bluuebunny/crossref_metadata_2025 huggingface dataset:
NMR spectroscopy, polymer motion, and “Tack” of model printing inks
Authors: Aspler Joseph S.
Published: December 2004

Polymer motion in solution and in model printing inks (as measured by NMR spectroscopy) was compared to the “tack” or tensile stress developed in the splitting of thin fluid films. For model inks based on polyisobutene, at constant pigment content, increasing the polymer content caused polymer motion to slow down, and caused the tack to increase. At constant polymer content, increasing the pigment level had much less effect on polymer motion. At 20% pigment content, tack values were little different from those of the corresponding polymer solutions. This suggests that the tensile stress developed in an ink film as it splits is related to the motion of its polymeric ingredients, but is much less dependent on the concentration of dispersed solid pigment.
The yield strength of particulate reinforced thermoplastic composites
Authors: Jancar J. , Dianselmo A. , Dibenedetto A. T.
Published: December 2004

The effects of the filler volume fraction and strength of adhesion on the mode of tensile failure of a particulate reinforced polypropylene (PP) are investigated using finite element simulation (FES). When there is perfect adhesion between constituents, an upper bound for tensile yield strength is found to be 1.33 times the matrix yield strength above a critical volume of particulate concentration. Utilizing Sjoerdsma's model for interacting stress concentration fields, one can determine the concentration dependence of the yield strength below the critical filler volume fraction. When there is no adhesion between constituents, a modified version of an equation by Nicolais and Narkis adequately describes a lower bound for the tensile yield strength. The particulate concentration and the matrix ductility are the prime factors in controlling the brittle failure of the composite. Upper and lower bounds for brittle failure strength are characterized using a strength‐of‐materials approach and stress concentration factors for both “perfect” and “zero” adhesion. The properties of calcium carbonate filled PP homopolymer were measured over a wide range of filler volume fractions. CaCO3 was either treated with stearic acid to prevent adhesion between constituents or used as received. Maleic anhydride grafted PP (MPP) was used to promote adhesion. For filler volume fractions below 0.2, yielding of the composite by combined microcavitation and shear deformation was the principal failure mechanism. At vf above 0.35, a brittle failure mechanism dominated. In the range between 0.2 and 0.35, both failure modes were observed in the populations tested. Good agreement was found between the experimental results and the proposed model.
Phase and crystallization behavior of solution‐blended poly(ether ether ketone) and poly(ether imide)
Authors: Chen Hsin‐Lung , Porter Roger S.
Published: December 2004

Results on solution‐blended poly(ether ether ketone) (PEEK) and poly(ether imide) (PEI) blends are reported. Dichloroacetic acid was used as the cosolvent for blending. PEEK and PEI are confirmed to be miscible in the melt. The glass transition,Tg, behavior obeys the simple Fox equation or the Gordon‐Taylor equation with the adjustable coefficientk= 0.86. This agrees with prior data on melt‐blended PEEK/PEI blends. TheTgwidth of the amorphous PEEK/PEI blends was found to be broader than that of the pure components. The maximum broadening is about 10°C. The specific volume of the amorphous PEEK/PEI blends shows a slight negative deviation from linearity, indicating favorable interaction between PEEK and PEI. The spherulitic growth and resultant blend morphology at 270°C were studied by a cross‐polarized optical microscope. The radial growth rate of PEEK spherulites formed from the miscible melt at 270°C decreases from 3.04 μm/min for PEEK/PEI 90/10 blend to 0.77 μm/min for PEEK/PEI 70/30 blend. The decrease in crystalization rate of PEEK from PEEK/PEI blends is attributable to the increase in blendTg. A linear growth was observed for PEEK spherulites formed from miscible melt at 270°C in the early growth stage. The spherulitic growth deviated from linearity in the late stage of growth. PEEK spherulites formed from the miscible PEEK/PEI melt at 270°C are essentially volume‐filling. The branches of the spherulites become more clear for PEEK spherulites formed from the blend than that formed from pure PEEK melt.
Development of crystallinity in NEW‐TPI polyimide
Authors: Friler Jerome B. , Cebe Peggy
Published: December 2004

Development of crystallinity in NEW‐TPI semicrystalline polyimide has been studied using differential scanning calorimetry (DSC), wide (WAXS), and small angle X‐ray scattering (SAXS). Crystallinity of the fully imidized powder, pellet, or film processed NEW‐TPI can occur from the melt, and depends upon the holding temperature of the melt. Repetitive exposure to elevated temperatures supresses the development of crystallinity from the melt state. In amorphous pellets and film, crystallinity can also develop by cold crystallization from the rubbery amorphous state. SAXS results show that during cold crystallization, NEW‐TPI develops a periodic structure consistent with formation of alternating crystalamorphous stacks, but with crystals only a few molecular repeat units thick. Kinetics of nonisothermal crystallization were studied as a function of heating rate and could be described using the Ozawa analysis. Non‐isothermal crystallization proceeds at a slower rate in NEW‐TPI than in other high temperature thermoplastics such as PEEK, and with a much narrower processing window. The maximum degree of crystallinity that could develop during heating was 0.34, which occurred at a rate of 5°C/min. Similar degrees of crystallinity could be introduced by heating amorphous NEW‐TPI film in N‐methylpyrrolidone.
Analysis of thermal stability of acrylonitrile‐acrylic elastomer‐styrene terpolymer in injection molding
Authors: Kohkame Hisashi , Asano Hideki , Goto Masao , Miyano Yasushi
Published: December 2004

