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A series of cerium dioxide (CeO 2 )/polyimide (PI) nanocomposites were successfully prepared from Ce(Phen) 3 and polyamic acid (PAA) via the solution direct-dispersing method, followed by a step thermal imidization process. TGA and XPS studies showed that the cerium complex decomposed to form CeO 2 during the thermal imidization process at 300°C. SEM observation showed that...
Submicron polystyrene (PS) fibers were prepared by electrospinning of an aqueous dispersion of PS latex and a small amount of poly(vinyl alcohol) (PVA) and subsequent extraction by water. Depending on particle size, surfactant, ratio of PS:PVA, and applied voltage fibers of different morphology and water stability were obtained. Analysis of latex fibers by TEM revealed hexagonal packaging of particles...
Mesostructurally ordered inorganic–organic hybrid composite materials were successfully synthesized by utilizing a low-molecular-weight amphiphilic polyethylene-block-poly(ethylene oxide) (PE–PEO) diblock copolymer as the directing agent. The hybrid composites were formed via the sol–gel reaction of inorganic precursor tetraethoxysilane (TEOS) in an acidic ethanol/water solution with various amounts...
Polypyrrole/sulfonated polyaniline (PPY/SPANI) composite films have been prepared by direct electrochemical polymerization of pyrrole in an aqueous solution of SPANI. Spectroscopic results demonstrated that the polyanion, SPANI, was incorporated into the PPY matrix as a dopant. The composite films exhibited a higher thermal stability than that of pure PPY. Scanning electron microscopic images revealed...
Polymers are becoming increasingly used in aerospace structural applications, where they experience complex, non-static loads. Correspondingly, the mechanical properties at high strain rates are of increasing importance in these applications. This paper presents an investigation of the properties of Dupont 9B polytetrafluoroethylene (PTFE) across strain rates from 10 −3 to 10 5 s ...
Concentration dependence of the storage modulus, E′, was investigated for polyvinylacetate (PVAc) filled with hydroxyapatite (HAP) nanoparticles. The filler volume fraction, v f , varied from 0 to 0.05 and the E′ and loss tangent, tanδ, were measured below neat matrix T g at −40°C and above neat matrix T g at +50°C at 1Hz. The T g determined as the position of the maximum...
Rheological properties of aqueous solutions and hydrogels formed by an amphiphilic star block copolymer, poly(acrylic acid)-block-polystyrene (PAA 54 -b-PS 6 ) 4 , were investigated as a function of the polymer concentration (C p ), temperature, and added salt concentration. The water-soluble polymer synthesised by atom transfer radical polymerization (ATRP) was found...
The miscibility and molecular dynamics of nanostructured maleated polypropylene (mPP)/polycarbonate (PC) blends prepared by in situ polymerization of macrocyclic carbonates with polypropylene modified with 0.5wt% of maleic anhydride-reactive groups were investigated over a wide range of frequencies (10 −2 –0.5×10 7 Hz) at different constant temperatures using broadband dielectric spectroscopy...
A series of 1,4-distyrylbenzene derivatives containing 1,1-dicyanovinyl moieties were designed as poly-p-phenylenevinylene analogs to obtain the red electroluminescence assisted by the computational results. Based on the subsequent synthesis and optical studies, the present work indicated that introduction of 1,1-dicyano group as electron receptor in PPV skeleton could shift the electroluminescence...
A family of copolymers of N,N-dimethylacrylamide containing blocked isocyanate functionalities is presented. The copolymers were characterized by DSC, GPC and 1 H NMR. Calorimetric analysis showed for any composition broad endothermal phenomena followed by a stronger exothermal peak, which can be attributed, respectively, to the deblocking and subsequent reaction of generated NCO groups.Characterization...
High-resolution magnetic resonance imaging (MRI) has been used, for the first time, to measure fluorine concentration profiles with a high spatial resolution (5μm) along the full film depth of fluorinated polyurethane films. The MRI fluorine profiles were consistent with the results obtained by X-ray photoelectron spectroscopy (XPS) in combination with microtoming. MRI is a nondestructive and potentially...
The conformational characteristics of poly(ethylene oxide) (PEO) in methanol at 25°C were investigated by static light scattering and viscometry for high molar mass (M w ) PEO fractions covering M w =3.42×10 5 –5.05×10 6 gmol −1 . No trace of downturn in the plot of angular dependence of Kc/R θ at low angle was found. Experimental scaling laws for the...
Ternary blends composed of a liquid crystalline polymer (LCP), nano-SiO 2 and polysulfone (PSF) were prepared by melt blending. Very long and perfectly oriented LCP fibrils were in situ formed in capillary flows by adding 5vol% of nano-SiO 2 to binary PSF/LCP blend. Dynamic rheology analysis indicated that the sharp increase of elasticity was caused by higher content of nano-SiO ...
Hydrogels of poly(N-isopropylacrylamide) co-polymerized with acrylic acid [P(NIPAAm-co-AAc)] were synthesized with cross-linking degrees of 2–7% using (N,N′-methylenebisacrylamide). SEM micrographs revealed that the morphology of dry hydrogels changes from interconnected spherical pores to channel-like pores, with the change in the cross-linking degrees from 3 to 5%. The change in morphology is associated...
We studied the effect of solvent selectivity on the closed-loop phase behavior of a polystyrene-block-poly(n-pentyl methacrylate) copolymer. It was found that the lower disorder-to-order transition temperature (LDOT) and upper order-to-disorder transition temperature (UODT) consisting of the closed-loop were very sensitive to the selectivity of the solvent. With the addition of very small amounts...
The glass transitions of acrylonitrile–butadiene rubber (NBR)/organoclay nanocomposites with various silicate contents were investigated using positron annihilation lifetime spectroscopy (PALS). The nanocomposites were prepared through melt intercalation of NBR with various concentrations of organoclay (OC30B) modified with the organic modifier, methyl tallow bis(2-hydroxyethyl) quaternary ammonium...
The dynamics of phase separated micellar solutions of randomly sulphonated polystyrene ionomers in toluene were examined with neutron spin echo spectroscopy (NSE). The correlation functions demonstrated single exponential decays with a constant background offset. The relaxation rate (Γ) of the ionomer micelles at small length scales in the q range 0.075–0.16Å −1 was diffusive (Γ∼q 2 ...
In order to complete a preliminary work about the direct fluorination of poly(p-phenylene) (PPP), the main parameters of the process were investigated. The molecular (chain length and crystallinity) and morphological effects (B.E.T. surface, granulometry) were studied. So, two new starting samples were studied in addition to PPP synthesized by the Kovacic's method (i) a commercial PPP (Polysciences)...
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