Materials Literature
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Direct measurements of the velocity of a high-molecular-weight polydimethylsiloxane melt in the immediate vicinity of a solid wall (100 nm from the interface) have been conducted, using a novel optical technique based on evanescent wave induced fluorescence and pattern photobleaching. On silica, quite distinct behavio…
At H2 pressures of up to 2 kbar, new ternary transition metal hydride complexes can be synthesized in which the transition metal has the same high oxidation state as in the corresponding ternary halides. In K2PtH6, which was prepared by this method, the complex [PtH6]2− building unit 1 was observed.
We describe three sets of experiments on suspensions of 'hard-sphere' colloids. Suspensions of equal-sized particles exhibit the hard-sphere freezing and glass transitions. Mixtures of spheres of two different sizes can form the ordered binary crystals AB 2 and AB 13 . The addition of non-adsorbing polymer to a one-co…
Liquid crystalline polymers in nematic solvents are studied theoretically. Three different scenarios are discussed: (i) confined polymers; (ii) grafted polymers and (iii) double brushes. The competition between nematic distortion, chain elasticity, excluded volume and nematic anchoring enables these systems to exhibit…
A structural study of liquid sulphur has been performed around the polymer transition as a function of temperature. Below this transition, the liquid is shown to mainly consist of S8 molecular units. Above the transition, small-angle scattering data can be used to evidence the presence of large polymerized units.
Abstract Possible changes in the structure and properties of maleated polyethylene (HDPE–MA) at different degrees of grafting (D.G.) were examined. At the level of 1.6 maleic anhydride (MA)/100 ethylene units E, 70–80% of crystallinity of the parent PE was retained (DSC and WAXD). Both melting temperature and crystall…
Abstract Bisphenol A polycarbonate (PC)–poly‐ε‐caprolactone (PCL) blends have been prepared by melt mixing in the presence of different catalysts using a Brabender plastograph and single‐screw extruder at 240–260°C. Increased crystallizability [detected by differential scanning calorimetry (DSC)] of the PC component w…
Abstract The tensile properties of polypropylene fibers, produced in a short‐spin line, are correlated with the parameters of the three processing stages (spinning, drawing, and annealing), and with the molecular weight distribution. In general, tensile stiffness and strength increase with increasing molecular orienta…
Concerns over the safety of the continued use of aging transport aircraft have been voiced in the industry. A key component in the structural integrity of aging aircraft is the damage tolerance of fuselage structural repairs. The investigation focuses on the analysis and testing of contemporary repair methods and deve…
Participation of the oxygen atoms of the siloxane framework of ligand 1, and not only the terminal hydroxyl groups, may be required for the coordinative saturation of a metal center. This surprising conclusion was drawn from the X-ray structure analysis of the first rare earth metal complex with this type of ligand. C…
We have discovered a new type of angular dependent magnetotransport which permits the measurement of the Fermi surface parameters of quasi-one-dimensional metals. Resistance measurements of (TMTSF${)}_{2}$${\mathrm{ClO}}_{4}$ in the c (least conducting) direction show pronounced resonances when the field is rotated in…
When two similar small particles are attached to a liquid interface they attract each other due to a lateral capillary force. This force appears because the gravitational potential energy of the floating particles decreases when they are approaching each other. This force is proportional to R 6 (R is the particle radi…
Benzene wins the battle for aromaticity against [18]annulene. The first fully conjugated, benzene-containing porphyrin analogue 1 is not an 18 π aromatic system; only the tautomer with the intact arene is observed. This compound is synthesized from the corresponding tripyrranedicarboxylic acid and isophthalaldehyde an…
Oxidation and reduction rates are increased when the photocatalyst TiO 2 is doped with metal ions. The photochemical oxidation of CHCl 3 and the photochemical reduction of CCl 4 were examined in the presence of 21 different doped TiO 2 catalysts. Dopant metal ions with closed shells were found to have little effect on…
The latex particles composed of poly(styrene/N-isopropylacrylamide/glycidyl methacrylate) [P(St/NIPAM/GMA)] and poly(styrene/N-isopropylacrylamide/methacrylic acid) [P(St/NIPAM/MAA)] were prepared by emulsifier-free emulsion polymerization. These latex particles with submicrometer size showed the thermosensitivity ori…
A new carburizing stainless steel alloy that resists corrosion, heat, and fatigue has been developed for bearing and gear applications. Pyrowear 675 Stainless alloy is vacuum induction melted and vacuum arc remelted (VIM/VAR) for aircraft-quality cleanliness. Test results show that it has corrosion resistance similar…
(β-polytype of InSe single crystals of p- and n-type are intercalated with Ba and Li by electrochemical process. This compound shows to be a good host for the insertion of Ba or Li atours at room temperature. The temperature dependence of the resistivity in the temperature range 4.2 < T < 300 K and the magnetoresistan…
The processes of radiation damage, from initial defect production to microstructure evolution, occur over a wide spectrum of time and size scales. An understanding of the fundamental aspects of these processes requires a spectrum of theoretical models, each applicable in its own time and distance scales. As elements o…
Abstract In this work we present the optimization of the processing conditions for PVC plastisol rotational molding. The effects of oven temperature, processing time, rotational, speed and amount of plastisol over the degree of curing, physical appearance, and mechanical properties of the molded articles were studied.…
Abstract Corrugated mats of palygorskite occurring in regolith overlying a fissured limestone were examined by X-ray diffraction, infrared spectroscopy, and electron optical techniques after heating at 50°C intervals to 700°C. Palygorskite ‘anhydride’ formed at 400°C and sillimanite formed at 500°C. The palygorskite i…