Acrylonitrile‐acrylic elastomer‐styrene terpolymer (AAS resin) was developed to improve weatherability of acrylonitrile‐butadiene‐styrene terpolymer (ABS resin). To compare thermal stability of both resins, test parts of AAS and ABS resins were injection molded at various temperatures and the Izod impact value of the resulting moldings was measured. A study was then made to find the relationship between this value and deterioration of the resins. AAS resin was molded at temperatures from 180°C to 280°C. The impact value of the resulting moldings was almost constant for temperatures up to 260°C, with the first major decrease occurring at 280°C. In contrast, the impact value of conventional ABS resin moldings constantly decreased as the molding temperature was elevated. To explain this phenomenon in both resins, two types of test program steps were undertaken: (1) The cause of the change in characteristics of the AAS resin was determined by obtaining its stress‐strain curve in a high‐speed flexural strength test; measuring its infrared absorption spectrum; and determining its flow properties with a constant‐pressure extrusion type rheometer; (2) the distribution of elastomer in the resin was observed with an electron microscope. It was found that the decrease of impact values of both resins at high temperatures is caused by deterionration of the elastomer. Also, it was found that the different relationships between the impact value and molding temperatures for AAS and ABS resins are due to the difference between the rates of thermal degradation of the acrylic elastomer and butadiene elastomer.
Segmental motion of stereoregular poly(methyl methacrylates) in a homologous series of n‐alkyl acetate solvents by nmr relaxation measurements
Authors: Ryoo Byung‐Kyu , Kim Dong‐Won , Lee Jae‐Hun , Park Jung‐Ki
Published: December 2004

The 13C spin‐lattice relaxation times, T1s, of both stereoregular poly(methyl methacrylates) (PMMA) and homologous series of n‐alkyl acetate solvents in solution have been measured at 40°C. It was observed that the motion of polar side‐chains was highly affected by the degree of interaction with solvent molecules. The stronger polymer‐solvent interactions in predominantly syndiotactic PMMA solutions than in isotactic PMMA solutions were shown from the T1 values for the carbonyl, methoxy, and quaternary carbons in polymer segments and also from the carbonyl T1s of solvent molecules. By relating the solvent dependences of the T1 data in syndiotactic polymer solutions to that of the known dissolution rate data of atactic PMMA, it was found that the solvent dependences of the T1 values of those carbon groups in which the polymer‐solvent interaction is not significant, e.g., methylene and α‐methyl carbon groups, were consistent with the solvent dependence of the dissolution rate of polymer. This result suggested that the dissolution of polymer is mainly governed not by the sorption process related to the polymer‐solvent interaction but by the transport process related to the local motions of polymer segments and solvent molecules.
Rheology and structure of liquid crystalline alkylenearomatic polyesters
Authors: Kulichikhin G. V. , Dreval' V. E. , Kotova E. V. , Antipov E. M. , Godovsky Yu. K. , Zuev V. V.
Published: December 2004

The rheological, thermodynamic and structural properties of two liquid crystalline polyesters—poly(oxyfumaroyloxy‐ 1,4‐phenylene carbonyloxyalkyleneoxycarbonyl‐ 1,4‐phenylene)s with six and ten methylene groups (PES‐6 and PES‐ 10, respectively) and a statistical copolyester (co‐PES) have been investigated. It has been shown that they all form a smectic LC‐phase. The change from homopolyesters to co‐PE S expands the temperature range of the LC‐state. The high sensitivity of the structure to the prehistory in the melt state is typical for such copolymers. Prolonged heating leads to rearrangement of the co‐PES crystalline structure and a drastic increase in viscosity. The orientation of these polymers during flow was investigated. It was shown that a high level of molecular orientation of the smectic layers, perpendicular to the direction of flow, was realized at high shear stresses. In the melt region, the existence of a metastable network with junctions of crystalline nature hinders the flow of the homo‐ and copolyesters. The structure of the unit cell of the crystallites depends on the composition and thermal history.
A method for approximate prediction of extrudate swell
Authors: Bush M. B.
Published: December 2004

The extrudate swell problem is modeled as the stratified flow of two Newtonian isothermal fluids with differing viscosities. If the viscosity of the thin outer layer is the greater of the two, then enhanced swelling relative to the case of equal viscosity is observed. By suitable selection of the the viscosity ratio, this model can be used to represent thermal, shear‐thinning, and elastic effects in extrusion. The stratified flow problem is solved using an efficient boundary element method. The model then provides a means of studying and predicting complex geometrical effects in profile extrusion without the burden of a full viscoelastic solution, which may yield a practical aid to the die design process.
The evolution of material properties during physical aging
Authors: McKenna Gregory B. , Leterrier Yves , Schultheisz Carl R.
Published: December 2004

Aging experiments using the NIST (National Institute of Standards and Technology) torsional dilatometer have been performed in which the temperature of an isothermally equilibrated epoxy glass was abruptly changed to a new temperature T0 and the evolution of the volume and torsional relaxation responses recorded. The results of down‐jump and up‐jump experiments were found to differ dramatically. Not only is the normal asymmetry of volume approach to equilibrium found, but the mechanical responses are found to evolve differently from the volume response, contrary to simple free volume models of the physical aging process. It is found that the torsional modulus changes with increasing time after the T‐jump. In the case of the down‐jump the evolution of the modulus ceases prior to that of the volume of the sample. In the up‐jump experiment, the contrary is true, viz., the modulus continues to evolve after the volume has attained its equilibrium value. The implications of this for the description of material behavior are discussed.
Enhanced polycarbonate toughness. I: Measurement methodology
Authors: Kim S. W. , McGarry F. J. , Riew C. K.
Published: December 2004

