Effect of lubricant inertia in bearings with a non-Newtonian lubricant

Summary The inertia effects in externally pressurized and squeeze film bearings with lubricants obeying a power law are considered. It is found that the inertia forces decrease the load capacity of the externally pressurized bearing with a given flow rate and the inertia effect increases with the flow behaviour index. At a given feeding pressure, on the other hand, the inertia increases or decreases the load capacity when the flow behaviour index is smaller than or greater than 3, respectively. For squeeze films between circular plates and rectangular plates, the rate of squeeze is slowed down by the inertia and the inertia effect is larger in dilatant lubricants than in pseudoplastic lubricants.Nomenclature 2a diameter of the bearing, width of rectangular plates - 2b diameter of the recess - 2h film thickness - 2h ₀ initial thickness of squeeze films - l length of the rectangular plates - m consistency index - n flow behaviour index - p pressure - p _e external pressure - p _i feeding pressure - q flow rate - r radial distance - t time - u velocity of the lubricant - v squeeze velocity - w load capacity - W dimensionless load capacity - axial distance - viscosity of the lubricant - density of the lubricant     

Determination of Hansen Solubility Parameters for the Solid Surface of Cellulose Acetate Butyrate by Inverse Gas Chromatography

The specific retention volumes, , for adsorption of 21 solute probes on the solid surface of cellulose acetate butyrate (CAB) were determined in the temperature range 343.15 to 403.15 K by inverse gas chromatography (IGC). The weight fraction activity coefficients, , and Flory–Huggins interaction parameters, , were evaluated using . Both and values decreased with increase of temperature in all the solutes. Further, the values increased with increase of chain length in n-alkanes, but in the case of alcohols the trend was reversed. values were less than 0.5 in polar solutes and greater than 0.5 in 1-alkanes and alcohols. The Hansen solubility parameters (HSP) were calculated by relating with the cohesive energy of adsorption of the solutes on the surface of CAB. The adsorption model proposed by Snyder and Karger was used to determine the HSP for the CAB. The dispersive, , polar, , and hydrogen bonding components of HSP decreased with increase of temperature and the relative error associated with these parameters increased with increase of temperature. The characterization of the solid surface of CAB in terms of the three solubility parameter components was analyzed and is discussed.     

Electro—Optic and Dielectric Studies in Cholesteric Liquid Crystal Mixtures

In binary mixtures of cholesteryl chloride and cholesteryl alkanoates, the threshold field for the cholesteric to nematic transformation depends on the length of the alkanoate ester chain. The threshold field also depends on the pitch, the dielectric anisotropy and the twist elastic constant of the mixtures. This paper describes the experiments performed to establish the role of these three parameters in the observed variation of threshold field with alkanoate ester chain length in such binary mixtures.

The temperature dependence of threshold field, dielectric anisotropy and pitch has been studied. From these experiments the relative response of the various mixtures to applied electric fields has been established. In most of the mixtures, temperature ranges over which pretransitional effects do not predominate, have been identified. Twist elastic constants of the mixtures in these temperature ranges have been calculated. It has been shown that both the intrinsic response of the mixtures to applied electric fields, and the twist elastic constants do not show a regular variation with chain length of the alkanoate ester tail. Some observations suggest that mixtures containing non-smectogenic alkanoates show different temperature dependence of threshold field as compared to those containing smectogenic alkanoates.     

Novel ZnCl2-catalyzed one-pot multicomponent synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines

ZnCl₂-catalyzed one-pot multicomponent synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines under microwave heating and conventional heating is described.     

Inertia effects in hydromagnetic lubrication

Summary A theoretical investigation of inertia effects in a squeeze film bearing with an electrically conducting lubricant in the presence of a uniform transverse magnetic field is presented. The two cases of infinitely long rectangular plates and circular plates as bearing surfaces are considered. It is shown that the load supporting capacity of the bearing increases and the squeeze decreases if the lubricant inertia effects are taken into account. However, the inertia effect becomes smaller when the strength of the magnetic field increases.     

Mechanical and Thermo-Physical Properties of Fish Tail Palm Tree Natural Fiber–Reinforced Polyester Composites

The main objective of this article is to introduce a newly identified fish tail palm tree natural fiber as reinforcement in the development of partially biodegradable green composites. The tensile strength, tensile modulus, and impact strength of the composite are 1.54, 1.83, and 9.8 times greater than those of pure resin, respectively. The thermal conductivity of the composite decreased with increase in fiber content and the opposite trend was observed for temperature. The effect of temperature on specific heat capacity and thermal diffusivity of the composite was also considered and discussed.     

An efficient synthesis of silyl ethers of primary alcohols, secondary alcohols, phenols and oximes with a hydrosilane using InBr3 as a catalyst

An efficient method for the preparation of silyl ethers by InBr₃ catalyzed silylation of primary alcohols, secondary alcohols, phenols and oxime with a hydrosilane is described.