Abstract Current studies on novel, metallocenebased catalysts for the polymerization of α‐olefins have far‐reaching implications development new materials as well understanding basic reaction mechanisms responsible growth a polymer chain at catalyst center and control its stereoregularity. In contrast to heterogeneous Ziegler–Natta catalysts, by homogeneous, metallocene‐based occurs principally single type metal with defined coordination environment. This makes it possible correlate...

Pd2+-exchanged graphite oxide and chemically derived graphenes therefrom were employed as supports for Pd nanoparticles. The influence of catalyst preparation, carbon functionalization, morphology on the catalytic activity in Suzuki−Miyaura coupling reactions was investigated. catalysts characterized by means spectroscopy (FT-IR, solid-state 13C NMR, AAS, XPS), X-ray scattering (WAXS), surface area analysis (BET, methylene blue adsorption), electron microscopy (TEM, ESEM). In contrast to...

Glycidol represents a latent cyclic AB2-type monomer that can be polymerized in ring-opening multibranching polymerization (ROMBP). Hyperbranched aliphatic polyethers with controlled molecular weights and narrow weight distribution have been prepared via anionic of glycidol rapid cation-exchange equilibrium. 1,1,1-Tris(hydroxymethyl)propane (TMP) was partially deprotonated (10%) used as initiator for the carried out under slow addition conditions to minimize without well cyclization. 13C NMR...

Polymer nanocomposites are defined as polymers in which small amounts of nanometer size fillers homogeneously dispersed by only several weight percentages. Addition just a few percent the nanofillers has profound impact on physical, chemical, mechanical and electrical properties polymers. Such change is often favorable for engineering purpose. This nanocomposite technology emerged from field plastics, potentially expanded its application to structural materials, coatings, packaging...

Abstract Dwindling fossil resources, surging energy demand and global warming stimulate growing for renewable polymer products with low carbon footprint. Going well beyond the limited scope of natural polymers, biomass conversion in biorefineries chemical dioxide fixation are teamed up highly effective tailoring, processing recycling polymers. “Green monomers” from biorefineries, “renewable oil”, gained plastics' bio wastes, render synthetic polymers without impairing their property profiles...

Abstract Untersuchungen an neuen Metallocenkatalysatoren zur Polymerisation von α‐Olefinen haben gegenwärtig weitreichende Auswirkungen auf die Entwicklung neuer Materialien und auch unser Verständnis der grundlegenden Reaktionsmechanismen, für das Wachstum Polymerketten einem Katalysatorzentrum deren Stereoregularität verantwortlich sind. Im Gegensatz zu heterogenen Ziegler‐Natta‐Katalysatoren erfolgt mit homogenen Metallocenkatalysator im Prinzip einheitlichen Metallzentren definierter...

Abstract Exfoliation of expanded GO represents an attractive route to functionalized graphenes as versatile 2D carbon nanomaterials and components a wide variety polymer nanocomposites. Thermally reduced graphite oxides (TrGO) with specific surface areas 600 950 m 2 · g −1 were obtained by oxidation followed thermal expansion at °C. Thermal post treatment 700 °C 1 000 increased content (81 97 wt.‐%) lowered resistivity (1 50 Ω cm). During melt extrusion PC, iPP, SAN PA6, exfoliation afforded...

Poly(propylene) compounds containing organophilic layered nanosilicates were prepared by means of melt extrusion at 210°C in order to investigate the role silicate modification and compatibilizer addition on morphology development mechanical properties. Synthetic sodium fluoromica was used as water swellable silicate, which rendered cation exchange with various protonated alkyl amines such butyl (C4), hexyl (C6), octyl (C8), dodecyl (C12), hexadecyl (C16), octadecyl (C18) amine. Interlayer...

Basic correlations between polymer morphology, silicate superstructures, glass temperature, stiffness and toughness of thermoset nanocomposites were investigated as a function layered type content. The based upon hexahydrophthalic anhydride-cured bisphenol A diglycidyl ether silicates such synthetic fluoromica (Fmica), purified sodium bentonite hectorite, all which rendered organophilic by means ion-exchange with various mono- difunctional alkyl ammonium ions. Enhanced was associated the...

Herein we report a very versatile new route to linear as well cross-linked terpene-based non-isocyanate poly(hydroxyurethanes) (NIPUs) and prepolymers derived from the novel cyclic limonene dicarbonate (CL). The catalytic carbonation of epoxidized with CO2 was monitored in presence both homogeneous tetrabutylammonium bromide (TBAB) heterogeneous silica supported 4-pyrrolidinopyridinium iodide (SiO2-(I)) catalysts. systematic variation catalyst type, pressure temperature enabled quantitative...

Soy- and linseed oil-based polyurethanes were prepared without using isocyanate monomers by curing carbonated soybean (CSBO) (CLSO) oils with different diamines. The conversion of the epoxidized seed carbon dioxide to form cyclic carbonates was catalyzed tetra-butylammonium bromide (TBAB) silica-supported 4-pyrrolidinopyridinium iodide (SiO2–(I)), which readily recovered requiring conventional purification solvent extraction TBAB. Carbonate formation monitored as a function catalyst type...

Thermally reduced graphite oxide (TRGO), containing only four single carbon layers on average, was combined with ammonium polyphosphate (APP) and magnesium hydroxide (MH), respectively, in polypropylene (PP). The nanoparticle’s influence different flame-retarding systems possible synergisms pyrolysis, reaction to small flame, fire behavior mechanical properties were determined. TRGO has a positive effect the yield stress, which is decreased by both flame-retardants acts as synergist regard...

The thermal degradation behaviour of nanocomposites based upon poly(propylene)/organoclay, modified with protonated octadecyl amine (C18) in comparison to that non-exfoliated microcomposites organoclay, butyl (C4), was studied by thermogravimetry. In the case nanocomposite, temperature at which volatilisation occurs increases as compared microcomposite. Moreover, oxidation process polymer is strongly slowed down nanocomposite high char yield both a physical barrier effect, enhanced ablative...

Abstract During the 1950's discoveries of Ziegler's organometallic catalyst systems and Natta's stereoselective olefin polymerization set stage for extraordinary progress in polymer science technology. Today advanced are available catalytic carbon bond formation by means polyinsertion, metathesis, coupling reactions, controlled radical polymerization. Modern processes polyolefins environmentally friendly meet demands a sustainable development. The architectures homo‐ copolymers based upon...

Abstract Two important rapid‐prototyping technologies (3D Printing and 3D Bioplotting) were compared with respect to the computer‐aided design free‐form fabrication of biodegradable polyurethane scaffolds meeting demands tissue‐engineering applications. Aliphatic polyurethanes based on lysine ethyl ester diisocyanate isophorone diisocyanate. Layer‐by‐layer construction was performed by Printing, that is, bonding together starch particles followed infiltration partial crosslinking...

Metallocene catalysis was employed to prepare model polypropylenes (PP) with very high molecular weights and narrow weight distributions (MWDs) of Mw/Mn ≈ 2, typical for "single site" metallocene catalysts. The viscoelastic properties PP melts were investigated by means oscillatory rheometry. Arrhenius WLF equations applied the influence temperature on rheology. With polypropylene samples it became possible determine onset plateau zone, reflecting rubber-like PP. For first time moduli...