The JIC values for core‐shell‐particle‐toughened polycarbonate were determined at different temperatures and at 0, 2.5, 5.0, 7.5, and 10.0 phr particle content by six similar methods, using compact tensile specimens. At the 2.5 phr toughener level, the JIC values ranged from 2878 to 6100 J/m2, and at 7.5 phr, they ranged from 6125 to 10,760 J/m2, dependent only upon how the same JI‐Δ a data were interpreted. This indicates that more work will be required before a reliable method of JIC measurement that can be applied to tough polymers is achieved.
Morphology and mechanical properties of liquid crystalline copolyester and poly(ethylene 2,6‐naphthalate) blends
Authors: Jang Sang Hee , Kim Bong Shik
Published: December 2004

Blends of poly(ethylene 2,6‐naphthalate) (PEN) and a liquid crystalline copolyester (LCP), poly(benzoate‐naphthoate), were prepared in a twin‐screw extruder. Specimens for mechanical testing were prepared by injection molding. The morphology and mechanical properties were investigated by scanning electron microscopy (SEM) and an Instron tensile tester. SEM studies revealed that finely dispersed spherical domains of the liquid crystalline polymer (LCP) were formed in the PEN matrix, and the inclusions were deformed into fibrils from the spherical droplets with increasing LCP content. The morphology of the blends was found to be affected by their composition and a distinct skin‐core morphology was found to develop in the injection molded samples of these blends. Mechanical properties were improved with increasing LCP content, and synergistic effects have been observed at 70 wt% LCP content whereas the elongation at break was found to be reduced drastically above 10 wt% of LCP content. This is a characteristic typical of chopped‐fiber‐filled composites. The improvement in mechanical properties is likely due to the reinforcement of the PEN matrix by the fibrous LCP phase as observed by scanning electron microscopy. The tensile and modulus mechanical behavior of the LCP/PEN blends was very similar to those of the polymeric composite, and the tensile strength and flexural modulus of the LCP/PEN 70/30 blend were two times the value of PEN homopolymer and exceeded those of pure LCP, suggesting LCP acts as a reinforcing agent in the blends.
Rubber modified epoxy resin. III: Reaction injection molding process
Authors: Kim Dae Su , Kim Sung Chul
Published: December 2004

Reaction injection molding of amine terminated butadiene acrylonitrile copolymer (ATBN) modified epoxy resin was investigated through computer simulation and experiment. The epoxy system composed of diglycidyl ether of bisphenol A (DGEBA) and triethylene tetramine (TETA) was employed since this system indicated a relatively high reaction rate. The coupled balance equations of momentum, chemical species, and energy within the disc‐type mold cavity were solved using finite difference techniques. The predicted temperature and conversion profiles within the mold were compared to experimental results. The domain correlation length data calculated from the simulation model were compared with the results of SEM micrographs. A moldability analysis was performed to find the optimum molding conditions. The moldability window decreased as the mold thickness was increased.
Analysis of shrinkage by dual kriging for filled and unfilled polypropylene molded parts
Authors: Mamat A. , Trochu T. F. , Sanschagrin B.
Published: December 2004

This paper examines, through holding pressure, packing time, melt temperature, mold temperature and distance from the gate, the effect of molding conditins on the shrinkage of polypropylene and 40% calcium carbonate (CaCO3) filled polypropylene. The shrinkage longitudinal and transvrse to the flow direction were determined using a 127 × 76 × 4 mm thick plaque with a film gate. Marks were made ont he mold cavity to measure shrinkage at various distances from the gate. The results show that holding pressure and packing time are the most significant parameters. Cooling runners, however, could significantly influence local shrinkage values. Calcium carbonate reduces the shrinkage anisotropy as well as the cycle time of the molded parts. Shrinkage models have been developed using dual kriging statistical interpolation techniques and show an excellent fit with experimetnal data.
Origin of the intermediate damping peak in microlayer composites
Authors: Nazarenko S. , Haderski D. , Hiltner A. , Baer E.
Published: December 2004

A comparison of glass transition temperatures measured by differential scaning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) was made using mi9crolayer composites with many alternating layers of two polymers. What appeared to be a third transition at a temperature intermediate between the glass transitions of the two components was observ ed in DMTA but not DSC. The mechanical orgin of this intermediate damping peak in the layered composites was established. The viscoelastic properties of each polymer were modelled by a spring and dashpot in series, and the composite as a parallel arrangement of two Maxwell elements. It was shown that an anomalous damping peak can appear between the glass transition temperatures when the modulus of the composite can not drop below the modulus of the glassy layers, although the viscosity of the composite continues to be defined by the viscosity of the rubbery layers in this temperature range. The intermediate damping peak may be a general feature in the dynamic mechanical behavior of co‐continuous multiphase systems including polymer blends and continuous fiber composites.
The hybrid FEM/FDM computer model for analysis of themeteirng section of a single‐screw extruder
Authors: Chang Rong‐Yeu , Lin Kuen‐Jang
Published: December 2004

