bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of variables in artificial weathering on the degradation of selected plastics
Authors: Kamal Musa R.
Published: December 2004

Artificial weathering devices are used extensively by the plastics industry to aid in the prediction of the weatherability of plastic matrials. Correlations between the results of outdoor and artificial weathering, however, are poor for lack of control and understanding of the exposure variables in these devices. This work summarizs some of the results of an experimental program designed to analyze the effects of variables in artificial weathering on the preoperies of selected commercial plastics. In addition to the presentation of data establishing the importance of each of the variables in artificial weathering, a discussion of the significance of these data with regard to the selection of optimum exposure cycles is given. Furthermore, some new approaches are proposed with regard to obtaining inproved correlations between the results of outdoor and artificial exposure. Model calculations based on the proposed approaches yield a surprisingly high degree of correlation between the two types of exposure.
Time dependent crystallinity of polybutene‐1
Authors: Choi S. Y. , Rakus J. P. , O'Toole J. L.
Published: December 2004

Isotactic Polybutene‐1 can exist in 4 different crystalline phases of varying stability of which two are of greatest importance because they are involved in solidification from the melt initially, the melt cools into an unstable crystalline phase which gradually and spontaneously transforms into a stable, stronger, stiffer, more crystalline phase over a period of days. Rate of development of mechanical properties depends on crystallinity which depends on rate of phase change. However, optical properties develop in an unusual and irregualr way that is significantly affected by external factors, suxh as pressure, temperature, fillers nucleation and geometry.
Application of the rheology of monodisperse and polydisperse polystyrenes to the analysis of injection molding behavior
Authors: Hagan R. S. , Thomas D. P. , Schlich W. R.
Published: December 2004

Monodisperse and polydisperse polystyrenes of equal weight average molecular weight (Mw) are evaluated for melt flow behavior in an Instron capillary rheometer and for injection molding behavior in a 12 ounce in‐line reciprocationg screw injection molding machine. The influence of molecular weight distribution on the shape of the flow curves is deconstrated over a wide range of shear rate and temperature. The influence is also reflected in injection molding behavior as defined by pressure to fill or flash the mold at a given melt temperature. Studies of capillary rheometer data for correlation with injection moling beghavior indicate poor agreement when low shear rate viscosity data are used. Good agrement is foun using high shear rate viscosity data in the range 103 to 104 sec−1 Striking crossover points on melt rheology and injection colding area diagram curvs are found with the monodisperse and polydisperse polystyrenes of the same M These crossovers shift with melt temperature and make possible the determination of a “controlling shear rate” for the injection molding process. This is found to be 3500 sec−1 for short shot and 6200 sec−1 for flash with the ASTM test specimen mold used in this study.
The influence of microstructural characteristics on the failure properties of a polybutadiene system
Authors: Martin Donald L.
Published: December 2004

The stress‐strain characteristic of polymeric binders and solid propellants are dependent on the crosslink density, molecular weight between crosslinks, molecular weight distribution in the binder formulation, volume fraction of filler, and the interaction between the binder and filler particles. This investigation is directed toward elucidation of solid propellant microscopic response and failure mechanisms through characterization of the constitutive effects of crosslink density, molecular weight distribution and curing agent ratio in the binder formulation, and filler fraction. This was accomplished on the ERLA/PBAA propellant system through investigation of three binder formulations with the same curing agent ratio but different crosslink densities; five binder formulations with different curing agent ratios; and four formulations with up to 69.9% by volume of filler.

Uniaxial stress‐strain characteristics were determined on each formulation at displacement rates of 0.2 to 20.0 in/min at isothermal test conditions ranging from 75 to −90°F. The failure characteristics of a viscoelastic material represent a curve in the three‐dimensional space of stress, strain, and time. The ultimate property data on each formulation are presented as projections of this failure curve on the stress‐strain, stress‐time, and strain‐time planes, respectively. Relationships are developed for the dependence of the stress‐time, strain‐time, and stress‐strain failure envelopes on the volume fraction of bound rubber, crosslink density, molecular weight distribution and curing agent ration in the binder component, and the volume fraction of filler.
A simple, versatile and inexpensive rheometer for polymer melts
Authors: Best D. M. , Rosen S. L.
Published: December 2004

A simple, versatile biconical rehemoter has been developed. This device provides shear creep and creep recovery data for polymer melts over a temperature range of 200–500°F. and a range of applied shear stresses from 2 × 103 to 9 × 105 dynes/cm2.

