Characterisation of the neutral oil from a low-temperature coal tar

Tar resulting from fluidised-bed, low-temperature carbonisation of coal was treated to yield a neutral oil from which a series of six other samples was extracted. These were examined by proton magnetic resonance (p.m.r.) spectroscopy, low-ionising-voltage (11 eV) mass spectroscopy (m.s.), gel chromatography followed by fluorescent indicator analysis, and cryoscopy. Aliphatic fractions separated chromatographically were also examined by infra-red spectroscopy. Distributions of hydrogen between chemical types were found for the several fractions from 60 MHz p.m.r. spectra and presented in terms of average structural parameters. M.s. analysis indicated negligible cracking of paraffin components, and the average molecular weight of 197 agreed well with cryoscopic determinations. For the carbon ratio, f_a, between aromatic and total, agreement between m.s. and p.m.r. depends on the p.m.r. structural analysis scheme adopted. P.m.r. and m.s. structural analyses of the aromatics emphasise the predominance of di- and tri-nuclears, with about 40% of available sites substituted, and the importance of acenes in lowtemperature carbonisation material. Gas and gel chromatography showed urea-adductable paraffins to be largely straight-chain C₁₀-C₂₆, much as for tars from carbonisation at higher temperature.     

Solving multicolumn equilibrium stage operations by total linearization

An efficient, reliable and easily programmed method for solving systems of equilibrium stage separation devices is described. The method is an extension of an algorithm developed by Ishii and Otto⁽⁹⁾ for single columns. It solves all equations simultaneously, takes advantage of the basic tridiagonal matrix form form of the linearized steady state equations and can handle configurations which include distillation columns, absorbers and reboiled absorbers. The solution for a thermally coupled distillation system is presented.     

Hertzian Stress Cracks in Beryllia and Glass

The effect of Hertzian stresses resulting from loads acting at the points of contact of beryllia spheres was determined. As-drawn glass and glass ground with various grades of silicon carbide were indented with beryllia spheres, 1 in. in diameter. Also, pairs of these beryllia spheres were pressed together. Circular cracks due to Hertzian stresses were produced; an optical technique was developed for detecting them in a beryllia surface. The outer crack radius was proportional to the cube root of the maximum applied load. Average values obtained for the respective inner crack radii were used to determine average values of the minimum load to fracture these materials. The average minimum load to fracture 1 in. diameter beryllia spheres in air at room temperature under dynamic loading was 235 1b. The crack radius in glass and beryllia was about 20% greater than the radius of the contact surface. This was not significantly affected (in glass) by flaw density. It is considered that the Hertz analysis does not give the correct location and value of the maximum tensile stress when finite displacements of material occur.     

Stability of Inorganic Fluorine-Bearing Compounds: II, Complex Fluorides

The thermal stabilities of some alkali and alkaline-earth fluosilicates and cuspidine when heated in atmospheres of dry and moist air were investigated. IN the decomposition of K₂SiF₆ the compound K₃SiF₇ was noted. The alkali and alkaline-earth fluosilicates lose SiF₄ whereas cuspidine does not. In moist air atmospheres, α-cristobalite is found among the residual products from the fluosilicates of sodium and potassium. K₂TiF₆ hydrolyzes, first at low temperatures to an intermediate series of compounds and then at higher temperatures to fluorine-free potassium titanates. Both K₂ZrF₆ and Na₅Zr₂FI₃ hydrolyze to ZrO₂ and the alkali fluoride by way of an intermediate heptafluoride (M₃ZrF₇).     

Gaseous ammonia as a refining agent for cottonseed oils

In this investigation the application of gaseous ammonia to cottonseed oil refining was explored. The ammonia reacted quantitatively with the free fatty acids in the oil; its solubility in coftonseed oil was determined as a function of pressure. In “degumming” it was more efficient in removing phosphatides than other agents. A reduction in refining loss resulted for oils refined with gaseous ammonia as outlined and compared with the standard AOCS cup loss analysis. However, the oil colors were substantially higher even though the ammonia treated oils were re-refined with caustic solution. Results using cottonseed oil-hexane “miscellas” containing less than 70% oil showed low refining losses, but the colors were estremely high. Above 70% oil content the losses were higher, but the colors were lower. The colors never equalled “standard cup” results. This study was sponsored by the Texas Engineering Experiment Station and the Cotton Research Committee of Texas.     