A hybrid FEM/FEM computer model was employed n this studyfor simulating the non‐newtonian, nonisothermal polymr melt fielt in the inetering section of a single‐screw extruder. The pressure distribution in the screw surface was obtained by solving the generalized Reynolds equation. Instead of using the energy equation in Eulerian frame, a Lagrangian expression ws involved for stabilizing the numerical scheme. The temperature profiles wee obtained by finite difference discretizaton for the energy equation in such element. The screw surface with the screw channels and the flight lands could be modeled as a surface divided into small shell elements. To demonstrate aplicability, the results provided by the hybrid FEM/FDM were found to be similar to those of the 2D FDM for the trhermally developing flow, through Fenner's example. It can also ilustrate the leakage flow and the cross‐channel effect in the screw pumping problem. The results from the Hybrid FEM/FDM revealed that if the clearance becomes too large, the volumetric flow rate would considerably decrease and the exist melt temperature would increase. In addtion, when the clearance is close to the normal design clearance, the leakage flow through the flight lands was found to be small. These computational results were observed to correlate with those of other experimental studies. Finally, the hybrid FEM/FDM approach can in principle be extended to the non‐Newtonian, nonisothermal flow in a complex screw surface such as the barrier screw and the Maddock mixing head.
Assessment of residual stresses during cure and cooling of epoxy resins
Authors: Wang Hong‐Bing , Yang Yu‐Geng , Yu Hui‐Hong , Sun Wei‐Ming , Zhang Ying‐Hua , Zhou Hong‐Wei
Published: December 2004

A new stress monitoring technique, a stress‐tracking device, is described here. It has been used to study some important properties of epoxy resin. Residual stresses, including a curing shrinkage stress and a cooling shrinkage stress, were measured automatically and continuously during curing and cooling. Simultaneously, information such as an apparent gelation time and glass transition temperature were obtained directly during the experiment. These epoxy resin properties were related to the extent of cure. Varying cure temperature produced changes of cure behavior, which resulted in different residual stresses.
Creep analysis of thermiplastics using stress relaxation data
Authors: Grzywinski G. G. , Woodford D. A.
Published: December 2004

One of the major factors limiting the use of thermoplastics in engineeing applications is the inadequacy of existing design data. Much of the data do not span appropriate ranges of stress, strain, time, or temperature. This study addresses the need to develop an accelerated method for generating long‐time design data to support the innovative use of engineering thermoplastics. In particular, stress relaxation tests (SRT) were performed on polycarbonate (PC) and midified poly(phenylene oxide)(PPO), and used to generate time‐dependent design data through the short‐time measurement of the material's current state without dependence on elastic modulus. The test results and analyses reported here indicate the SRT method to be an efficeint means of generating accurate and repeatable creep and secant modulus data which may be directly used in design. Therefore, SRT shows great potential both as a design parameter development tool, and as a quality control instrumetn for assessing batch‐to‐batch variability.
Thin‐film thermoplastic‐metal joining process for titanium to poly(etherketoneetherketoneketone)
Authors: Ramani Karthik , Tagle John , Nazre Ajit , Swarts Dale , Lin Steve
Published: December 2004

The processing of high temperture thermoplastic polymers as a hot melt adhesive is one means of joining thermoplastics to metals. The presetn study establishes the role of processing in thermoplastic joining of a titanium alloy (Ti‐6A1‐4V) using thin flim poly(etherketoneetherketoneketone) (PEKEKK). A design of expriments (DOE) was performed to determine the effects of the soak above melt temperature (Tm = 380°C), hold at the isothermal recrystallizztion temeprature (Tiso = ∼ 340°C) and cooling rates on the joint strength, Extended soak times are required to remove the residual spherulitic crystallinity in the polymeric adhesive. Whit the elimination of the residual crystallinity, high‐strength transcrystalline regions are enhanced at the polymer‐metal interface during the hold time at Tiso and during cooling to ambient temperature. Average tensile strengths of 137 MPa were achieved, exceeding the bulk polymer tensile strength of 118 MPa by 16%, X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) show that extended soak times above Tm led to excessive polymer squeeze‐out, resulting int he creation of strength‐reducing shrink voids or unwetted regions. As a result, the failue mode of the joint, which was normally cohesive for high‐strength joints, became a mix of cohesive and adhesive in parts with excessive polymer squeeze out.
Philanthropy and fundraising in Western Europe within a framework of change
Authors: Heinzel Helmut
Published: December 2004

The highly developed third sector in Western Europe is suffering from shrinking government funding. Dynamic nonprofit organizations are finding new private sources for funding as they develop new techniques in fundraising.
Wettability and Dyeability Modulation of Poly(ethylene terephthalate) Fibers through Cold SF6 Plasma Treatment
Authors: Barni Ruggero , Riccardi Claudia , Selli Elena , Massafra Maria Rosaria , Marcandalli Bruno , Orsini Francesco , Poletti Giulio , Meda Laura
Published: December 2004

Summary: Surface modification induced on poly(ethylene terephthalate) (PET) fibers by cold SF6 plasma treatment has been investigated systematically as a function of plasma device parameters. The observed wettability modifications of fibers plasma‐treated under different operating conditions were correlated to their dyeability modifications and to the changes in surface chemical composition, determined by X‐ray Photoelectron Spectroscopy (XPS), and topography, investigated by atomic force microscopy (AFM). Optical emission spectra from the SF6 plasma at different pressures gave information on its content of fluorine atoms. A striking transition was observed between the increased hydrophilicity and high dyeability, imparted by plasma treatment at low pressure (<0.2 mbar), mainly as a consequence of surface etching and surface activation, and the increased hydrophobicity, imparted by plasma treatment in the higher pressure regime (0.2–0.4 mbar), consequent to extended surface fluorination.