Extensive reheological data have been obtained for two samples each of polyisobutylene and high‐density polyethylene. These illustrate the value of the device in obtaining data useful for predicting and understanding the processing properties of polymer melts.
Designing against fracture in brittle plastics
Authors: Williams J. G. , Radon J. C. , Turner C. E.
Published: December 2004

The fracture toughness of a variety of sharply notched tension, bending and rotating disc specimens of PMMA is examined using linear fracture mechanics. It is observed that rapid fracture with a brittle glassy appearance usually follows a period of slow crack growth, denoted by fan shaped markings of local ductility, though still brittle overall. In this near brittle regime the fracture toughness is sensitive to strain rate so that high values of effective surface energy are easily induced by rapid testing or notch bluntness. At impact rates the toughness increases again. For design purposes, in the absence of environmental effects, the onset of slow cracking and rapid (glassy) fracture, can be associated with fracture toughness K1c of about 800 Ibf/in3/2 (90 kg/cm3/2) and 1600 Ibf/in3/2 (180 kg/cm3/2) respectively. Detailed studies have not been made on other materials but a guide to the levels of notch toughness and notch brittle temperatures are given for several plastics.
Application of time‐temperature superposition principle to long term engineering properties of plastic materials
Authors: Seitz J. T. , Balazs C. F.
Published: December 2004

Time‐temperature equivalence was used to predict the long term engineering behavior of highly crystalline ethylene‐butene copolymers. The long term behavior (greater than 1000 hrs.) was accurately predicted from tests of short duration (30 hrs.). This time‐temperature principle was applied to stress‐relaxation and creep at stresses, strains and temperatures normally encountered in engineering practices. It was also used to solve a design problem involving the creep deformation of metal plastic laminates. Long term tests were performed to confirm the predicted results. This technique was not applicable to rubber modified polystyrene because of an unexpected transition at 88°F.
A study of the tensile strength of short fiber reinforced plastics
Authors: Lees J. K.
Published: December 2004

An experimental study of the tensile strength of unidirectional short fiber reinforced plastics is reported. The data indicate agreement with existing theories as modified to suit plastics. The theory is extrapolated to provide a means for computing the strength of a random composite.
Deformation and aging of quenched polypropylene
Authors: Gezovich D. M. , Geil P. H.
Published: December 2004

The physical properties, i. e., yield stress and stress‐strain curve of the quenched (“smectic”) form of polypropylene have been shown to be time dependent at room temperature. The yield stress increases linearly with the logarithm of film age. No changes in the x‐ray diffraction pattern, infra‐red spectrum, electron diffraction pattern or morphology have been observed corresponding to this change in physical properties. A molecular mechanism is proposed which will explain this again process. Spherulites of the quenched form have been found to deform affinely when drawn. In contrast to this, slow cooled films show complete destruction of internal spherulite (lamellar) order, indicating a complex mechanism of deformation.
Prediction of melt viscosity flow curves at various temperatures for some olefin polymers and copolymers
Authors: Mendelson R. A.
Published: December 2004

A knowledge of the variation of melt viscosity of thermoplastic polymers with both shear rate and temperature is of considerable importance to plastics engineers as well as to polymer rheologists. The actual measurement of melt viscosity at a large number of temperatures and shear rates is frequently a tedious and time‐consuming task. A technique has been developed, based upon the applicability of shear rate‐temperature superposition, for predicting the flow curves of a number of olefin polymers and copolymers at various temperatures from experimental data obtained at one temperature for the material in question. The experimental validity for superimposing log shear stress—log shear rate curves at different temperatures along the log shear rate axis has been established for both high and low density polyethylenes, polypropylene, polybutene‐1, and poly (ethylene vinyl acetate) copolymers. The temperature dependence of the resultant shift factors has been determined for each system, and the method of utilizing this information to predict viscosities as a function of temperature and shear rate is discussed.
Particle size measurement of the dispersed phase in rubber modified polystyrene
Authors: James D. E.
Published: December 2004

A widely accepted method for determining the particle size of the dispersed phase in impact polystyrene is by the microscopic examination of microtomed sections or dilute solutions of the polymer. Although this technique is relatively quick, it has obvious shortcomings to its statistical relaibility. In an effort to obtain more meaningful data, a Coulter Counter was employed to measure the average particle size and particle size distribution of the dispersed phase in a number of impact polystyrene samples. The materials examined contained rubber particles ranging from one to twenty microns in diameter. It was found that the weight average distribution of these particles was most nearly described by a log‐normal probability function. The relative accuracy and reproducibility of the measurements made with the Coulter Counter suggest that it is a valuable tool for obtaining quantitative particle size information on the rubber modified polystyrene system.
Morphology of plastic/rubber blends
Authors: Ho R. M. , Wu C. H. , Su A. C.
Published: December 2004

Blends of polypropylene (PP) and ethylene‐propylene rubber (EPR) and blends of polystyrene (PS) and styrene‐butadiene rubber (SBR) were prepared in a laboratory‐scale internal mixer at various blend compositions and rotor rates. Blend morphology was studied by means of electron microscopy. For each blend pair under the given processing conditions, the phase inversion process occurred progressively with respect to the variation in blend composition; it is within this composition range of phase inversion that dual‐phase continuity was observed. In addition, Characteristic torque values of blends were found to deviate negatively from a linear additivity rule; the composition range of maximum deviation from linear additivity corresponded approximately to the composition range where dual‐phase continuity was observed. Sperling's predictive scheme was found to yield acceptable (although not completely satisfactory) estimates for compositions of dual‐phase continuity in the present systems. It was also observed that partial cross‐linking of SBR during the mechanical blending process, as suggested by the appearance of a cure peak in the torque curve and supported by infrared spectroscopic evidence, resulted in morphological features drastically different from those of the uncured blends.
Characterization and processing of blends of polyethylene terephthalate with several liquid crystalline polymers
Authors: Sukhadia A. M. , Done D. , Baird D. G.
Published: December 2004

