Materials Literature
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Cellulose, either as a major component in wood or as the prime textile fiber cotton, is most frequently implicated in fire, causing injuries and fatalities [1]. When ignited, cellulose undergoes thermal degradation, form-ing combustible volatile compounds which become involved in the propaga-tion of fire. Fortunately…
Thermoelectric power, electrical resistivity, and magnetization experiments, performed in the paramagnetic phase of ${\mathrm{La}}_{2/3}$${\mathrm{Ca}}_{1/3}$${\mathrm{MnO}}_{3}$, provide evidence for polaron-dominated conduction in colossal magnetoresistance materials. At high temperatures, a large, nearly-field-inde…
Large-amplitude, low-frequency electric fields can be used to burn spectral holes in the dielectric response of supercooled propylene carbonate and glycerol. This ability to selectively modify the dielectric response establishes that the non-Debye behavior results from a distribution of relaxation times. Refilling of…
Reaction mechanisms for the hydrothermal synthesis of barium titanate are evaluated. Feedstocks of barium hydroxide octahydrate and anatase titania are reacted for varying durations (1–72 h) to provide intermediate‐stage samples for characterization by transmission electron microscopy/ energy‐dispersive spectroscopy (…
Abstract In order to expand the range of high‐quality nanosized semiconductor materials that can be obtained as quantum dots through a wet chemical route a series of oxidize‐stable CdTe nanoclusters with narrow size distributions and extremely small particle sizes ranging from 1.3 to 2.4 nm has been prepared in aqueou…
Alloys protected from corrosion by a chromia scale and ‐based perovskites are used as materials for the interconnect of solid oxide fuel cells (SOFCs). The chromium vaporization of these materials was studied by thermochemical modeling. Partial pressures of the vaporizing species were determined for different and conc…
Abstract The effect of droplet size on the rheological behavior of water‐in‐oil and oil‐in‐water emulsions was investigated using a controlled‐stress rheometer. Results indicate that the droplet size has a dramatic influence on emulsion rheology. Fine emulsions (water‐in‐oil or oil‐in‐water) have much higher viscositi…
Electrochemical capacitors, also called supercapacitors, are unique devices exhibiting 20 to 200 times greater capacitance than conventional capacitors. The large capacitance exhibited by these systems has been demonstrated to arise from a combination of the double‐layer capacitance and pseudocapacitance associated wi…
Using XPS and x-ray-excited Auger electron spectroscopy (XAES), we have studied the variation in surface composition of CuO and Cu2O with a variety of high-vacuum treatments, including vacuum annealing, oxidation and hydrogen reduction. Prolonged annealing of CuO results in the formation of a thick layer of Cu2O at th…
Over the past several years, cerium oxide and CeO2-containing materials have come under intense scrutiny as catalysts and as structural and electronic promoters of heterogeneous catalytic reactions. Recent developments regarding the characterization of ceria and CeO2-containing catalysts are critically reviewed with a…
A new bismaleimide (BMI) resin system, designated 4504, with excellent heat resistance and good mechanical properties for advanced composites was developed. The 4504 resin was made up of 4,4′-bismaleimidodiphenyl methane, diallyl bisphenol A, and desirable catalysts. The reactivity of 4504 was investigated by gel char…
Changes of reaction variables upon the reaction of jute fiber with acrylonitrile, like concentration of sodium hydroxide, reaction time, and reaction temperature, were studied in the present work. Benzene and dioxane were used as diluents for acrylonitrile and reactions were conducted in their presence in different am…
The influences of processing variables on the mechanical properties of general grade poly-propylene prepared by oscillating packing injection molding under low pressure were reported. The density as a function of oscillating holding pressure was measured using density gradient columns. The existence of spherulites and…
X-Ray photoelectron spectroscopy (XPS) and theoretical calculations show that under certain conditions inner valence molecular orbitals (IVMOs) can form within a rather broad binding energy range (15 eV to 50 eV) in compounds of many elements of the Periodic Table. This results in the appearance of a fine structure in…
The dynamic mechanical properties of both homopolypropylene (PPVC)/Maleated Poly-propylene (PP-g-MA) and ethylene-propylene block copolymer (PPSC)/Maleated Poly-propylene (PP-g-MA) blends have been studied by using a dynamic mechanical thermal analyzer (PL-DMTA MKII) over a wide temperature range, covering a frequency…
We investigated possible physical and chemical changes in inert polymers by means of mechanical milling. No chemical changes were observed. However, in polystyrene we found two glass temperatures after milling, in contrast to one glass temperature in the original material. Under certain conditions crystalline polyethy…
It has become possible in recent years to synthesize new materials under controlled conditions with constituent structures on a nanometer size scale (below 100 nm). These novel nanophase materials have grain-size dependent mechanical properties that are significantly different than those of their coarser-grained count…
A newly synthetic method has been developed for the preparation of block copoly(urethaneimide) (PUI). The copolymer was yielded from the direct reaction of the prepolyurethane terminated with isocyanate and the prepolyimide terminated with anhydride. The latter is prepared by reacting an excess amount of pyromellic di…
Polyurethanes were synthesized from polyester and butanediol with three different diisocyanates, i.e., 4,4´-diphenylmethane diisocyanate (MDI), m-xylene diisocyanate (XDI), and 2,4-toluene diiscynate (TDI). The effect of chemical structures of diisocyate compounds on the degree of crystallinity and the thermal stabili…
The influence of external factors on the formation of various polymorphic modifications of poly(vinylidene fluoride) (PVDF) and the copolymers and blends based on it is examined. It is shown that the formation of a particular conformational structure of the PVDF chains may be controlled by regulating, for example, the…