Materials Literature
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At high supercoolings, isotactic polystyrene and polybutene-1 have a rounded crystal shape, suggesting kinetic roughening. Still, the growth rates of these polymer crystals show the supercooling dependence derived for nucleation controlled growth. On the other hand, isotactic poly-4-methylpentene-1 1,4 trans-polybutad…
The crystallization behavior of highly purified natural rubber (NR) was investigated by polarized light microscopy. NR was purified by enzymatic deproteinization followed by transesterification to remove nonrubber components present in the rubber. Nucleation rate and growth rate were estimated from a number of spherul…
Polyesteramide resin based on the condensation of hydroxyethylamide derivatives of fatty acids of soybean {N, N′‐bis(2 hydroxyethyl)soybean amide} and various dibasic acid and anhydride were synthesized. Physico‐chemical characteristics and film forming properties of these resins were determined to prove its suitabili…
Abstract In the second study on melt‐miscible syndiotactic polystyrene (sPS) and poly(phenylene oxide) (PPO) blends, the effect of processing conditions on morphology, ultimate tensile properties, and the mode of fracture is reported. Bulk samples of the blends were molded and then crystallized from melt as well as fr…
The crystal structure of the clathrate form of syndiotactic poly( m -methylstyrene) containing carbon disulfide is presented. The structure is characterized by polymer chains in s (2/1)2 helical conformation and CS 2 molecules packed in an orthorhombic unit cell with axes a = 17.8 Å, b = 13.1 Å, and c = 7.8 Å, accordi…
The ordering process of poly(ethylene terephthalate) (PET) from the oriented glassy states during the isothermal annealing process was investigated using real-time X-ray scattering experiments with synchrotron radiation sources. The X-ray scattering intensity of the 001' reflection, which is a measure of the smectic o…
The crystallization kinetics of isotactic polypropylene (iPP) and nucleated iPP with two organic phosphates, sodium salt (NA7) and triglyceride ester (NA8) of 2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphoric acid, were investigated by means of a differential scanning calorimeter under isothermal and nonisotherma…
Effect of the shear flow (γ˙=0.5∼5 s−1) on the nucleation and on the morphology of polyethylene (PE) during crystallization from the melt was studied by means of polarizing optical microscopy and small angle X-ray scattering. In order to analyze the results by the nucleation theory, we observed the effect of shear flo…
In this paper we study a Landau–de Gennes model of a nematic liquid crystal in a model shear flow employing a range of analytical and numerical techniques. We use asymptotic methods and numerical bifurcation theory to provide a comprehensive description of the different in–plane modes that exist in terms of the temper…
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…