Blends of an engineering thermoplastic, poly(ethylene terephthalate) (PET), and two liquid crystalline polymers (LCPs) viz., copolyesters of PET and parahydrox‐ybenzoic acid (PHB) in 40/60 mole percent (LCP60) and in 20/80 mole percent (LCP80) were prepared. A blend of LCP60 and LCP80 in 50/50 weight percent (LCP60‐80) was blended with PET. Both flat films and rods were extruded and their properties examined. The morphology of the films investigated using Scanning Electron Microscopy (SEM) revealed that the LCP phase remained as dispersed droplets in the PET matrix. In spite of the lack of fibrillation in these films, the mechanical properties were enhanced to some extent with a maximum at 10 weight percent of the LCP phase. However, in the case of the rods thin fibrils of the LCP phase of the order of 1 μm in diameter were observed provided the composition of the LCP was 20 weight percent or greater. This success In achieving fibrillation is through to be due to the extensional flow fields present at the entrance of the capillary die and the fact that a short L/D ratio die was used. Differential Scanning Calorimetry (DSC) thermograms of the extruded films indicated that the LCP phase may act as a nucleating agent for the crystallization of PET. Rheology of the blends revealed that the complex viscosity of the blends is not much different from that of pure PET. This is attributed to the partial miscibility of the two components. Based on the DSC results and residence times in the extruder, it is concluded that no significant transesterification reactions appear to have: taken place in the blends. The rheology is studied further with respect to the cooling behavior of the pure components and factors important to the fibrillation of the LCP phase and the formation of in‐situ reinforced composites are discussed.
Morphology and mechanical properties of thermoplastic composites containing a thermotropic liquid crystalline polymer
Authors: Crevecoeur G. , Groeninckx G.
Published: December 2004

Blends of two thermotropic liquid crystalline polymers (TLCPs), with brittle and ductile matrix materials were both injection molded and spun into fibers, in order to investigate the mechanism of in‐situ mechanical reinforcement. In the injection molded samples, the TLCP was only moderately elongated into fibrils, and the mechanical properties were below predictions of the rule of mixtures. Fibers spun out of the blends contained numerous fine fibrils with nearly infinite aspect ratio, and as expected, the modulus increased linearly with the TLCP volume fraction, obeying the Tsai‐Halpin equation for transversely isotropic composites. Wide angle X‐ray diffraction measurements, as well as determination of the fiber‐moduli, revealed that during spinning not only a macroscopic elongation of the fibrils was achieved, but also a considerable molecular orientation within the TLCP domains.
Morphology‐processing relationships in polyethylene‐polyamide blends
Authors: Serpe G. , Jarrin J. , Dawans F.
Published: December 2004

Blends of polyethylene (PE) and polyamide (PA) were prepared by a melt mixing process. The dependence of the number average size An of the dispersed phase on hydrodynamic conditions not only of shear rate but also temperature, inter‐facial tension, viscosity of the blends (WU's treatment), and dispersed phase concentration were studied. The analysis of PE‐PA blend morphology shows An to be the result of a balance between coalescence and disruption of the particles in the melt, and to display a strong increase in particle size when the minor component concentration is enhanced. These observations can be explained by a change in the rheology of the system. These assumptions are confirmed by the insertion in the blend of an ethylenemaleic anhydride (EMA) copolymer that yields EMA‐g‐PA graft copolymer during mechanical processing. Formation of this graft copolymer has been indicated by a strong particle size reduction and its concentration was measured by infrared experiments. The EMA‐g‐PA copolymer seems to decrease the blend interfacial tension and to deter the coalescence process.
On the effect of nonhomogeneous flow fields on the orientation distribution and rheology of fiber suspensions
Authors: Shanker Ravi , Gillespie J. W. , Güçeri S. I.
Published: December 2004

The influence of nonhomogeneous flow fields on the orientation distribution and rheology of fiber suspensions is investigated. The Stokes‐Burger model is used to approximate the forces and moments on the fiber for the subsequent calculation of fiber angular velocities for nonhomogeneous cases where the velocity gradients vary over the fiber length. For simple shear flows, an analytical solution based on the Stokes‐Burgers model is derived. Fiber angular velocities are compared to previously published results. An iterative numerical technique is developed to calculate the otherwise indeterminate fiber angular velocities for other nonhomogeneous flows, such as non‐isothermal Hele‐Shaw flows. The value of shear is derived for which the angular motion of the fiber in a quadratic velocity field is identical to that in a linear shear flow. Subsequently, numerical solutions for orientation distribution functions are presented for cases where analytical solutions for distribution functions are not obtainable. The rheological properties are then studied, using the orientation tensor description, for nonhomogeneous flow fields where the fiber motion can be approximated by that in a shear flow, the equivalent shear rate obtained from the numerical scheme.
A study on bicomponent two‐layer slot cast coextrusion
Authors: Park Chang‐Won
Published: December 2004

