Materials Literature
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We examined the free surface of a banded spherulite of poly (vinylidene fluoride) (PVDF) by atomic force microscopy. The directions of the slope of multilayer terraces of lamellar crystals are retained in each half of a banded spherulite; this evidence confirms the macroscopic selection of one-handedness in the format…
Direct evidence that nuclei are formed during the induction period of crystallization is obtained for the first time by means of small-angle X-ray scattering (SAXS). Polyethylene (PE) was used as a model crystalline polymer. The nucleating agent was mixed with PE in order to increase the scattering intensity I x from…
Abstract A new type of hyperbranched polysilazane containing iron (PSZI) compound was synthesized by the polycondensation of silazane lithium salts with FeCl 3 , and the structure of the PSZIs was investigated by IR, NMR and elemental analyses. The PSZIs were pyrolyzed under nitrogen, argon or NH 3 , and magnetic cera…
Copolymers (2‐HAOF), synthesized by the condensation of and H2N(O)CC(O)NH2 with CH2O in the presence of acid catalyst, proved to be selective chelating ion‐exchange copolymers for certain metals. The chelating ion‐exchange properties of this copolymer were studied for Cu(II), Ni(II), Co(II), Zn(II), Fe(III), Cd(II) an…
Organic phosphates used as nucleating agents can remarkably promote the stiffness and crystallization rate of polypropylene homopolymer and ethylene–propylene copolymer. In this article, the nucleating activity of 2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphoric acid and its derivatives for isotactic polypropyle…
Corrugated crystal morphologies of poly(ethylene succinate) (PESU) with a bird-wing shape grew from the thin-film melt with the film thickness less than 1 μm. The center of the bird-wing-shaped crystal consisted of a lozenge crystal. Corrugated steps were observed in the direction of the short axis of the lozenge crys…
The molecular weight (MW) dependence of the primary nucleation rate (I) was studied for poly(ethylene succinate). The primary nucleation rate was measured in a wide range of temperatures. It has a bell shape with a maximum nucleation rate (I max ) that showed a remarkable MW dependence. I max decreased first with MW t…
Although observations of molecular processes in the formation of primary nuclei prior to actual crystallization are beyond the detection limits of current instrumentation, we attempted to probe the nature of primary nuclei in sheared isotactic polypropylene (iPP) polymer melt. In situ rheo-SAXS (small-angle X-ray scat…
Optimum conditions for melt crystallization without thermal degradation for atactic poly(vinyl alcohol) (PVA) were found for the first time. Thermal degradation of PVA in the melt has been too serious to permit crystallization from the melt. However, it was found that thermal degradation can be suppressed by selecting…
Abstract The annealing at 373 K of ultrastrong, gel‐spun polyethylene (PE) has been studied. At this temperature, the fibers show no significant shrinkage. Still, a significant decrease in the mechanical properties is observed. The fibers have been analyzed with differential scanning calorimetry (DSC), temperature‐mod…
Abstract Silicic acid produced from sodium metasilicate hydrate and metallocene polyethylene–octene elastomer (POE) were chosen as the ceramic precursor and the continuous phase, respectively, for preparation of new hybrids by an in situ sol–gel process. To obtain a better hybrid, the acrylic acid‐grafted polyethylene…
Antimony silicates doped with a metal, (M)x,ySb2-xSi2-yO7 (M=W, Ti, Nb), were studied for the removal of the key radionuclides 85Sr, 134Cs, and 57Co from nuclear waste solutions. Emphasis was given to the removal of radionuclides from acidic effluents for which no efficient commercial exchangers are available. Initial…
Abstract The preparation of microcellular polystyrene (PS), lightly sulfonated polystyrene (SPS), zinc‐neutralized lightly sulfonated polystyrene (ZnSPS), and blends of PS/SPS and PS/ZnSPS via supercritical CO 2 was carried out with the pressure‐quench process. Both higher foaming temperature and lower pressure result…
Polymer crystallization from a uniaxially stretched amorphous state was investigated by molecular dynamics simulation using a realistic molecular model of poly(ethylene). Simulations for crystallization were performed at temperatures between 280 and 350 K. Structure formations to crystalline states having lower symmet…
Molecular weight (M) dependence of the equilibrium melting temperature of isotactic polypropylene (iPP) with high tacticity ([mmmm]=99.6%) was studied. Four fractionated iPPs with M n=23×103, 64×103, 94×103, and 263×103 were used. was obtained by using an improved method based on the Gibbs–Thomson plot proposed in pre…
The present study focuses on the creation of a framework and methodology to span three orders of magnitude in scale with interconnected models that relate performance of single wall carbon nanotubes (SWCN) at the nanometer scale to a nanoarray, nanowire, and microfiber with self-similar geometries. The geometry chosen…
Abstract The variations in the molecular orientation of uniaxially drawn rigid‐rod polyimide films were systematically characterized in all three dimensions with polarized attenuated total reflection/Fourier transform infrared spectroscopy. The second‐order orientation coefficients were directly deduced from the aniso…
An aluminium single crystal with [110] initially parallel to the tensile axis and (1&1macr;1) initially parallel to the front face of the crystal was elongated by 30%. Macroscopic deformation bands were visible on the broad face of the crystal after deformation. To explore the deformation–band characteristics, crystal…
This paper reports the formation of novel hydrogen-bonded assemblies 1(3).CA obtained upon mixing cyanuric acid (CA) with melamine derivatives 1, in which two of the three possible H-bonding arrays have been blocked. The four components are held together by 9 hydrogen bonds and form a rigid planar structure in which a…
10.1021/ma025662i