Experimental methodologies to evaluate allelopathic plant interactions

It is difficult to clearly and unambiguously demonstrate an allelopathic mechanism of plant interference. Several types of experimental methodologies such as the additive design, substitutive designs, and several types of plant yield-plant population functions are discussed in terms of their relative merits in terms of providing quantitative and qualitative information in the development of an empirical basis to describe a plant interaction. Additionally, several types of mathematical and graphical representations are presented using data from the velvetleaf (Abutilon theophrasti) and soybean (Glycine max) interaction. The design provides agronomically relevant information about crop yield losses but confounds the separate effects of population density and species proportion in mixtures. The replacement series design separates these two variables by maintaining a constant population of plants while varying the relative proportion of each species in mixtures. The replacement series diagram, relative yield, relative replacement rate, ratio diagram, a scaling test, and the regression of individual yield on the associate yield are discussed in terms of their utility in providing insights into a plant interaction. Individual plant yield-plant population functions such as the “Y-D” and “C-D” effects, the “3/2 power law of self-thinning,” and the “Sakai” test provide a basis to compare plant yield per plant versus plant population responses. Several types of interactions are characterized with this methodology. None of these experimental designs will clearly demonstrate an allelopathic plant interaction alone, but they do provide high-inference experimental methodologies to develop an empirical foundation to describe accurately a plant interaction upon which more specific hypotheses can be developed.     

A generalized analysis of hysteresis in mercury porosimetry

Modifications in hardware, including the addition of a computer, and in operating procedures, were made to a commercial mercury porosimeter to facilitate thermal and mechanical equilibration. These modifications reduce temperature changes in the hydraulic fluid which cause an ‘apparent hysteresis’ even in the mercury-only blank. These modifications also allow the allocation of additional time for slow processes such as mercury extrusion from the porous samples analyzed in this work.Hysteresis observed between intrusion and extrusion mercury porosimetry data has been interpreted by a generalized analysis. Without specifying a particular pore shape, detailed features of sample compaction, mercury retention, and contact-angle changes can be identified by this method. The hysteresis in the mercury porosimetry data of the samples analyzed in this work are completely consistent with contact-angle hyteresis.     

Thermal analysis of styrene–alkyl methacrylate polymers. I. Glass transition temperatures

The glass transition temperatures (T_g's) of several polystyrenes and styrene–alkyl methacrylate copolymers and terpolymers were measured using thermomechanical analysis (TMA) and differential scanning calorimetry (DSC). The polymers studied had number-average molecular weights from 3000 to 250,000 g/mole. The results indicate that the composition dependence of the T_g's for the copolymers and terpolymers can be satisfactorily described by a general Fox equation. In general, the measured T_g's of the copolymer and terpolymer samples depend more on the steric effects of the constituent pendent groups than on their molecular weights. The chain flexibility rather than the size of the pendent group is the determining factor in the glass transition properties of the styrene polymers.     

Note: The Use of Triallyl Cyanurate in Bonding PVC Plastisols to Steel

The use of diallyl phthalate as the basis for a non-extractable plasticizer for poly(vinylchloride) (PVC) is well-known. Used in conjunction with a primary plasticizer and a polymerization initiator, a plastisol coating for steel can be formulated which is oil or grease tolerant and can also be used for bonding some structural steel parts if the area is relatively large compared with the load to be applied. Defrayne and Twiss¹ describe the bonding of automobile hood assemblies by vinyl plastisol adhesives and Schneberger² emphasizes their use in the automobile industry though neither article gives the formulations employed. Commercial formulations giving pull-off strengths of the order of 1 to 4 MN. m^-2 always incorporate a proportion of a phenolformaldehyde resin or even an epoxy, but sound-deadening and other coatings of steel do not necessarily need this reinforcement. Phillips and Longworth³ particularly studied the use of diallylphthalate (DAP) as a polymerizable plasticizer and the consequent improvement in adhesion to mild steel. Sherlock⁴ used a simple formulation without additives when investigating the effect of surface cleaning and conversion coatings (oxides and phosphates). It was suggested that, as outlined below, improved adhesion would be expected if a small proportion of triallyl cyanurate (TAC) were added to the polymerizable plasticizer. This paper shows this expectation to be achieved although the proportion of the more expensive TAC needed for substantial increase in bond strength is greater than was hoped.     

Agglomeration kinetics of coking coal particles during the softening phase

Agglomeration kinetics under thermal conditions describe the structure and formation of larger bodies, termed agglomerates from coal particles, as a preliminary phase of semi-coke formation. Knowledge on particle adhesion characteristics are of particular importance for determining the strength as well as the structure of the agglomerates. Several adhesive forces acting during the adhesion mechanism may be roughly subdivided into bonding with and bonding without material bridges. The purpose of the present work was to investigate the adhesion mechanism; the formation and growth in time of the bonding neck between two particles, as well as the change of functional correlation with other parameters, i.e. temperature and coal quality. Experimental investigation of the kinetics of agglomeration was carried out using apparatus in which a coal layer was heated by radiation in an atmosphere of flowing nitrogen. Camera recordings allowed quantitative assessment of the growth of the bonding neck with time, and additionally the dependence of the parameters on temperature and coal quality could be determined. The evaluation of the tests yielded clear indications supporting the assumption that increased adhesion of two viscous spheres under the effect of surface tension can be used as a physico-chemical model for the agglomeration of two coal particles under thermal conditions.