Extensional flow of a bicomponent two‐layer slot cast coextrusion process has been studied. A Newtonian and an upper‐convected Maxwell fluid were considered to be the two layers, respectively, and the two‐layer flow was assumed to be steady and isothermal. This choice was made as a simple model for a system which consists of two distinctly different fluids in terms of their extensional behaviors. Present study considered only the draw‐down region where the film thickness changes slowly with the distance from the die exit. For this region, asymptotic solutions could be obtained for two limiting cases in which the elasticity effect of the Maxwell fluid layer is small and the applied tension at the take‐off is large, respectively. When the elasticity effect is small, the melt thickness and the velocity profiles are exponential as in the case of a Newtonian single‐layer flow. When the applied tension is large, on the other hand, the velocity profile is shown to be near linear. Furthermore, the viscoelasticity effect of the Maxwell fluid layer becomes so dominant that it dictates the mechanics of the coextrusion flow even when its flow rate and shear viscosity may be much smaller than those of the Newtonian layer.
The flow distribution of molten polymers in slit dies and coathanger dies through three‐dimensional finite element analysis
Authors: Wang Yeh
Published: December 2004

The isothermal flow of power‐law fluids in slit dies and coathanger dies is studied. A general three‐dimensional finite element code is developed for the purpose of flow analysis. The pressure distribution, the velocity distribution, and the transverse flow rate distribution are obtained. The effect of the die geometry on the flow distribution is critically discussed. It is found that a die channel with cross section of dog bone profile produces a flatter transverse flow rate distribution.
A polarized light scattering approach for dispersed phase morphology characterization in simulated polymer blends
Authors: Bélanger C. , Cielo P. , Patterson W. I. , Favis B. D. , Utracki L. A.
Published: December 2004

A light scattering technique using a normal‐incidence polarized light beam for the characterization of skin/core simulated polymer blend samples is described. The patterns of reflected, polarized scattered light from an inhomogeneous blend were captured using a video camera. The blend was illuminated from a focused laser source. The simulated samples were constructed by incorporating glass fibers (skin) and glass microspheres (core) in a polymer matrix. Asymmetrical patterns were obtained. They reflect the anisotropic nature of the near‐surface morphology. Moreover, the change of the anisotropy ratio of the iso‐intensity curves plotted, as a function of distance from the position of the incident laser beam on the sample, gives information about the skin and the core content as well as the skin thickness.
Quantitative model relating electrical resistance, strain, and time for carbon black loaded silicone rubber
Authors: Kost J. , Foux A. , Narkis M.
Published: December 2004

A quantitative model has been developed relating electrical resistance with strain and time for carbon black filled silicone rubber compounds. The model is based on concepts and methods used in the field of viscoelasticity. Relaxation experiments are performed in order to evaluate material parameters. With these, resistance‐strain‐history relations, under other loading conditions may be predicted.
On the Sizing Accuracy of Laser Optical Particle Counters
Authors: Szymanski W. W. , Liu Benjamin Y. H.
Published: December 2004

The performance of a narrow‐angle and a wide‐angle, forward scattering laser aerosol spectrometer has been studied as a function of particle size and refractive index. The results have been compared with theoretical calculations based on light scattering theory. The results indicate that for the narrow‐angle instrument, the scattered‐light intensity is not a monotonic function of particle size for transparent particles (a monotonic relationship is required for unambiguous particle size measurement) above 0.7 μm. The instrument is therefore limited in its useful range to size distribution measurement between 0.2 μm – its lower particle size limit – and 0.7 μm for transparent particles. In the case of the wide‐angle instrument, the instrument output is a monotonic function of particle size for transparent particles, but the output is severely attenuated for light absorbing particles above 0.3 μm. The instrument, therefore, cannot be used for accurate size measurements above 0.3 μm for light absorbing particles.
Pore Structure Analysis of Porous Particles by Equivalent Model
Authors: Yan Ji‐Min , Zhang Qi‐Yuan
Published: December 2004

Starting from Wheeler's composite theory, which takes both the multilayer adsorption and the capillary condensation into consideration, and assuming the equivalent cylindrical model, we have deduced a strict and relatively simpler formula for the calculation of pore size distribution
equation image
by solving the integral equation directly. The formula is more convenient for application because of its recursion form. Following the same line of reasoning and using the mean value theorem of definite integrals under different conditions, we have unified the equations of Barrett‐Joyner‐Halenda, Dubinin, Cranston‐Inkley, Dollimore‐Heal and Roberts. A table of parameters which is required in the calculation is given. Besides the adsorption of nitrogen, the adsorption with water vapor as the adsorbate is investigated and the corresponding empirical equation of adsorption thickness is given.
Determination of Nitroester and Stabilizer Migration in combustible cartridge case wall
Authors: Ho C.‐H. , Tomkins B. A. , Ramsey R. S. , Griest W. H. , Counts Richard W.
Published: December 2004