Water droplet adsorption time on PET fabrics, plasma‐treated at different pressures.

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Water droplet adsorption time on PET fabrics, plasma‐treated at different pressures.
Forward Scattering Signature of a Spherical Particle Crossing a Laser Beam out of the Beam Waist
Authors: Chevaillier Jean‐Philippe , Fabre Jean , Hamelin Patrice , Lense Jean‐Loup
Published: December 2004

When a particle crosses a laser beam out of the focal plane, the light attenuation signal occuring on the beam axis contains some information regarding the particle size and trajectory.

These attenuation signatures are analysed and predicted with a simplified model based on Fraunhofer diffraction. Numerical and experimental results are found to be in good agreement.

A modified laser Doppler velocimeter using this sizing method is able to perform simulataneous measurement of size and velocity of spherical particle in the range 10 μm–500 μm.
The Phase‐Doppler‐Difference‐Method, a New Laser‐Doppler Technique for Simultaneous Size and Velocity Measurements. Part 1: Description of the method
Authors: Bauckhage Klaus
Published: December 2004

In the wide field of fluid mechanics and multiphase flows, particle characterization plays an important role for massmomentum‐ and energy‐balances. Using the phase‐Doppler‐difference method for absolute measurements of the particle sizes and velocities from these data also predictions of the local particle fluxes and the particles' kinetic energy fluxes are possible. A description of the method will be given and the required optical and electronical equipment for these measurements and for the appropriate data presentation, will be discussed.
Demonstrating the Sampling of Heterogeneous, free‐flowing, segregating powders
Authors: Hawkins Arthur E.
Published: December 2004

Experiments with common powder laboratory apparatus are used to illustrate the problems of sampling a poorly mixed quantity of glass ballotini. The use of known and easily sieved mixtures permits the quantitative analysis of the results to show how bias in samples may be detected.
In‐line Particle Size Analysis in the fines outlet of an air classifier
Authors: Heuer Michael , Schwechten Dieter
Published: December 2004

Laser diffraction (LD), with reference to the analysis time, is highly advantageous for the automation of particle size analysis. The high measuring frequencies alloy quasi‐continous measuring operation. The fineness values obtained form the particle size distribution (PSD) can be transformed into electrical signals for automatic process control.

For industrial purposes, an encapsulated measuring cell was developed where the laser beam penetrates the dispersed fines stream via two optical windows. Thus, hazardous materials can also be measured, specifically pharmaceutical or chemical products, or applications requiring explosion‐proof plant design are possible. Great efforts had to be made to keep the inner side of the windows clean form product dust. Ultimately, batches running for more than 8 h could be analysed continuously without any contamination of the windows. For the PSD measurements, a standard LD instrument was used with a measuring range of 0.5/0.9–175 μm.

As product fineness is monitored continuously in‐stream, and virtually without delay, any changes in the fineness during classifier operation can be detected immediately. On the one hand, this opens up a new field for studies of classifier performance. On the other, immediate quality control of even very small batches is possible during the micronization process. The results demonstrate very clearly, for example, the importance of controlling the feed rate to the classifier. Therefore, fineness control by means of this in‐line technique gives superior advantages for direct adjustment of the classifier speed.
Experimental Determination of the Transfer Function of a Differential Mobility Analyzer (DMA) in the nanometer size range
Authors: Hummes Detlef , Neumann Siegfried , Fissan Heinz , Stratmann Frank
Published: December 2004

This paper describes the evaluation of the transfer function for the TSI‐short differential mobility analyzer (DMA) in the nanometer particle size rang. The TSI‐short DMA is identical with the TSI‐long DMA (Model 3071) but has shortened inner and outer electrodes and the insulator material Teflon was replaced by black Delin. The DMA transfer function was determined by operating two identical DMAs in series. The DMA was investigated at a sheath to aerosol flow rate ratio of between 10 and 1. Usually for particles above 50 nm the parameters of the assumed triangular transfer function, i.e. height and half‐width, approach the ideal values, which depend only on the flow ratio. For particle size below 50 nm the height decreases from 0.9 at 50 nm to 0.18 at 5 nm. The half‐width increase from the ideal value 0.1 to about 0.17. The observed changes of the transfer function are due to diffusional effects resulting in losses mainly in the inlet and outlet and also broadening of the aerosol stream inside the DMA. The determined transfer functions were also compared with transfer functions calculated using a theoretical model. The agreement proved to be satisfactory. The half‐widths and the transmission efficiencies of the conventional TSI‐DMA (Model 3071), TSI‐short with Teflon and also black Delin insulator as a function of particle size are compared to demonstrate the improvements in performance.
Ostwald Ripening of Concentrated Alkane Emulsions: A preliminary report
Authors: Bremer Leon , De Nijs Bruno , Deriemaeker Luc , Finsy Robert , Geladé Erik , Joosten Jacques
Published: December 2004

