Materials Literature
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Tri[(3-chloro-2-hydroxy-1-propoxy)-1-butylene] borate (TChHPB) was obtained as a result of reaction of tri(hydroxybutylene) borate with epichlorohydrin. It was applied in a synthesis of rigid polyurethane-polyisocyanurate (PUR-PIR) foams, as a flame retardant and an agent improving other functional properties. Increas…
Face-to-face bismacrocycles involving porphyrinoid species are still of great interest owing to their versatile properties. Despite the fact that their syntheses generally involve several steps, numerous modifications have been made in their synthetic pathways thus allowing their preparation in gram quantities. Here w…
Abstract End silane functionalized polystyrene and polymethylmethacrylate were prepared through radical chain‐transfer reaction and characterized with gel‐permeation chromatography. The chain‐transfer constants of mercaptopropyltrimethoxysilane for the polymerization of styrene and methylmethacrylate were determined t…
Though the extruder screw speed of melt spinning, the gear pump's gear speed, and the winder's winding speed are the major factors affecting the tensile strength of as-spun fibers and yarn count (denier), no mathematical model has been proposed to describe the cause and effect of these phenomena. In general, chemical…
O estudo do efeito do envelhecimento em artefatos é principalmente importante quanto ao custo e qualidade, tornando o material atrativo ou não para produtos expostos a condições climáticas mais exigentes. Neste trabalho foi estudado o efeito do envelhecimento acelerado em composições vulcanizáveis de borracha natural…
Abstract Correlated quantum‐chemical calculations are applied to analyze the amplitude of the electronic‐transfer integrals that describe charge transport in interacting carbon nanotubes (CNTs) by investigating the influences of: i) the relative positions of the CNTs, ii) the size of the CNTs, and iii) their chemical…
Abstract Crystallization behavior of blends of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and poly(1,2‐propandiolcarbonate) (PR(CO 2 )) has been investigated by polarized light microscopy (PLM). The spherulite growth rates (SGR) of all blends were faster than that of pure PHBV, and the spherulite growth rates…
Abstract The use of boundary‐conforming finite element methods is considered for the solution of surface‐tension‐dominated free‐surface flow problems in three dimensions. This class of method is based upon the use of a moving mesh whose velocity is driven by the motion of the free surface, which is in turn determined…
The clay deposit of Caxambu Hill occurs in a NW/SE oriented graben originated by syntectonic sedimentation during Cenozoic. Four facies were identified (fragmentary, nodular, massive and friable) and their differentiation is related to gravity mass-flow processes. The fragmentary facies is composed of extraclast fragm…
Neste trabalho foi estudada a degradação de alguns dos principais constituintes dos rejeitos plásticos (polietileno de alta densidade (HDPE), polietileno de baixa densidade (LDPE) e polipropileno (PP)), empregando-se um catalisador exausto de unidades de craqueamento de fluidos (FCC) e um catalisador zeolítico (ADZ3)…
Abstract A review of the historical development, manufacture, properties and applications of solvent‐cast cellulose diacetate film.
The one-pot high temperature catalytic polycyclocondensation of diamines and dianhydrides in molten benzoic acid (BA) was studied. Due to specific features of molten BA as a solvent, obtaining new random and alternating copolyimides (CPIs) becomes possible. Several series of CPIs containing the moieties of different d…
Abstract Ultrafine alumina–silica powders with varying composition gradients within the particles have been produced by chemical vapor synthesis in a hot‐wall reactor using the precursors tetraethoxysilane (TEOS) and aluminiumtrisecbutylate (ASB). The surface chemistry at the particle/liquid interface in aqueous dispe…
Mixed ammonia-water vapor postsynthesis treatment provides a simple and convenient method for stabilizing mesostructured silica films. X-ray diffraction, transmission electron microscopy, nitrogen adsorption/desorption, and solid-state NMR (13C, 29Si) were applied to study the effects of mixed ammonia-water vapor at 9…
Charge carriers injected from the electrode and charge carriers generated in the bulk contribute space charge in low density polyethylene (LDPE). However, it is sometimes difficult to separate their contributions. In this paper, a fluorinated ethylene propylene copolymer (FEP) film was used as a blocking layer. It was…
Technical insulators are largely characterised by unipolar ionic flow. The carriers are supplied by injection, or by bulk ionisation, and the charge transport is space charge perturbed. Continuum equations have provided the basis for models of charge flow. First I show the validity of the Deutsch assumption in gases,…
The laboratory implementation of grazing incidence in-plane X-ray diffraction, using an unmodified commercial diffractometer, is described. Low resolution, high intensity measurements are illustrated in the study of the in-plane lattice parameters and texture of a thin polycrystalline ZnO film on glass, the in-plane o…
We investigated the effects of a chemically‐vapor‐deposited mullite coating (∼100 nm) on the oxidation resistance of sintered Si 3 N 4 in air and steam environments. The coating was sacrificially incorporated into the thermally grown oxide (TGO) on Si 3 N 4 during isothermal oxidation in air at 1400°C, leading to sign…
Swelling properties of chitosan-gelatin films cross-linked by sulfate were investigated. Sulfate cross-linked chitosan-gelatin films (SCG) were prepared simply by dipping chitosan-gelatin films into sodium sulfate solution. The swelling behavior of SCG was investigated as a function of pH and ionic strength. Under aci…
Time-resolved luminescence spectra of an exciton-exciton scattering process and an electron–hole plasma (EHP) were measured in ZnO epitaxial thin films by the optical Kerr gate method. At moderate excitation density below critical Mott density, stimulated emission of luminescence due to the exciton–exciton scattering…