Propellant nitroesters (diethyleneglycol dinitrate and nitroglycerin) and stabilizer (Akardite II, N‐methyl‐N,N′‐diphenylurea) were determined in combustible cartridge case (CCC) wall specimens from 120 mm M829 rounds which had been exposed to elevated temperatures in environmental chambers or which were returned from deployment in Southwest Asia. The results suggest that the migration of these components from the propellant is uniform about the circumference of the adhesive joint between the CCC body and adapter but not longitudinally above and below the joint. The accumulation appears to be linear with time of exposure, with both nitroesters migrating at approximately the same rate with similar energies of activation. The conventional sampling and analysis method is compared with a new micro‐sampling and analytical method which reduces solvent waste and extraction time, and considerably reduces damage to the rounds from removal of the analytical specimen.
On the deflagration of aluminium/KClO4 mixtures
Authors: Hahma Arno
Published: December 2004

Explosive properties of KClO4/Al‐mixtures (60/40) were studied using 15 different types of Al powders. The explosions were photographed and the propagation speed was measured. The detonation and detonation isentrope properties of the mixtures were calculated and the results compared to the measured data. A condensed phase detonation was not detected but shock waves were most likely present in the gas phase. The results indicate that aluminium powder is not able to sustain detonation at all. Additionally, powder with a surface area less than 5 m2/g will not even deflagrate reliably as a mixture with potassium perchlorate.
Primer Compositions in the Course of Time: From black powder and SINOXID to SINTOX compositions and SINCO booster
Authors: Brede Uwe , Hagel Rainer , Redecker Klaus H. , Weuter Waldemar
Published: December 2004

Starting with methods used to ignite a propelling charge by means of a piece of glowing charcoal, iron or a burning match in the first firearms of the 14th century, this article contains a detailed description of the direction‐setting milestones and their effects on the development of handguns. The decisive turn‐around in ordnance engineering came with the discovery of impact‐sensitive mixtures and the manufacture or employment of primary explosives, such as mercury fulminate and, in particular, lead trinitroresorcinol and tetrazene, which were used worldwide in the SINOXID primer composition of Dynamit Nobel. With the development of a SINTOX primer composition which set standards by replacing lead, barium and antimony compounds of the SINOXID primer with harmless components, Dynamit Nobel, very early on took account of the public's increasing environmental awareness and health concerns. The same claim is met by the SINCO booster as an environmentally compatible and stable category of substances. Especially also suitable for gas generation in safety systems of motor vehicles for occupant protection. Over many decades, Dynamit Nobel's special achievements have always been characterized by new and innovative pioneering products meeting the changing needs of technology and environment.

In many of his entrepreneurial functions both inside and outside the company, Dr. Homburg has shown great scientific and technical competence as a committed exponent of chemistry and technology at Dynamit Nobel. This contribution on primer compositions is dedicated to Dr. Homburg on the occasion of his 60th birthday.
Short‐Action Solid Rocket Motors with Double‐Base Propellants
Authors: Kentgens H. , Mackowiak H. P. , Schöffl R.
Published: December 2004

Due to various reasons double‐base solid propellants have been replaced increasingly by composite propellants in the past years. However, the ALARM rocket motor of the Bayern‐Chemie GmbH is one exception. Applications ideal for double‐base propellants are short‐action rocket motors with burning times ranging from some milliseconds up to approximately 200 ms. Various rocket motors of this type were developed at Dynamit Nobel GmbH for different kinds of application. Based on multiple‐tube grains improved designs and manufacturing methods have been developed to enable cost‐effective solutions even at low production rates. This includes also simplified test procedures to supervise the propellant fabrication.
Flying Plate Detonator
Authors: Held Manfred
Published: December 2004

Design and function of an all‐secondary explosive low‐voltage electric detonator will be described. Results of the threshold values of current, voltage, energy will be presented together with the re‐sponse times, the initiation capability gainst boosters of tetryl and the results of a few safety tests.
Detonation Products as a Function of Initiation Strength, ambient gas and binder systems of explosives charges
Authors: Volk Fred
Published: December 2004

The way of initiating an insensitive high explosive can influence the start of a detonation reaction remarkably. In order to study the extent of this influence, different boosters and different booster structures for the initiation of explosive mixtures containing TNT and nitroguanidine (NQ) have been used. The experiments have been conducted in a 1.5 m3 containment from which the detonation products could be taken and analyzed. In those cases where we only used a 10 g RDX booster together with a detonation cap no. 8, we had not a complete detonation reaction by initiating cylindrical charges of TNT/NQ and TNT/AN. This means that unreacted TNT was analyzed in the solid residue, mainly consisting of carbon soot. On the other hand, we had a complete detonation using an additional booster of about 18 g detonation sheet, placed on the front side of the cylindrical explosive, having the same diameter as the explosive charge.

Another part of the investigations deals with the determination of the influence of different argon pressures on the composition of the detonation gas and the solid residue. Between vacuum and one bar argon a strong change not only of the gas but also of the soot residue was measured. A stronger influence on the products was found using a confinement with glass tubes.

