Relationship of peroxide value and thiobarbituric acid value to development of undesirable flavor characteristics in fats

The peroxide value and thiobarbituric acid value were compared with the flavor score for a series of different types of fats, with and without added monoglyceride and with and without different stabilizers. The data indicated that the flavor score cannot be estimated for any given fat from either the peroxide value or the thiobarbituric acid value. Either can be used to follow the development of off flavors in a given product or formulation but the relative level may vary from product to product. Presented at the AOCS Meeting in Minneapolis, 1963.     

The creep of kevlar-29 fibers

Single Kevlar-29 fibers have been subjected to creep loading over a temperature range of 23 to 400°C for which the applied load was 50 percent that of tensile strength at each temperature considered and also subjected to a range of loads at 23°C. It has been shown that strain expressed as a logarithmic function of time describes the experimental results obtained. Up to 70 percent of breaking load, a primary creep mechanism dominates and at higher loads a secondary creep process becomes increasingly important.     

Precipitation Studies in the System WC-Tic

The solubility of WC in TiC was found to vary from 50 mol% at 2050°C to 75 mol% at 2350°C; WC was precipitated from solid solutions containing 75 mol% WC-25 mol% TiC and 65 mol% WC-35 mol% TiC at 1900°C. The precipitated WC occurred as well-aligned ribbon-shaped particles. The crystallographic orientation of the precipitate and the matrix established by electron diffraction techniques is [100]_WC[110]_TiC and [010]_WC[001']_TiC. The interfacial planes were (001) for WC and (111) for TiC solid solution. Diffraction spot splitting occurred for all reflections of precipitated WC except the 001 type, indicating that compression of WC along the [110] direction took place, resulting in an apparent orthorhombic symmetry. This phenomenon was explained on the basis of the specific volumes and the difference in thermal expansion coefficient between WC and the solid solution. Tungsten carbide precipitated rapidly in the presence of Co, with all the WC precipitating in the form of platelets randomly oriented around the matrix grains. The hardness of the solid solutions 65 mol% WC-35 mol% TIC and 75 mol% WC-25 mol% Tic increased ∼10% and ∼23%, respectively, after they were annealed at 1900°C.     

Changes in the properties of Novoselits kaolin during heating

Conclusions Intensive dehydration and breakdown of kaolin briquette occurs at 400–600°C. Preliminary calcination of the kaolin at temperatures of up to 700°C reduces its cracking propensity with subsequent thermal shock which should favorably affect the reduction in dust emission and the formation of fine fractions of chamotte when it is being fired in rotary kilns.Surface-active agents (0.2–1%) reduce the cracking of raw kaolin specimens during thermal shock at 700°C, but to a less degree than preliminary dehydration.The sharpest change in the properties of kaolin briquette occurs at 1000–1250°C between the first and second exothermic effects.Additions of quartz sand appreciably increase the water absorption and porosity of kaolin chamotte, and reduce the apparent density, while additions of Gibbsite have a slight effect on the properties of the chamotte.Translated from Ogneupory, No. 5, pp. 40–47, May, 1971.     

Oxidation induction time correlations with radiation dose and antioxidant concentration in EPR and XLPE polymers

Oxidation induction time (OIT), as measured by differential scanning calorimetry, is useful in assessing the extent of degradation in polymeric materials. Values of OIT for typical EPR and XLPE polymer insulation materials used for electric cable insulation in nuclear power plants were measured as a function of both radiation dose and antioxidant concentration after accelerated aging. Irradiations were performed at the University of Virginia Cobalt Irradiation Facility. OIT was found to decrease exponentially with increasing radiation dose and with decreasing antioxidant concentration for both ethylene-propylene rubber (EPR) and cross-linked polyethylene (XLPE) insulations. It was determined experimentally that, when polymers are subjected to a constant radiation dose rate, antioxidant concentration decreases linearly with time, and it was shown that this variation is consistent with theoretical autoxidation kinetics. © 1993 John Wiley & Sons, Inc.     

