oxygen, and carbon dioxide through polylactide films is discussed. It was found that Cloisite 30B decreased the film permeability much more than Nanofil 2. All the modifiers and compatibilizers reduced the carbon dioxide transmission rate, while only the modifiers reduced the transmission rates of water vapour and oxygen. The sample containing 75, 5, and 20 wt% of polylactide, Cloisite 30B, and poly(methyl methacrylate), respectively, appeared to be the film with the best barrier properties from among 27 studied materials. The permeabilities of this film to water vapour, oxygen and carbon dioxide decreased by 60, 55 and 90%, respectively, as compared to those of the pure polylactide film. Physicochemical processes associated with the transmission rates of various substances through the polylactide nanocomposite films are still not sufficiently recognised and require further investigation.

The chromium-catalyzed allylic oxidation of triterpene 1 with O2 and N-hydroxyphthalimide (NHPI, 5 equiv) formed endoperoxide 2 in 76% yield at ambient temperature. Unlike standard allylic oxidations, this oxidation is catalytic in chromium because oxygen, not the chromium reagent, is the oxidant. This oxidation is sensitive to the precise structure of the substrate. The endoperoxide is only formed if ring A is unsaturated and ring C contains an enone. A mechanism is proposed that involves the coupling of two stabilized radicals on rings A and C to form endoperoxide 2.

Five-membered ring peroxides were prepared in one step in 31–86% yield from readily accessible β,γ-epoxy ketones and H2O2. The reaction proceeded via a tetrahydrofuran, which was converted to the thermodynamically favored 1,2-dioxolane. The product contains a leaving group, which can be displaced to synthesize analogues of the plakinic acid natural products.

Iridium(I) catalyzes the intramolecular benzylic C−H bond amination of ortho-homobenzyl-substituted aryl azides to produce indolines at 25 °C.

The use of a rhodium(II) carboxylate catalyst enables the mild and stereoselective formation of carbazoles from biaryl azides. Intramolecular competition experiments of triaryl azides suggested the source of the selectivity. A primary intramolecular kinetic isotope effect was not observed, and correlation of the product ratios with Hammett sigma(+) values produced a plot with two intersecting lines with opposite rho values. These data suggest that electronic donation by the biaryl pi-system accelerates the formation of rhodium nitrenoid and that C-N bond formation occurs through a 4pi-electron-5-atom electrocyclization.

Iridium(I) catalyzes the intramolecular benzylic C-H bond amination of ortho-homobenzyl-substituted aryl azides to produce indolines at 25 degrees C.