The investigation of Al‐containing charges exhibited a very different behavior compared with charges without Al. No more influence of vaccum or of different ambient gas pressure could be observed. By investigation of two composite explosive charges (PBX) containing binder systems of different energies and different oxygen balances, a great influence on the reaction of Al was found. The PBX charges with the better O2‐balance containing the energetic GAP‐binder reacted nearly completely with the Al, opposite to the charge containing the polyisobutylene (PIB) binder system.
Studies on 2,4,6‐Trinitrophenyl Substituted Naphthalenes. Part II. Synthesis of nitro‐ and polynitro‐1‐(2,4,6‐trinitrophenyl)naphthalenes
Authors: Bergman John S. , Duffin Henry C. , Golding Peter , Wells Clifford H. J.
Published: December 2004

Mononitro‐, dinitro‐, trinitro‐ and tetranitro‐derivatives of 1‐(2,4,6‐trinitrophenyl)naphthalene have been synthesised using a variety of nitration procedures. The mononitro‐ and dinitro‐derivatives have also been synthesised from 1‐bromonaphthalene and 1‐nitronaphthalene via a combination of bromination, nitration and Ullmann reactions.
Synthesis of a New Organic Azide: 1,9‐Diazido‐2,2,8,8‐tetranitro‐4,6‐dioxanonane
Authors: Hong Yan , Xiaopei Guan , Boren Chen
Published: December 2004

The title compound has been synthesized from its appropriate bis(trinitroethyl)formal. For this compound the molecular structure has been determined, and some of the properties are also reported.
Synthesis of 2‐Nitro‐1,3‐Diazidopropane Derivatives
Authors: Naixing Wang , Boren Chen , Yuxiang Ou
Published: December 2004

2‐Nitro‐1,3‐diazidopropane derivatives were synthesized through a condensation reaction, substitution reaction and azideation. The molecular structure of the products have been determined by MS, IR, 1H‐NMR.
Sideways Plate Push Test for Detonating Solid Explosives
Authors: Tarver Craig M. , Tao William C. , Lee Chet G.
Published: December 2004

A Sideways Plate Push Test has been developed to quantitatively measure the radial acceleration history of a thin metal plate driven by a detonating solid explosive using Fabry‐Perot laser interferometry. This test is designed to compliment the radial expansion cylinder test and axial plate push tests for detonating solid explosives by measuring very precisely the velocity of the metal plate as the explosive reaction products expand from the Von Neumann spike to a volume of approximately three times the initial volume. 1.27 cm thick slabs of LX‐14 (HMX‐based) and LX‐17 (TATB‐based) were detonated to radially accelerate 0.5 mm thick copper and tantalum plates. The measured radial velocity histories of the plates were compared to two‐dimensional hydrodynamic computer code calculations of the experiment. These comparisons showed that the Chapman‐Jouguet (CJ) description of detonation, which neglects the effect of the chemical reaction zone, generally slightly overestimates the radial velocity history of the plate and that the Ignition and Growth Zeldovich‐Von Neumann‐Döring (ZND) reactive flow model, which includes the momentum associated with the chemical reaction zone, yields good agreement with the Fabry‐Perot results. This Sideways Plate Push Test is very useful for determining explosive energy release for applications which depend on the high pressure, early time expansion of the detonation reaction products.
Herbicide sorption to concrete and asphalt
Authors: Ramwell Carmel T
Published: December 2004

In order to accurately predict the fate and behaviour of herbicides following application to hard surfaces, an understanding of the processes involved is required. Previous studies have demonstrated that herbicides with a low soil organic carbon partition coefficient (Koc) are preferentially removed from concrete and asphalt surfaces. It is possible, therefore, that sorption may play a role in retaining herbicides to hard surfaces. This study provides an indication of the extent to which herbicides may sorb to concrete and asphalt, and examines the results in the light of other research to identify the significance of sorption in describing herbicide losses after application. There was measurable sorption of herbicides to concrete and asphalt although this was limited compared with that to soils, especially for concrete. An exponential relationship between experimentally derived values of Kp and literature values of Koc for asphalt was established (r2 = 0.931); there was a weaker relationship for concrete (r2 = 0.606). The experimentally derived Kp values could be used to enhance the prediction of herbicide loss to receiving waters following application. It is probable that the fate of herbicides applied to concrete and asphalt surfaces depends more heavily on physical processes than is the case in soils. Copyright © 2004 Society of Chemical Industry
Expression of a wheat cytochrome P450 monooxygenase in yeast and its inhibition by glyphosate
Authors: Xiang Wen‐Sheng , Wang Xiang‐Jing , Ren Tian‐Rui , Ju Xiu‐Lian
Published: December 2004

Glyphosate is a non‐selective herbicide which acts by inhibiting 5‐enolpyruvylshikimate‐3‐phosphate synthase. Wheat cytochrome P450 monooxygenase specifically catalyzes the metabolism of some sulfonylurea herbicides such as chlorsulfuron and triasulfuron. Here we report that glyphosate is an inhibitor of a wheat cytochrome (CYP71C6v1), the cDNA of which was amplified by RT‐PCR and heterologously expressed in yeast. The microsomal fractions derived from this strain had a Soret peak at 502 nm in the reduced carbon monoxide difference spectrum, which is a typical spectral characteristic. The addition of glyphosate to the microsomal protein resulted in a Type II spectrum indicative of binding via the nitrogen group to haem of cytochrome P450 as a sixth ligand. A spectral dissociation constant, Ks of 70 µmol litre−1 was observed and an IC50 of 11 µmol litre−1 was found for glyphosate inhibition of CYP71C6v1 P450 activity. Copyright © 2005 Society of Chemical Industry
New 2‐phenyl‐4,5,6,7‐tetrahydro‐2H‐indazole derivatives as paddy field herbicides
Authors: Hwang In Taek , Kim Hyoung Rae , Jeon Dong Ju , Hong Kyung Sik , Song Jong Hwan , Chung Chang Kook , Cho Kwang Yun
Published: December 2004

