Materials Literature
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Homogeneous formulations of diglycidyl ether of bisphenol A (DGEBA) epoxy resin and a commercial diamine that contain liquid rubber, based on an epoxidized vegetable oil and diamine, form two-phase interpenetrating epoxy thermosets. At lower rubber content, the formulations consist of a rigid DGEBA matrix and randomly…
The morphology of multiphase polymeric systems, polymer alloys, blends, and interpenetrating polymer networks depends on kinetics of polymerization and cross-linking (in reactive systems), composition, degree of polymerization and branching, miscibility (defined in terms of equilibrium thermodynamics), dynamics of pha…
Biopolymers (e.g., starch, protein, and cellulose) from various agricultural sources have been investigated for manufacturing biodegradable plastics. Cross-linking of starch and zein mixtures and of soy proteins have shown that the tensile strength and water resistance of the plastics can be increased. Plastics made f…
Formulation of a new approach to the structure of interpenetrating polymer networks (IPNs) is the objective of this review of the authors experimental works. As a whole, IPNs are not thermodynamically equilibrium systems because, in the course of chemical reactions leading to gelation, simultaneous phase separation pr…
The synthesis of nanometer-sized silica particles by the base-catalyzed, controlled hydrolysis of tetraethoxysilane (TEOS) in a nonionic reverse micellar system is described. Spectrofluorometric techniques were used to characterize the reverse micellar solutions. Particle characterization was conducted by transmission…
Polyurethane-poly(vinyl chloride) pseudo-IPN (interpenetrating polymer network) elastomers, polyurethane-poly(vinyl ester) IPN foams, and polyurethane-epoxy-unsaturated polyester two- and three-component IPN foams and elastomers were studied by dynamic mechanical spectroscopy sound absorption (impedance tube technique…
Agricultural feedstocks should be used for the production of materials, especially plastics, and chemicals because of the abundant availability of agricultural feedstocks, the value it would add to the U.S. economy, and the reduction in U.S. trade deficit that could be achieved. However, the use of agricultural feedst…
The control of silica sol coagulation by pH and by addition of simple electrolytes is said to be "anomalous" in that it is not simply predicted by conventional Derjaguin-Landau-Verwey-Overbeck (DLVO) theory. This chapter describes a model based on the control of coagulation by surface steric barriers of polysilicate a…
Silicon dioxide is the main component of the crust of the earth. Combined with the oxides of magnesium, aluminum, calcium, and iron, it forms the silicate minerals in our rocks and soil. Over millions of years silicon dioxide, or silica, has been separated from the original silicate rocks by the action of water to app…
Abstract : This report describes the results of 4 months of exposure to the Naval Environment of an aircraft carrier flight deck on a variety of aircraft materials and coatings. Test specimens included aluminum-lithium alloys, metal matrix composites, laminates and primerless paint.
New, “three-dimensionally structured” porphyrins were prepared in very few steps from β,β′-disubstituted pyrroles. In the corresponding biconcave metalloporphyrins (shown on the right) the peripheral groups on both sides of the porphyrin plane limit axial access to the metal center. For this reason selective interacti…
Studies at the Swiss Federal Technical Institute (ETH), Zurich, have produced results that, if confirmed by further research, could pose problems for the developers of catalytic converters that reduce emissions from diesel and lean-burn gasoline engines. The Swiss researchers have found that catalytic reduction of nit…
Abstract The electrochromic behavior of polyaniline–poly(vinyl alcohol) composite films (CPAn–PVA) combined with electrochemically synthesized Prussian blue films (PB) was investigated in LiClO 4 CH 3 CN nonaqueous aprotic solution. The combination was achieved by chemical deposition of CPAn–PVA on PB. When the combi…
An Fe-N film was deposited on a GaAs(100) substrate by ion-beam-assisted deposition at an N/Fe atomic arrival ratio of 0.12. The results from X-ray diffraction showed that the film consisted of the Fe 16 N 2 phase. The results of an annealing experiment indicated that the Fe 16 N 2 phase formed is stable after anneali…
Abstract The effect of fiber reinforcement on the crystallization kinetics of poly(ethylene terephthalate), or PET, was investigated using differential scanning calorimetry. The objective of the study was to determine how the effects of fiber reinforcement on PET crystallization are modified by the presence of polymer…
Visible electroluminescence with a peak wavelength of 6300 Å is observed from forward-biased porous Si p-n diodes with conducting polymer contacts. These devices have brighter electroluminescence than similar devices with thin, gold-film contacts. Electroluminescence is also observed from conducting polymer/n-porous S…
Abstract Investigations have been carried out on the effect of several zinc dithiocarbamates in the presence of thiazole‐based accelerators in the vulcanization of natural rubber (NR), keeping in mind the possibility of introducing safe dithiocarbamates derived from safe amines. Mutual activity is observed in all the…
Abstract Nonisothermal differential scanning calorimetry data for neat polypropylene and polypropylene with variously treated cellulose fillers has been used to solve for the Avrami exponent, n . Results show neat polypropylene to have an Avrami exponent value very close to the theoretically excepted value of 4.0. The…
The in-plane thermal expansion of thick freestanding polycrystalline diamond films produced by hot filament chemical vapor deposition was measured by dilatometry. Measurements were obtained from two different diamond wafers over a temperature range of −200 to +800 °C. Within experimental error of the measurements, val…
Abstract Nucleating agents increase the impact strength, tensile strength, and tensile elasticity modulus of semicrystalline polymers. Nucleating agents also decrease product cycle times, resulting in a cost savings per product unit. We have synthesized and tested 15 compounds as nucleactors for polypropylene. Of thes…