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Melt-flow-induced crystallization of polyethylene blends having tailored ultrabroad molar mass distribution affords extended-chain ultrahigh molar mass (UHMWPE) nanophases resembling nanofibers which effectively reinforce the polyethylene matrix. Unparalleled by state-of-the-art high density polyethylene (HDPE), the resulting melt-processable “all-polyethylene” single component composites exhibit...
Nanophase separation during injection molding of high density polyethylene (HDPE) together with polyethylene reactor blend (RB) additives that have ultrabroad bimodal molar mass distribution and a high content of ultrahigh molar mass polyethylene (UHMWPE), produces thermoplastic all-polyethylene composites reinforced with extended-chain UHMWPE nanostructures formed in situ. Neither alien fibers, inorganic...
Systematic variation of copolymers (Poly (ethylene-covinylacetate)) composition provide an opportunity to change matrix polarities and thus explore their effects on the polymer/filler interactions and composite properties. The main objective of this work is to study the effect of vinyl acetate (VA) content on the extent of exfoliation and dispersion of thermally reduced graphite oxide (TrGO), as well...
The design of supported two- and three-site catalysts for ethylene polymerization and tailoring nanophase-separated polyethylene reactor blends represents the key to the development of advanced all-polyethylene nanocomposite materials exhibiting substantially improved performance and high resource-, eco- and energy efficiency. Two or three different single-site catalysts independently produce high...
A versatile gas phase mineralization process affords nanosheets containing a functionalized graphene (FG) core and a thin silica shell. The number of cycles, exposing FG to sequenced tetrachlorosilane and water vapors, controls the silica content and the silica shell thickness. The resulting high surface area core/shell nanosheets, containing 22 to 34 wt.-% silica, are used to immobilize single-site...
Novel families of elastomeric polyurethane (PU) nanocomposites are prepared by in-situ polymerization of diisocyanate with functionalized graphene nanosheets dispersions in polyether polyols. The influences of graphene dispersion, interfacial coupling and PU hard segment content on PU nanocomposite morphologies, mechanical and electrical properties are investigated. High shear mechanical dispensing...
Novel acrylic nanocomposites containing calcium phosphate/layered silicate hybrid nanoparticles have been developed for use in photochemical Rapid Prototyping processes like Structural Light Modulation (SLM) and Stereolithography (SL). When tertiary alkyl amines, protonated with phosphoric acid, were added to an acrylic suspension of calcium bentonite, the cation exchange of Ca 2+ rendered...
Polyethylene (PE)–boehmite nanocomposites were prepared by means of metallocene/MAO-catalyzed in-situ polymerization of ethylene in the presence of boehmites, which were rendered organophilic by modification with carboxylic acids such as stearic acid and undecylenic acid. Such organoboehmites are readily dispersed in the polymerization media such as toluene. Polymerization activity, filler dispersion...
The phenoxyimine catalyst (bis-(N-(3′,5′-diiodo-salicylidene)-2,6-difluoroaniline)-titanium(IV)-dichloride) was tailored to enable random and block copolymerisation of propylene and ethylene with compositions covering the entire feasible composition range. Well-defined high molecular weight diblock copolymers of the type PE-block-P(E-co-P), consisting of a semi-crystalline polyethylene and a soft...
High-throughput development of catalysts, initiators, and polymeric materials combines automated parallel catalyst synthesis and automated polymerization reactors. The reactors can be additionally equipped with on-line monitoring (ReactIR from Mettler) based on ATR-FT-IR technique. This powerful tool has proven to be a very valuable probe for high-throughput experiments. During copolymerizations of...
Syndiotactic polypropylene (sPP) compounds containing organophilic layered silicates were prepared by means of melt extrusion at 220 o C using a corotating twin screw extruder in order to examine the influence of the silicate modification and the addition of maleic-anhydride-grafted isotactic polypropylene (iPP-g-MA) as compatibilizer on morphology development and mechanical properties. Synthetic...
The reaction between oxazoline-functionalised polymer particles and bis(carboxylic acid)-terminated poly(tetrahydrofuran) (PTHF-COOH) was monitored by means of FTi.r. spectroscopy. Parameters such as particle size, content of functional groups, stoichiometry and temperature were varied to study their influence on conversion and reaction rate constants. Oxazoline conversion was primarily affected...
Novel α,ω-bis(1,3-oxazolin-2-yl)-terminated oligotetrahydrofurans with number average molecular mass of 2000 and 3700 g mol −1 were prepared via endcapping of bis(carboxypropyl)-terminated oligotetrahydrofuran with 1,4-bis(1,3-oxazolin-2-yl)-benzene in bulk at 250°C. Such liquid rubbers were added as chain extenders during melt processing of poly(butyleneterephthalate) to produce within a...
Ethene was copolymerized with N,N-bis(trimethylsilyl)-1-amino-10-undecene in the presence of homogeneous, MAO-activated rac-Me 2 Si(Benz[e]Ind) 2 ZrCl 2 to yield, upon hydrolysis of the silylated amines, short chain branched linear low density polyethylene (LLDPE) with pendent aminoalkyl groups. Aminofunctional LLDPEs were characterized by means of 1 H-n.m.r. FTi.r...
Blends of isotactic and syndiotactic polypropylene were studied by differential scanning calorimetry (d.s.c.), light transmission measurements and pressure-volume-temperature (PVT) measurements. D.s.c. measurements show the absence of any kind of melting point depression in the blends. Furthermore, the change of the ratio of crystallized i-PP and crystallized s-PP in the blends as a function of crystallization...
Blends of isotactic and syndiotactic polypropylene were studied by wide angle X-ray scattering (WAXS), small angle X-ray scattering (SAXS), light microscopy, scanning electron microscopy and atomic force microscopy. WAXS measurements show that both polymers crystallize in different unit cells already during precipitation from a common solvent. Both polymers have a very similar long period and lamella...
The morphology of syndiotactic polypropylene (s-PP), containing 91% racemic pentads, isothermally crystallized from the melt has been investigated by means of light microscopy, atomic force microscopy (AFM), and small-angle X-ray scattering (SAXS). Light microscopy shows a typical needle-like structure of crystalline entities at crystallization temperatures ranging from 115 to 150°C. Large bundles...
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