A series of 3‐chloro‐2‐(4‐chloro‐2‐fluorophenyl)‐4,5,6,7‐tetrahydro‐2H‐indazole derivatives containing various substituted isoxazolinylmethoxy groups at the 5‐position of the benzene ring were synthesized and their herbicidal activities assessed under greenhouse and flooded paddy conditions. Among them, compounds having a phenyl or cyano substituent at the 3‐position of the 5‐methyl‐isoxazolin‐5‐yl structure demonstrated good rice selectivity and potent herbicidal activity against annual weeds at 16–63 g AI ha−1 under greenhouse conditions. Field trials indicated that these two compounds controlled a wide range of annual weeds rapidly with a good tolerance on transplanted rice seedlings by pre‐emergence application. They showed a low mammalian and environmental toxicity in various toxicological tests. Copyright © 2005 Society of Chemical Industry
Towards a practical rechargeable 5 V Li ion battery
Authors: Eglitis R. I. , Borstel G.
Published: December 2004

Current lithium‐ion batteries are the state‐of‐the‐art power sources for consumer electronics operating mainly in the 4 V regime. One frequently discussed direction to improve the performance of such batteries is the development of a family of 5 V cathode materials. We report here a Full Potential Linearized Augmented Plane Wave (FP‐LAPW) calculation for Li2Co1Mn3O8 in the Fd$\bar 3 $m spinel structure. Our calculated battery voltage for this material is around 5 V. This result is stable against interchange of positions of Mn and Co atoms as well as the choice of the position of the Li vacancy. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of semi‐empirical parameters on the triplet energy levels and triplet–triplet transition in benzene
Authors: Sannigrahi A. B.
Published: December 2004

Triplet energy levels and triplet–triplet transition in benzene have been calculated semi‐empirically by considering CI up to and including doubly excited configurations and using various values of the core resonance and electron repulsion integrals. The usual method of calibrating β (core resonance integral) from one of the observed transitions in the semi‐empirical methods is critically examined with respect to the triplet levels of this molecule. Semi‐empirical parameters are found to have a pronounced effect on the energy of the triplets and the triplet–triplet transitions; but the intensities of such transitions are quite insensitive to the choice of such parameters.

Numerical results show several 3B1u → 3E2g transitions of various intensities. Out of these, the transitions which correspond energetically to the observed triplet–triplet bands are found to have low intensity. Some strong triplet–triplet bands are predicted in the far ultra violet region.
Theory of intermolecular forces. I. On the inadequacy of the usual Rayleigh‐Schrödinger perturbation method for the treatment of intermolecular forces
Authors: Claverie Pierre
Published: December 2004

The problem of intermolecular interaction is examined by using spatial wave functions and the theory of permutation groups. In the special case of interacting 2‐electron systems it is proven that the Rayleigh–Schrödinger perturbation method, when starting from the ground state of the unperturbed system, could only give the physically inadmissible mathematical ground state of the complex (totally symmetric spatial eigenfunction). Then this property is considered in the case of arbitrary interacting systems and a general proof is proposed. From these results a general explanation of the inadequacy of the Rayleigh–Schrödinger expansion for the treatment of short range intermolecular interaction is proposed.
The optimum projection technique in many‐electron treatments
Authors: Cantu A. A. , Hart‐Davis A.
Published: December 2004

The optimum projection technique is the determination of the best function in the space spanned by a set off f(N, S) linearly independent antisymmetric space‐spin eigenfunctions of S2 obtainable from a spatial function made of a product of N‐independent orbitals. This is formulated in the spin‐free framework. We consider several sets of predetermined orbitals for the lithium 2S state. Both the energy and spin‐density are determined for each optimum projected function. The behavior of certain results is explained in terms of the “closeness” of the ls and ls′ split‐shell core orbitals.
Many‐electron problems III scaling of the density distributions and the potential fields
Authors: Gáspár R.
Published: December 2004

The Hellmann–Feynman theorem has been used to prove some energy relations. In this paper it is shown that in a scaled co‐ordinate system both the charge density and the potential field of neutral atoms may be scaled so that the corresponding scaled quantities are independent of the atomic number. In the proof the momentum theorem of real functions is used.
Optimized linear combinations of simple exponentials for atomic systems
Authors: Solomon C. E.
Published: December 2004

Hartree‐Fock wave functions for the He and Be isoelectronic sequences of ions are calculated using orbitals which are linear combinations of simple exponential functions. By a full optimization of the exponents and coefficients close approximations to the HartreeFock energies were obtained. To the same order of accuracy the resulting Hartree–Fock orbitals require fewer basis functions than used previously. A number of difficulties which arise in the numerical procedures as the size of the basis set is increased are analysed in detail. Similar results are obtained for the Li sequence using the Unrestricted HartreeFock method with and without projection.
The generalized separated electron pair model. II. An application to NH, NH3, NH, NH2− and N3−
Authors: Robb M. A. , Csizmadia I. G.
Published: December 2004