Fiber optic dynamic light scattering (FODLS) was used to study the kinetics of aging processes in emulsions of n‐alkanes stabilized by a surfactant. The method is particularly useful for this purpose because it permits measurements in concentrated emulsions. Complications that may occur in traditional DLS due to the extreme dilution, such as solubilization of the particles in the medium, can be easily avoided in this way. The experimental results show that the main aging process is Ostwald ripening. The results are in agreement with theoretical predictions based on the Lifshitz‐Slyozov‐Wagner (LSW) theory as far as it concerns the relation between the molecular solubility of the n‐alkanes (in the aqueous phase) and the Ostwald ripening rate. This illustrates that the main rate‐determining factor is the molecular diffusion of the alkane molecules through the continuous (aqueous) phase. The Ostwald ripening rate is affected by the concentration of surfactant but in all situations is higher than expected from LSW theory.
The Use of Lead in Explosive Cladding
Authors: Prümmer R.
Published: December 2004

Lead has for a long time not been employed in explosive cladding because its velocity of sound (c = 1250 m/s) is very low compared to the detonation velocities of conventional explosives (vD ≈ 3000 m/s). I t is shown that by using a carbonite explosive, which has a detonation velocity of less than 1500 m/s, useful explosive cladding can be achieved. The relationship between quantity of explosive and cladding parameters such as angle of collision and plate velocity vp is determined. The interface between lead‐copper and lead‐steel claddings is wave‐like. The wavelength depends on the angle of collision and is larger for lead‐copper claddings than for those between lead and steel.
Electrical Conduction in Ammonium Perchlorate
Authors: Pai Verneker V. R. , Mohan V. Krishna
Published: December 2004

Electrical conductivity studies on pure ammonium perchlorate, AP, and AP doped with sulphate ions have been carried out. The results indicate that the conduction is ionic in nature. Together with the observations made on the effect of electric field on the thermal decomposition of AP, the results of the present study establish that perchlorate ion is the major charge carrying species. The enthalpy for migration of defects has been found to be 0.8 eV, and the enthalpy for the formation of defects to be 1.2 eV.
Recovery of Organic Values from TNT Purification Waste Water
Authors: Gilbert E. E.
Published: December 2004

Pure sodium 2,4‐dinitrotoluene‐3‐sulfonate and ‐5‐sulfonate were prepared, and a procedure was developed for their extraction (as a mixture) from TNT purification waste water (‘red water’). Reactions of the sulfonates were studied, with special emphasis on possible direct and indirect methods for desulfonating them to 2,4‐DNT. Other reactions studied included reduction of one or both nitro groups, followed by desulfonation, yielding 2‐amino‐4‐nitrotoluene and 2,4‐diamino‐toluene, respectively, and replacement of the sulfonate group by chlorine, hydroxyl, and various substituted amino groups. Most of these reactions with the pure sulfonates were also applied to the corresponding TNT isomers, and in some cases directly to stabilized red water.
Laboratory and Field Investigations of Shotfiring Fumes of mining explosives in Poland
Authors: Cybulska R. , Sobala J.
Published: December 2004

Detonation products of basic explosives like ammonium nitrate, permitted Metanit D 2 and nitroglycerin‐Barbaryt A were analysed for O2, CO2, CO, CH4, H2, NO2 and N2 and the shotfiring properties studied. The tests were carried out under laboratory conditions and in shotholes drilled underground in the mine, in coal and in stone.
Die in der Bundesrepublik Deutschland benutzte Methode zur Bestimmung der toxischen Bestandteile der Sprengschwaden
Authors: Eitz E. , Zimmermann R.
Published: December 2004

Bei der Zulassungsprüfung von Bergbausprengstoffen werden Sprengschwaden mit einer praxisnahen Sprenganordnung in einer Gesteinskammer der Versuchsgrube Tremonia erzeugt. Der Gehalt der Sprengschwaden an den toxischen Bestandteilen Kohlenmonoxid und nitrose Gase wird nach vorgeschriebenen Probenahme‐ und Analysenverfahren ermittelt. Die Einzelheiten der Methode werden beschrieben. Zusätzlich wird über Untersuchungen zur Erzeugung von praxisähnlichen Sprengschwaden in einer Laboratoriumsanordnung berichtet.
Eine Methode zur Prüfung der Detonationsfähigkeit von Slurries
Authors: Klünsch M. , Lingens P.
Published: December 2004

Es wut Je eine Prüfmethode für die Detonationsfahigkeit von Sprengschlammen entwickelt, die sowohl die Bestimmung des kritischen Durchmessers als auch der kritischen Zündladung erlaubt. Außerdem ermöglicht diese Methode eine Brisanzmessung zur Unterscheidung unterschiedlicher Sprengschlamme. Die Prufmethode beruht auf dem Beschuß einer Stahlplatte. Der Sprengstoff befindet sich in einem Stahlrohr, das senkrecht auf die Beschußplatte gestellt wird. Der Sprengstoff wird mit Hilfe einer Verstärkerladung von oben her gezündet. Der Eindruck oder Durchschlag auf der Stahlplatte erlaubt eine Beurteilung des geprüften Sprengschlammes. Die Prufmethode macht es moglich, Sprengschlamme miteinander zu vergleichen und für den Einsatz in der Praxis auszuwählen.
Erfahrungen mit Methoden zur Einordnung der Deflagrationsfestigkeit von Wettersprengstoffen
Authors: Zimmermann R.
Published: December 2004

