Explanation for Micromorphologies Around Broken Fibers in Fiber-Reinforced Composites

Experimental observations on micromorphologies around broken fibers in glass-fiber-reinforced epoxy matrix composites reveal different kinds of highly oriented patches at the circumambience of broken fibers, whereas the bulk of the matrix has been observed to be largely isotropic. These patches are interpreted to correlated areas where the stress gradients of the matrix are formed after fiber breaking, but the underlying cause for the orientation is still unknown. The authors have modified an embedded cell model to explain the experimental phenomena. The finite element simulation indicates that the surfaces around broken fibers display a change from an extension micromorphology to a mixed tension and shear micromorphology with the increase of applied strain.

Gelatin multilayer assembled on the poly(L-lactic acid) surface for better cytocompatibility

Gelatin multilayers were assembled on PLLA substrate at pH 3, 5, and 7, which was below, around, and above the isoelectric point of the amphoteric polymer, using the layer-by-layer assembly technique. The multilayer deposition on the PLLA substrate was monitored by X-ray photoelectron spectroscopy (XPS) and water contact angle measurement. The XPS, water contact angle, and atomic force microscopy data indicated that the layer thickness, surface hydrophicity, and surface morphology of the gelatin multilayers assembled strongly depended on the pH at which the layers were deposited

Synthesis of novel star-like hyperbranched polymers with poly(amido amine) core and poly(L-lysine) shell

Hyperbranched poly(amido amine)s containing vinyl and hydroxyl groups were successfully synthesized via Michael addition polymerization of triacrylamide (TT) and 3-amino-1,2-propanediol (APD) with equal molar ratio in feed. H-1, C-13 and HSQC NMR techniques were used to clarify the structure of hyperbranched polymers and polymerization mechanism.

Synthesis and micellization of star-like hyperbranched polymer with poly(ethylene oxide) and Poly(epsilon-caprolactone) arms

Novel star-like hyperbranched polymers with amphiphilic arms were synthesized via three steps. Hyperbranched poly(amido amine)s containing secondary amine and hydroxyl groups were successfully synthesized via Michael addition polymerization of triacrylamide (TT) and 3-amino-1,2-propanediol (APD) with feed molar ratio of 1:2. H-1, C-13, and HSQC NMR techniques were used to clarify polymerization mechanism and the structures of the resultant hyperbranched polymers

Biodegradation of poly(L-lactide-co-glycolide) tube stents in bile

The objective of this study was to evaluate degradation behavior and the feasibility of biodegradable polymeric stents in common bile duct (CBD) repair and reconstruction. Various molar ratios of lactide (LA) and glycolide (GA) in poly(L-lactide-co-glycolide) (PLGA) were synthesized and processed into a circular tubing of similar to 10.0 mm outer diameter and a wall thickness of about 2.0 mm.

Two novel triphenylamine-substituted poly(p-phenylenevinylene) derivatives: synthesis, photo- and electroluminescent properties

Two novel triphenylamine-substituted poly(p-phenylenevinylene) derivatives, P1 and P2, have been successfully synthesized through the Witting-Horner reaction. The structures and properties of the monomers and the resulting polymers were characterized by using H-1 NMR, FT-IR, GPC, TGA, UV-vis absorption spectroscopy, cyclic voltammetry (CV) and electroluminescence (EL) spectroscopy

Effect of core structure on the fluorescence properties of hyperbranched poly(phenylene sulfide)

We functionalize the focal group of hyperbranched poly(phenylene sulfide) (HPPS) with benzyl, phenyl, and naphthyl group, respectively. DSC analysis shows that T-g of HPPS is increased from 55 to 93 degrees C by functionalization of the focal group with a conjugated naphthyl group. The fluorescence properties of the three core-functionalized HPPS' are studied under the comparison with the original HPPS.

Hollow fibers of yttria-stabilized zirconia (8YSZ) prepared by calcination of electrospun composite fibers

8YSZ fibers were synthesized by calcination of PVP/zirconium oxychloride/yttrium nitrate composite fibers (PVP-Precursor) obtained by electrospinning. Scanning electron microscopy (SEM) indicated that the 8YSZ fibers are hollow and the gas released during organic binder decomposition resulted in the formation of hollow center in fibers

Sulfonated poly(ether ether ketone)/clay-SO3H hybrid proton exchange membranes for direct methanol fuel cells Journal of Power Sources

A new type of sulfonated clay (clay-SO3H) was prepared by the ion exchange method with the sulfanilic acid as the surfactant agent. The grafted amount of sulfanilic acid in clay-SO3H was 51.8 mequiv. (100 g)(-1), which was measured by thermogravimetric analysis (TGA). Sulfonated poly(ether ether ketone) (SPEEK)/clay-SO3H hybrid membranes which composed of SPEEK and different weight contents of clay-SO3H, were prepared by a solution casting and evaporation method. For comparison, the SPEEK/clay hybrid membranes were produced with the same method.