The Separated Electron Pair (SEP) model (Strongly Orthogonal Geminals) and methods for its systematic extension has been applied to the series: NH, NH3, NH, NH2− and N3−. On going from NH to N3−, the SEP model, in its most general form, recovers 85–75% of the intrapair correlation energy and 60–55% of the interpair correlation energy obtainable with the given basis set. The best wave functions for each species recovered about 45–50% of the total empirical correlation energy which is expected to be very close to the basis set limit. It was apparent that the SEP model yields a set of one‐electron functions that are very useful for further improvement of the wave function. This fact apparently remains true even when the SEP model itself gives very poor energies.
Self‐consistent calculation of excited 3P state wave functions of atoms
Authors: Mukherjee P. K. , Bhattacharya A. K. , Mukherji A.
Published: December 2004

A variation perturbation method in the Hartree–Fock scheme has been described to calculate excited 3P state wave functions of atoms. The starting wave functions are obtained from a study of the singularities in the dynamic polarizability calculation [1]. The 23P, 33P and 43P states of He, Li+, Be2+, B3+ and C4+ are studied. The results obtained are in satisfactory agreement with experimental values and with other accurate theoretical estimates.
Symmetry properties of one‐ and two‐electron molecular integrals
Authors: Brailsford D. F. , Hall G. G.
Published: December 2004

The maximum numbers of distinct one‐ and two‐electron integrals that arise in calculating the electronic energy of a molecule are discussed. It is shown that these may be calculated easily using the character table of the symmetry group of the set of basis functions used to express the wave function. Complications arising from complex group representations and from a conflict of symmetry between the basis set and the nuclear configuration are considered and illustrated by examples.
Ab initio calculation of electronic states of the ions H4+ and H5+
Authors: Kaplan I. G. , Rodimova O. B.
Published: December 2004

Electronic state calculations for the ions H4+ (with symmetries D4 and C2v) and H (with symmetries D5 and D2d) are made using the valence‐bond method. All the configurations obtained from the given set of 1s‐functions of Slater type are taken into account. Space functions are used throughout the computation (“spin‐free quantum chemistry”). Preliminary quasidiagonalization of the secular equation is implemented by the construction of the multiplet eigenfunctions 2S+1Γ(α) from the initial variational functions. The results of the calculations are as follows: the ion H is unstable, the ion H is stable with equilibrium nuclear conformation of symmetry D2d and with the energy of dissociation into H and H2 near 4 eV.
On the nature of paramagnetism in macromolecules with conjugated cc bonds
Authors: Berlin A. A. , Vinogradov G. A. , Ovchinnikov A. A.
Published: December 2004

The paramagnetic properties of one‐dimensional macromolecules with conjugated CC bonds are discussed on the basis of low‐lying quasi‐homeopolar triplet excitations. A good agreement with the experimental results is shown.
Effect of methyl and hydroxyl substituents on the π‐electronic spectra and ionization potential of p‐benzoquinone
Authors: Mitra R. P. , Kapoor K. L.
Published: December 2004

SCF‐LCAO‐MO‐CI semi‐empirical π‐electron calculations have been made of the first two singlet transitions and ionization potentials of hydroxy‐, methyl‐ and hydroxy‐methyl substituted p‐benzoquinone, using a modified Pariser‐Parr‐Pople method. The various molecules could be divided into two classes on the basis of their first π‐electron transition, namely, those in which the 3‐position was occupied and others where this position was vacant.
On the translation between MO and HL descriptions of co‐ordination compounds
Authors: Farberov D. S. , Men A. N.
Published: December 2004

Wave functions for impurities or local complexes in crystals are usually described within one of the two popular schemes furnished by the MO and the HL methods. The purpose of the present note is to draw attention to a set of tables which allow a translation between these two descriptions.
Structure electronique des complexes acide‐base de Lewis. I. Structure electronique et conformation moléculaire des molécules F3P·BH3 et F2HP·BH3
Authors: Labarre J.‐F. , Leibovici C.
Published: December 2004

The electronic structure and preferred conformations of F3P·BH3 and F2HP·BH3 are investigated in the framework of the CNDO/2 approximation. In complete agreement with microwave data, the staggered conformations are predicted to be the most stable ones. The barriers to internal rotation are in good agreement with experimental values (F3P·BH3: calc. = 3.03 kcal/mole, exp. = 3.24 ± 0.15 kcal/mole; F2HP·BH3: calc. = 3.63 kcal/mole, exp. = 4.05 ± 0.45 kcal/mole) and a bicentric energy partitioning shows that the variations of the total energy are completely reflected by the only variation of the interaction energy between phosphorus and H atoms bonded to boron. The analysis of the electron densities reveals the importance of the 3s(P) → 2px(B) transfer in the formation of the co‐ordination. Finally, the computed dipole moment value and direction agree with corresponding experimental data.