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The partitioning of the 1-butene co-unit between crystalline and non-crystalline regions of random, homogeneous propylene 1-butene copolymers (PB) has been studied by WAXD, 13 C NMR, and FTIR in a series of copolymers with a concentration of 1-butene ranging from 2 to ∼ 20 mol%. A partial inclusion of the 1-butene co-unit in the crystallites is identified by the expansion of the unit cell,...
Izod impact strength was determined as a function of temperature for polypropylene (PP)/ethylene-co-octene elastomer (EOR) blends and nanocomposites to determine the effect of PP molecular weight, elastomer MFI, EOR octene content and MMT content on the ductile-brittle (D-B) transition temperature. The D-B transition temperature decreases with increased molecular weight of the PP (H = high, M = medium...
We report on the influence of parameters controlling filler dispersion and mechanical reinforcement in model nanocomposites. We elaborate a series of nanocomposites and present a structural characterization of silica dispersion in polymer matrix for several particle sizes and polymer matrices, at all relevant scales, by coupling Small Angle X-ray Scattering and Transmission Electronic Microscopy....
The aim of this study was to synthesize graft copolymers of poly(methacrylic acid)-g-poly(ɛ-caprolactone) by a two-step process. In a first part, a macromonomer of 2-hydroxyethylmethacrylate-poly(ɛ-caprolactone) (HEMA-PCL) was synthesized by coordinated anionic Ring Opening Polymerization (ROP). Then graft copolymers were obtained via Reversible Addition Fragmentation chain Transfer (RAFT) copolymerization...
Electrospun nanofibers were captured directly between two steel rods that functioned as the “grips” of the tensile testing apparatus. Tension was applied to the selected nanofiber by displacing one of the grips at controlled rates or in steps. The stress was revealed by the deflection of a nanofiber, caused by the drag force from a broad stream of air, which flowed perpendicular to the fiber at a...
High-molecular-weight poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) are blended at different ratios and their crystallization behavior was investigated. Solely homo-crystallites mixtures of PLLA and PDLA were synchronously and separately formed during isothermal crystallization in the temperature (T c ) range of 90–130 °C, irrespective of blending ratio, whereas in addition to...
Cross-linked samples of natural rubber (NR) and synthetic cis-1,4-polyisoprene (IR) were instantaneously expanded to a predetermined strain ratio, α s , using a newly-designed high-speed tensile tester. Crystallization behavior after the cessation of deformation was investigated. The high-cycle wide-angle X-ray diffraction (WAXD) measurements could successfully reveal the drastic progress...
Activating enzymes in organic solvents is of great interest in current biotechnology. Amphiphilic conetworks have been shown to activate entrapped enzyme molecules in such media. Although successful, the loading of such conetworks is limited by the diffusion of protein molecules. In order to overcome this, we designed a new polyoxazoline-based polymer conetwork that allows the enzyme entrapment during...
We use molecular dynamics method (MD) combined with multi-particle collision dynamics (MPCD) method to investigate the effects of poiseuille flow on the conformations and migration behaviors of semiflexible chains confined in two infinite flat planes. At low shear rates, the semiflexible chain keeps semirigid conformation in the plane parallel to the infinite flat wall. At high shear rates, the semiflexible...
In this report, ferroelectric behaviors were investigated as a function of temperature and poling frequency for a uniaxially stretched poly(vinylidene fluoride-co-trifluoroethylene) 50/50 (mol./mol.) film. A variety of ferroelectric behaviors, including normal ferroelectric, antiferroelectric-like, and paraelectric behaviors, were observed by varying temperature, poling frequency, and poling electric...
The miniemulsion polymerization of styrene mediated by N-(2-methyl-2-propyl)-N-(1-diethylphosphono-2,2-dimethylpropyl)-N-oxyl (SG1) at 396 K is modeled up to high conversion as a function of the targeted chain length (TCL) and particle diameter. Thermal self-initiation and diffusional limitations are explicitly accounted for. The importance of the compartmentalization of nitroxide, initiator and macroradicals...
Polystyrene colloid particles armored by Montmorillonite clay (MMT) were prepared by free-radical polymerization in dispersion. MMT was pre-modified with cationic amphiphilic block copolymer of poly(styrene-b-2-hydroxyethyl acrylate) (PS-b-PHEA), and the obtained (PS-b-PHEA)-MMT modified clay was used as stabilizer in dispersion polymerization. The impact of (PS-b-PHEA)-MMT loading on the particle...
The morphology of an immiscible blend of polypropylene and (ethylene-octene) copolymer has been studied for different flow conditions. Samples were taken and quenched at the exit of a slit die attached to an extruder. For a statistical analysis of the minor phase droplets, scanning electron images of cryo-fractured samples were used. The size distribution and anisotropy of the minority phase droplets...
How the viscoelastic asymmetry affects the concentration fluctuation and its manifestation in rheology of miscible polymer blends are examined in this work. The linear viscoelastic stress of polymer blends is divided into the components stress and the stress due to concentration fluctuation. The dynamic coupling between the fluctuation in concentration and the stress is represented by the two-fluid...
Positron lifetime spectroscopy is used to develop a new approach to characterize the individual interfaces in ternary polymer blends and hence determine composition dependent miscibility level. This approach has its genesis in KSR and KRZ models for the evaluation of hydrodynamic interaction parameters (α ij ). The method successfully applied for binary blends (single interface) earlier is...
In the Sn(Oct) 2 catalyzed bulk copolymerization of l-lactide (LLA) and a large amount of branching comonomer 2,2-bis(hydroxymethyl)butyric acid (BHB) (LLA/BHB/Sn(Oct) 2 ratio is 5:1:0.05, 135°C), low molecular weight of copolymers with inhomogeneous structure were generated. MALDI-TOF mass spectrum demonstrated that the lower molar mass fraction was dominated with the BHB homo-polycondensation...
We study the coaxial spinning of poly(lactic acid) (PLA) with polypropylene (PP) in a core/sheath configuration. PP core /PLA sheath and PLA core /PP sheath fibers maintain the high breaking strength that PP and PLA exhibit individually, showing marked improvement in strength over previous reports of PP/PLA blend fibers. Crystalline morphologies are greatly affected...
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