Sulfonated poly(ether ether ketone)/aminopropyltriethoxysilane/phosphotungstic acid hybrid membranes with non-covalent bond: Characterization, thermal stability, and proton conductivity

Sulfonated poly(ether ether ketone) (SPEEK) and aminopropyltriethoxysilane (KH550) hybrid membranes doped with different weight ratio of phosphotungstic acid (PWA) were prepared by the casting procedure, as well as PWA as a catalyst for sol-gel process of KH550. The chemical structures of hybrid membranes were characterized by energy dispersive X-ray spectrometry (EDX) and Fourier transform infrared spectroscopy (FTIR). The morphology of hybrid membranes was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results had proved the uniform and homogeneous distribution of KH550 and PWA in these hybrid membranes.

Biodegradable Interpolyelectrolyte Complexes Based on Methoxy Poly(ethylene glycol)-b-poly(alpha,L-glutamic acid) and Chitosan

We synthesized methoxy poly(ethylene glycol)-b-poly(alpha,L-glutamic acid) (mPEGGA) diblock copolymer by ring-opening polymerization of N-carboxy anhydride of gamma-benzyl-L-glutamate (NCA) using amino-terminated methoxy polyethylene glycol (mPEG) as macroinitiator. Polyelectrolyte complexation between mPEGGA as neutral-block-polyanion and chitosan (CS) as polycation has been scrutinized in aqueous solution as well as in the solid state.

Multilayer structured carbon nanotubes/poly-L-lysine/laccase composite cathode for glucose/O-2 biofuel cell

Multilayer film of laccase, poly-L-lysine (PLL) and multi-walled carbon nanotubes (MWNTs) were prepared by a layer-by-layer self-assembly technique. The results of the UV-vis spectroscopy and scanning electron microscopy studies demonstrated a uniform growth of the multilayer. The catalytic behavior of the modified electrode was investigated. The (MWNTs/PLL/laccase)(n) multilayer modified electrode catalyzed four-electron reduction of O-2 to water, without any mediator.

Facile synthesis of poly(o-phenylenediamine) microfibrils using cupric sulfate as the oxidant

A rapid, templateless, surfactantless approach is proposed to prepare microfibrils by simply mixing of aqueous cupric sulfate and o-phenylenediamine (oPD) solutions at room temperature. The as-prepared poly(o-phenylenediamine) (PoPD) microfibrils have been characterized by optical microscope, transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis) and X-ray diffraction (XRD).

Properties of poly(sodium 4-styrenesulfonate)-ionic liquid composite film and its application in the determination of trace metals combined with bismuth film electrode

A new kind of bismuth film modified electrode to sensitively detect trace metal ions based on incorporating highly conductive ionic liquids 1-butyl-3-methyl-imidazolium hexafluorophosphate (BMIMPF6) in solid matrices at glassy carbon (GC) was investigated. Poly(sodium 4-styrenesulfonate) (PSS), silica, and Nafion were selected as the solid matrices. The electrochemical properties of the mixed films modified GC were evaluated. The electron transfer rate of Fe(CN)(6)(4-)/Fe(CN)(6)(3-) can be effectively improved at the PSS-BMIMPF6 modified GC.

Thermoplastic Elastomers Based on Compatibilized Poly(butylene terephthalate) Blends: Effect of Functional Groups and Dynamic Curing

Two sets of graft copolymers were prepared by grafting glycidyl methacrylate (GMA) or ally] (3-isocyanate-4-tolyl) carbamate (TAI) onto ethylene/propylene/diene terpolymer (EPDM) in an internal mixer. These graft copolymers were used as the compatibilizer to prepare the thermoplastic elastomers (TPEs) containing 50 wt%, of poly(butylene terephthalate), PBT, 30 wt% of compatibilizer, and 20 wt% of nitrile-butadiene rubber, NBR. The indirect, two-step mixer process was chosen for dynamic curing.