Zur Ermittlung der Deflagrationsfestigkeit von Wettersprengstoffen höherer Sicherheitsklassen wird in der Bundesrepublik Deutschland eine Variante des von Audibert und Delmas vorgeschlagenen Verfahrens benutzt (geschlossenes Stahlrohr mit Entlastungsdüse). Dabei wird die Deflagrationsneigung des Sprengstoffs unter Druck‐ und Wärmestau in einer Kohlenstaubumgebung bestimmt. Die Einleitung der Deflagration erfolgt durch einen definierten Anzündsatz. Die Druck‐ und Wärmestau‐Bedingungen werden durch eine Düse wählbaren Durchmessers vorgegeben. Bei den nach diesem Verfahren geprüften und zugelassenen Wettersprengstoffen ist in der Praxis seit 1972 kein Fall einer Deflagration bekannt geworden.
Génération et Repérage d'un Signal Lumineux Bref
Authors: Presles H. N. , Bouriannes R. , Brochet C.
Published: December 2004

Résumé

On présente une méthode simple de génération et d repérage d'un signal lumineux. Ce signal est obtenu en ionisant un petit volume d'argon par une onde de choc forte. Il est repéré dans le temps à l'aide d'un signal électrique provoqué par la polarisation d'un matériqu diélectrique traversé par cete même onde de choc. Ce dispositif est utilisé pour déterminer le temps de retard d'un pyromètre optique à court temps d réponse.
The assay of hydrazine mononitrate as a base in acetic acid
Authors: Selig W. , Bissell Eugene R.
Published: December 2004

Hydrazine mononitrate has been determined as a base by non‐aqueous titration in glacial acetic acid. The titrant was 0.05 N perchloric acid in glacial acetic acid which must be prepared without acetic anhydride. Small amounts of water increase the solubility of hydrazine nitrate, but reduce the sensitivity of the method.
Detonation chemistry: Diffusion control in non‐ideal explosives
Authors: McGuire R. R. , Ornellas D. L. , Akst I. B.
Published: December 2004

The performance of an explosive is a function of both the peak energy released near the detonation front, and the remainder of the energy that is released during the Taylor wave. The relative partitioning of energy between the front and the expansion, and the rate of energy release in the latter, may be controlled by either chemical kinetic or diffusion processes. Detonation calorimetry has been the principal experimental technique used to investigate these processes. Both the total energy release, and the quantitative analysis of the detonation products at a point or region on the expansion isentrope have been determined for formulations of ammonium nitrate (AN) and TNT in which both the composition and particle size of the AN have been varied. Isotopic labeling of selected explosives has also been used to give further insight into the reactions taking place in or near the reaction zone. Similar experiments have been performed in an ideal, homogeneous explosive.
Accelerated Aging of a Composite Explosive
Authors: Perrault G. , Béadard M. , Lavertu R. R. , Tremblay M.
Published: December 2004

A given formulation of a composite explosive was submitted to accelerated aging at 293 K, 333 K and 353 K for slightly over a year. Extensive determination of mechanical properties were conducted using an Instron Tester to characterize the aging process of the explosive as a whole. The change of elongation at maximum load can be fitted to a third‐order reaction rate giving an enthalpy of activation (Δ Ha) for the aging process of (78 ± 5) kJ/mol. Although the change of stress at maximum load was a function of temperature, it could not be predicted by a simple correlation. Swelling, inverse gas chromatography and N2O evolution by infrared were applied to the samples aged at 333 K. Swelling measurements show a regular increase with aging of the relative number of cross‐linking. Inverse gas chromatography at 373 K in helium indicated a first‐order kinetic aging process for every sample, but the rate constant (k) of the samples aged for 0, 30 and 60 days was slightly lower than the one for samples aged for 130, 250 and 375 days. The N2O evolution measured at 338.5 K in vacuum by infrared absorption indicates an aging process consisting of two consecutive first‐order reactions, the second one being ten times slower than the first one. The first stage, which was also studied by inverse gas chromatography, gives rate constants which are about half as large as those measured by chromatography and confirms the changes in behavior from the samples aged for 0, 30 and 60 days to the samples aged for 130, 250 and 375 days. These results are discussed in relation to an aging process by oxidative cross‐linking of the binder and degradation of the solid explosive.
Form Function for Propellants in Closed Vessel Work
Authors: Vittal D. , Singh S.
Published: December 2004

A general theoretical cubic form function for use in closed vessel work during the evaluation of absolute ballistic parameters of propellants is introduced along with the expressions for the coefficients for a number of common propellant shapes. The conditions under which this form function is accurately applicable are also indicated. This form function is superior and gives much more accurate results than the quadratic form function which is in wide use at present. The differences of the cubic form function from the quadratic are also explained.
New adducts of 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX)
Authors: Selig W.
Published: December 2004

Relatively stable equimolar adducts of 1,3,5‐trinitro‐1,3,5‐triazacyclohexane were prepared with 2,6‐lutidine‐N‐oxide, 4‐hydroxy‐1‐butanesulfonic acid δ‐sultone (1,4‐butane sultone), and 2,2,6,6‐tetramethyl‐4‐piperidone‐1‐oxyl. Only the last adduct is selective for RDX; the others also form adducts with 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazacyclooctane. A very labile RDX adduct is formed with tetrahydrothiophene‐1‐oxide. Some properties of the new adducts are presented.
Experimental study on the performance of pyrotechnic igniters
Authors: Klingenberg G.
Published: December 2004

