Materials Literature
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Ring frame process parameters, namely spindle speed, top roller pressure and traveller mass, have been optimized using three-variable Box and Behnken design to achieve better yarn quality and production. It is observed that 15000 rpm spindle speed with top roller pressure of 2.5 kg/cm2 and traveller mass of 50 ISO No.…
Curved-face growth of NaNO 3 crystals under the action of the (NH 4 ) 2 Mo 2 O 7 impurity is studied experimentally and possible causes of face bending are analyzed. Selective impurity adsorption on the basal pinacoid results in growth of platelike crystals with spherically bent faces. Growth-rate measurements show th…
The goal of the work presented here was to synthesize multiblock copolymers based on transesterification polycondensation of end group functionalized PEEK with PSU oligomers in the melt. In the synthesis of PEEK oligomers by nucleophilic aromatic substitution cyclization occured observed by decreasing amount of end gr…
A novel vibrational spectroscopic approach has been developed to better understand the structure activity relationship (SAR) component of the drug discovery effort. First, vibrational spectroscopy has been developed as a tool for the identification of molecular subcomponents within a compound series, which play an act…
A polysilane with a C-to-Si ratio of 6.0 was pyrolysed to produce an amorphous matrix (source powder), which was heated further to obtain different products. These polysilane-derived samples were studied using X-ray diffraction, Raman spectroscopy, solid-state magic-angle-spinning nuclear magnetic resonance and transm…
The reaction of antimony(III) oxide with ethylamine, in molar ratios from 1:1 to 1:10, in concentrated hydrobromic acid leads to the formation of one product - bis(ethylammonium) pentabromoantimonate( III). The structure of (C 2 H 5 NH 3 ) 2 [SbBr 5 ] was determined at 298 and 90 K, below and above the phase transitio…
The spin-reorientation transition of layered perovskite oxide SrNdFeO 4 has been investigated through powder x-ray and neutron diffraction, magnetic susceptibility, specific heat and 57 Fe Mössbauer spectrum measurements. This oxide presents tetragonal symmetry (space group: I 4/ mmm ) and the FeO 6 octahedron is axia…
The influence of the number of stitches in the seam on the joined places of car seat coverings was investigated. The properties of the fabric in seamless places were examined as well. Fabric samples include: technical fabrics, nonwoven materials, knitted fabrics, artificial leather that were cut from sewn seat covers…
In this work, we describe how the anomalous diffusivity is related to the structural anomalies. For this purpose, we study how the thermodynamics and the dynamics of low-temperature water are affected by the decrease of the density.
Abstract A comparative study of the structure and properties of two‐phase blends of polyamide 6 (PA6) and low‐density polyethylene (LDPE) modified in the course of reactive extrusion, by grafting of itaconic acid (IA) without neutralization of carboxyl groups (LDPE‐ g ‐IA) and with neutralized carboxyl groups (LDPE‐ g…
The microstructure of a series of experimental high chromium, high carbon cast irons was examined by optical and electron microscopy to determine the mechanisms that impart their resistance to wear by impact of reduced iron pellets at 550 ° C. The samples were cast following an experimental design in which the amount…
Stabilization of the unipolar state via the formation of inhomogeneous impurity distribution in crystal bulk is considered. Possible growth of crystals with stable characteristics is demonstrated on triglycine sulfate (TGS) crystals with a regular inhomogeneous impurity distribution. The properties of TGS crystals wit…
Field emission properties of standalone carbon nanotubes have been investigated in terms of the capped and open-ended tip shapes. The capped multiwall nanotube with a tip curvature of ∼2.5 nm is compared with the open-ended single wall nanotube with a diameter of ∼5 nm. These samples have almost the same current-volta…
Abstract The toughness of impact‐modified poly(vinyl chloride) (PVC) compounds was examined by using a modified Charpy test. Increasing impact speed resulted in a quasi‐brittle to ductile transition in all PVC compounds. In the quasi‐brittle region, a PVC of 56,000 M w fractured through a craze‐like damage zone that c…
The calculation method of distributions of minority charge carriers generated in the two-layer semiconductor by a wide electron beam with energies 5 - 30 keV based on using the model of independent sources is described.
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…