Materials Literature
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The structure, properties, and uses of poly(dimethylsiloxane) are surveyed in relation to its surface activity, with emphasis on the structural basis of this activity: the low intermolecular forces between methyl groups and the unique flexibility of the siloxane backbone. These basic attributes are used to explain the…
The use of brittle polymers, such as polyvinyl chloride (PVC) and polystyrene (PS), was limited prior to the development of rubber-toughened polymers in the 1930s and 1940s. PVC has been toughened by the addition of small amounts of acrylonitrile rubber (NBR) and other elastomeric materials. Over 1.5 million tons of r…
Gels are swollen networks possessing both the cohesive properties of solids and the diffusive transport properties of liquids. Elastically, they tend to be soft, and osmotically they are highly reactive. Gels based on water incorporate water's unique properties, in particular, the facility for ionization that an aqueo…
Abstract About 65 diverse phenyl benzoates incorporating a trans ‐1,4‐disubstituted cyclohexane ring and at least one lateral substituent have been synthesised. The dependence of the liquid‐crystal transition temperatures of these materials on various lateral substituents (F, Cl, CN, and Br) in different positions of…
A new activating reagent for amide condensation [(1,2,3-benzotriazine-4-one)-3-yl] diphenyl phosphate (BTDP), was prepared in good yield (88%) by the reaction of 3-hydroxy-1,2,3-benzotriazine-4-one with diphenyl phosphorochloridate in the presence of triethylamine (TEA) in tetrahydrofuran. Benzanilide was readily prep…
Si 3 N 4 test bars containing additions of BN, B 4 C, and C, were hot isostatically pressed in Ta cladding at 1900° and 2050°C to 98.9% to 99.5% theoretical density. Room‐temperature strength data on specimens containing 2 wt% BN and 0.5 wt% C were comparable to data obtained for Si 3 N 4 sintered with Y 2 O 3 , Y 2 O…
Abstract The crystallization of K 2 SO 4 from aqueous solutions of glaserite (a double salt of sodium and potassium sulphate) was investigated in an MSMPR cooling apparatus at 35 °C. The precipitation of K 2 SO 4 at an average purity of 93 wt.% was obtained and the crystallization kinetics were derived from the experi…
The reaction rate of hydrogen isotope exchange between D 2 and H 2 O catalyzed by platinum plate is studied. The exchange reaction is described with the kinetic model which is the modification of that for the exchange reaction catalyzed by alumina-supported platinum catalyst. For the comparison of experimental results…
Diamond layers were grown on SiAlON substrates by hotfilament activated chemical vapour deposition (TA-CVD) using acetone/hydrogen gas mixtures. The acetone concentration and the gas pressure greatly influenced the crystal size and quality of diamond deposited. Increasing the total gas pressure and the acetone concent…
Abstract An electrochemical method for polymerizing pyrrole on a glass fabric without using metal anode to give a polypyrrole/fabric composite is proposed. The glass fabric is precoated with a thin layer of polypyrrole polymerized by use of ferric chloride as oxidizing agent. Morphological change during the polymeriza…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTX-ray powder diffraction at the spin-state transition in N,N'-ethylenebis(3-carboxysalicylaldiminato)cobalt(II) complexesEdgar Koenig, G. Ritter, J. Dengler, P. Thuery, and J. ZarembowitchCite this: Inorg. Chem. 1989, 28, 9, 1757–1759Publication Date (Print):May 1, 1989Publi…
The chemical steps of the Si and SiC deposition from DCS/H2 and MTS/H2 respectively, are approached on the basis of a calculation of the homogeneous equilibria. SiCl2 appears to be a major intermediate species in both cases. Supersaturation is found to be very high particularly at low temperature. A calculation of the…
New phenomenology of the chiral nematic (N), smectic-A (A), ferroelectric smectic-C (C) point (NAC) is reported in a binary mixture of two chiral components. We find a tricritical point on the AC phase-transition line which is displaced from the NAC point, and an NA line which is first order. At the NAC point all thre…
Abstract The morphology of polyamide 12 and polyether block amide blends was investigated by electron microscopy and dynamic mechanical techniques. The blends are not miscible, and phase segregation is observed. In each phase, the lamellar structure of the pure components is observed. The stability of these micro phas…
Abstract The IR emission and the corresponding low energy excitation spectra of the wide band gap semimagnetic semiconductors Zn 1− x Mn x Te, Cd 1− x Mn x Te, Zn 1− x Mn x Se, Cd 1− x Mn x Se, Zn 1− x Mn x S, and Cd 1− x Mn x S are critically discussed in the light of the models proposed until now. The similar shape…
The pE194 replication origin was localized to a 265-base-pair interval by analyzing the ability of purified pE194 restriction fragments to direct replication of heterologous plasmids. Replication was dependent upon RepF protein supplied in trans. The origin region contained a GC-rich dyad symmetry which may serve as t…
A measuring procedure has been developed to determine the hysteresis loss as function of the magnetizing frequency. It was applied to single crystal frames of iron-silicon and tape wound cores of that alloy and metallic glasses. Actually the hysteresis loss energy is frequency dependent and to an extent that must not…
The magnetic characteristics of two representatives of martensitic and one of ferritic stainless steels, i.e. SUS 403, TAF, and SUS 405, were investigated in connection with development of high-temperature and nuclear resistive sensors. The test pieces were machined out from rod materials and heat-treated in an argon…
Sterilization of bioreactor media, to destroy viability of the indigenous microbial population, is normally accomplished by autoclaving, or heating with pressurized steam. However, simultaneous chemical changes in media can also be expected to result from the high temperatures. A kinetic procedure involving on-line co…
Oligomerization of mono- and oligosaccharide units can be an interesting methodology for synthesis of homooligosaccharides and oligosaccharides having repeating units, respectively. Recently, chitooligosaccharides, especially the hexamer, were shown to have an antitumor effect,2 suppress metastasis3 and protect agains…