A special igniter case designed by Dynamit Nobel AG was used for measuring the energy output of four different igniter formulations in terms of gas pressure, flame temperature, and gas velocity in order to study the performance of pyrotechnic igniter systems, and to evaluate the energy flux at the igniter vent. Four igniter systems were defined which consisted of (a) B‐KNO3, (b) black powder, (c) nitrocellulose, and (d) mixtures of nitrocellulose with black powder. Firings into open air, propellant dummy loads, and propellant beds were carried out with these igniters to obtain their general characteristics. It has been found that the vent characteristics of these pyrotechnic igniters are determined by the confinement conditions used. The energy flux at the igniters vent increased considerably for firings into inert or active propellant beds.
Use of NMR spectrometry for studying the acetolysis of hexamethylenetetramine III. The reaction between hexamethylenetetramine and acetic anhydride to form TRAT
Authors: Shaofang Wang , Ju Chen , Fuping Li
Published: December 2004

The acetolysis of hexamethylenetetramine (HA) to form 1,3,5‐triacetyl‐1,3,5‐triazacyclohexane (TRAT) has studied by NMR. It was found that this reaction experienced two different courses. HA turned to TRAT through the intermediate 3,7‐diacetyl‐1,3,5,7‐tetraaza‐[3.3.1]‐bicyclononace (DAPT), and HA converted at first to an intermediate M1, which gave TRAT through another intermediate M2 in the presence of water. Based on the 1H and 13C spectra, the change in the spectra with reaction and the possibility of reaction, we assumed both the structure of M2 and its reaction mechanism.
The Rheological Properties of Plasticized Nitrocellulose as a function of nitrocellulose precursor
Authors: Baker F. S. , Healey M. J. , Privett G.
Published: December 2004

Propellant cords have been manufactured from nitrocellulose/nitroglycerin (50/50) pastes containing different types of nitrocellulose. The cords were manufactured using a solvent wet process involving incorporation and extrusion in the highly instrumented propellants processing facility at Waltham Abbey. It has been shown that the biological source from which the nitrocellulose is manufactured (wood or cotton) has a significant influence upon the dough rheology, cord diameter, shear heating and ultimate tensile strength of the dried cords. Additionally, the influence of extrusion rate upon the above parameters has been highlighted. This work compliments that previously undertaken upon the influence of nitrocellulose molecular weight on the properties of propellant doughs and dried cords.
Detonation sensitivity of liquid nitromethane doped with methyl nitrite
Authors: Engelke R. , Earl W. L. , Storm C. B.
Published: December 2004

It has been suggested, by other workers, that the isomerization of normal nitromethane (NMCH3NO2) to methyl nitrite (CH3ONO) is an important first step in the chemical kinetics of liquid NM detonation. We examine this idea by studying the effect of direct methyl nitrite addition on NM's detonation sensitivity. Failure diameter is used as the measure of sensitivity. A comparison is made between the effect of methyl nitrite addition and that of a known sensitizer of NM i.e., the NM aci ion (CH2NO2−). Methyl nitrite is found to be an ineffective sensitizer relative to NM's aci ion.
Effect of Moving Plate on Jet‐Penetration
Authors: Yadav H. S. , Kamat P. V.
Published: December 2004

Effect of a moving plate between a shaped charge jet and the target on jet‐penetration has been investigated theoretically. It has been assumed that the plate moves undeformed with uniform velocity, and jet‐penetration in the plate or the target occurs hydrodynamically so that the impact of the jet produces a hole in the plate whose diameter is bigger than that of the jet. The free passage of the jet through this hole is intercepted when the jet touches the wall of the hole due to its transverse motion. The presence of a moving plate between the jet and the target has been found many times more effective than that of a stationary plate in reducing the jet penetration in the target. The effect of angle of attack, velocity of the plate and initial distance between the plate and the target on penetration, produced by the jet going out of the plate, has been investigated for a typical set of arbitrarily selected values of jet and plate parameters.
The Density Distribution in Pressed Charges. An analytical approach
Authors: Saßmannshausen U. , Essig W. , Osswald T. A.
Published: December 2004

High performance shaped charges require a perfect rotational symmetry and homogenity in structure. Therefore the density distribution of the explosive inside the charge has to meet the same specifications in order to obtain the desired geometry of the detonation wave. In this paper we present an analytical model which describes the density inside the charge as a function of the pressure and the friction between the tool surface and the granulate. The density distribution inside a cylindrical body has been calculated. The comparison with experimental data shows a good agreement.
Analysis of the initial stages of the Thermal Decomposition of 1,4‐Butanediammonium Dinitrate
Authors: Quirke J. M. E. , Fu J. , Hardy K. A. , Sheldon J. W. , Doolittle F. G. , McKenney R. L.
Published: December 2004

The initial stages of the decomposition of 1,4‐butanediammonium dinitrate (BDD) were investigated using a molecular beam sampling time‐of‐flight‐quadrupole mass spectrometer system. Experimental results are consistent with the hypothesis that the compound undergoes dissociation into 1,4‐butanediamine and nitric acid. Standard electron impact ionisation and fast atom bombardment mass spectrometric analyses of BDD gave support to the molecular beam study.