Influence of variables in nickel-manganese-zinc alloy plating from a sulphate bath

An Ni-Mn-Zn alloy has been satisfactorily electrodeposited from a sulphate bath containing nickel sulphate (20–23 g dm⁻³), manganese sulphate (76–88 g dm⁻³), zinc sulphate (18–24 g dm⁻³), ammonium sulphate (30 g dm⁻³), thiourea (18g dm⁻³) and ascorbic acid (0.8 g dm⁻³) under various plating conditions, namely, current density 1.0–3.0 A dm⁻²; temperature 30–45° C; pH 2.7–4.2 and duration of electrolysis 15–30 min. Semibright, blackish-grey, thin films were generally deposited with the proportion of nickel and manganese in the deposits increasing with increasing current density, temperature and duration of electrolysis. However, the amount of zinc increased as the pH of the solution was raised. The cathode efficiency for alloy deposition increased linearly as the temperature or the pH of the solution was decreased, whereas at any particular pH and temperature it continuously rose with increasing current density or the time of deposition. The cathode polarization shifted to more negative values on increasing the current density and to less negative values at higher pH values and temperatures which consequently lowered the throwing power under the latter conditions.     

In situ densification of SHS composites from nanoreactants

The primary objective of this investigation was focused on in-situ densification of SHS composites synthesized from nanoreactants. Simultaneous combustion synthesis and densification technique was utilized and it was found to be an effective method to form dense intermetallic-ceramic composites. In this research study, two nanoreactant energetic systems, Al-TiO₂ and Ni-Al-Al₂O₃, were explored. In-situ combustion synthesis and densification experiments were conducted in a uniaxial press with densification pressures up to 200 MPa and preheating capability of 1500K. The experiments were conducted in both vacuum and Ar atmosphere. Samples of titanium aluminides-alumina composites with density in the range of 95–98% have been obtained at a preheating temperature of 860°C and pressure of 100 MPa. Reactants and SHS-produced materials were characterized by SEM, XRD, BET, and DSC/TGA. In addition, more fundamental studies of the reaction kinetics as a function of average particle size of aluminum nanopowders were conducted using DSC.      

Hydrodynamic drag forces on two porous spheres moving along their centerline

This paper numerically evaluates the hydrodynamic drag force exerted on two highly porous spheres moving steadily along their centerline (sphere #1 and sphere #2) through a quiescent Newtonian fluid over a Reynolds number ranging from 0.1 to 40. At creeping flow limit, the drag forces exerted on both spheres were identical. At higher Reynolds numbers the drag force on sphere #1 was higher than sphere #2, revealing the shading effects produced by sphere #1 on sphere #2. At dimensionless diameter (β, =d_f/2k^0.5, d_f and k are floc diameter and interior permeability, respectively) >20, the spheres can be regarded nonporous. At β<20, the drag forces dropped. At β<2, the drag forces approached “no-spheres” limit. An increased size ratio of two spheres (d_f1/d_f2) would increase the drag force on sphere #1 and reduce that on sphere #2. At increasing β for both spheres, the drag force on sphere #2 was increased because of the more difficult advective flow through its interior, and at the same time the drag was reduced owing to the stronger wake flow produced by the denser sphere #1. The competition between these two effects leads to complicated dependence of drag force on sphere #2 on β value. These effects were minimal when β became low. Two identical spheres could move steadily along their centerline. At higher Reynolds number, the two spheres would move closer because of the incorporation of inertia force. For spheres of different diameters, the sphere # 2 would move faster than sphere #1 regardless of their size ratio and β value. This occurrence yielded efficient coagulation when two porous spheres were moving in-line.     

Observations on the relatively high strength of a chalk-aggregate concrete

It has been observed that concrete containing chalk aggregate had a higher compressive strength than other wise similar concrete which contained basalt aggregate, although the chalk rock had a lower compressive strength than the basalt. Measurements of the rates of development of hardness of concrete containing these aggregates, measurements of the surface areas of these aggregates and X-ray examinations of the crystal phases in the set cement are reported and discussed. It was concluded that the relatively low strength of concrete containing basalt aggregate may be due to development of a phase, not chemically identified in the present work, which had a relatively weak bonding strength to the augite crystals in the basalt concrete.