bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of fast‐cure resins for reaction injection molding
Authors: Osinski J. S.
Published: December 2004

The interest in reaction injection molding of urethane and non‐urethane resins has generated a need for a greater understanding of the molding behavior of these reactive systems. The kinetics and rheology of a given resin must therefore be well characterized in order to understand and model the molding process. This often requires semi‐empirical correlations rather than strict theoretical considerations. A method of fully characterizing such systems by combining adiabatic reactor and IR studies with viscometer data is therefore described. This results in time‐temperature‐conversion‐viscosity correlations which can be directly utilized in molding studies. Such methods are applied to polyurethane and epoxy systems in the work presented here. It was found that very different activation energies are obtained for the same epoxy‐amine system using different kinetic characterization techniques.
The effect of pressure and temperature on time‐dependent changes in graphite/epoxy composites below the glass transition
Authors: Mijović Jovan , Liang R. C.
Published: December 2004

Effects of pressure and temperature on time‐dependent changes in physical/mechanical properties of graphite/epoxy composites were investigated. Samples were cut from the eight‐ply‐thick laminates of commercially used composites, post‐cured, and then quenched to environments of various temperature and pressure. Time‐dependent changes in their properties were analyzed by thermal and thermomechanical (dynamic mechanical) measurements. An increase in the glass‐transition temperature was found to occur as a function of time. The rate of this process was enhanced by an increase in temperature and/or a decrease in pressure. An explanation was offered in terms of types and mechanisms of molecular events that occur in the glassy state. Time dependent decrease in free volume (and enthalpy) takes place but is not the sole mechanism responsible for the observed increase in Tg. After a certain period of time (which depends on T and P of the environment), additional crosslinking appears to take place.
Dynamic X‐ray diffraction studies of spherulitic poly‐alpha‐olefins in relation to the assignments of alpha and beta mechanical dispersions
Authors: Kawai Hiromichi , Hashimoto Takeji , Suehiro Shoji , Fujita Ken‐Ich
Published: December 2004

The dynamic tensile deformation mechanism of spherulitic poly‐alpha‐olefins, high‐density polyethylene, isotactic polypropylene, and isotactic polybutene‐1, was investigated by dynamic X‐ray diffraction at various temperatures and frequencies in order to assign the α and β mechanical dispersions explicitly. The uniaxial orientation distribution function qj(ζj, 0) of thej‐th crystal plane and its dynamic response Δqj′(ζj, 0) in‐phase with dynamic strain were observed for several crystal planes, and then the orientation distribution function ω(§, 0, η) of crystallites (crystal grains) and its dynamic response Δω′(§, 0, η), also in‐phase with the dynamic strain, were determined by a mathematical transformation procedure proposed by Roe and Krigbaum on the basis of the Legendre addition theorem. The temperature and frequency dependences of Δω′(§, 0, η) were analyzed in terms of a spherulite deformation model combining affine orientation of crystal lamellae with several types of preferential reorientation of the crystal grains within the orienting lamellae. The following assignments are made: (1) the a mechanical dispersion must be assigned to the dynamic orientation dispersions of crystal grains within lamellae involving two types of preferential rotations of the grains associated with lamellar detwisting mostly in the equatorial zone of uniaxially deformed spherulites and with lamellar tilting mostly in the polar zone of the spherulites. Both processes are intralamellar grain‐boundary phenomena, and the former process of lamellar detwisting is hardly activated for polypropylene and polybutene‐1 spherulites in contrast to polyethylene spherulites. (2) The β mechanical dispersion must be assigned to the dynamic orientation dispersion of the crystal lamellae behaving as rigid bodies unaccompanied by reorientation of crystal grains within the orienting lamellae. This process is an interlamellar grain‐boundary phenomenon.
Orientation studies of poly(ethylene terephthalate)
Authors: Jabarin Saleh A.
Published: December 2004

This paper discusses the results of a detailed study of the relationships between molecular orientation, physical properties, and molecular weight of polyethylene terephthalate (PET), and their dependence on orientation variables. The molecular weight range of the samples used in this study included weight average molecular weights,Mw, between 29,000 and 65,000 which correspond to inherent viscosities, I.V., from 0.5 to 0.9. The orientation temperatures investigated were between 80 and 120°C. The extent of molecular ordering imparted by the orientation process was studied by birefringence, density, light scattering, and depolarized light intensity techniques. The results show that the degree of molecular orientation and the physical properties are strongly dependent on strain rate, extension ratio, molecular weight, and orientation temperature. The mechanical and transport properties, of PET are directly related to the degree of orientation as measured by birefringence. It is found that at a comparable level of orientation, the mechanical properties are also dependent on molecular weight, whereas the transport properties are independent of molecular weight. The degree of orientation varies according to the molecular weight of PET and stretch temperature. It is shown that for the same stretch ratio and stretch speed, the birefringence decreases with increasing stretch temperature. The light scattering results indicate that biaxial orientation of PET can lead to strain‐induced crystallization. The amount and form of the crystalline structures are dependent on strain rate and orientation temperature.
Rheological and mechanical properties of ternary blends of linear‐low‐density polyethylene/polypropylene/ethylene‐propylene block polymers
Authors: Dumoulin M. M. , Farha C. , Utracki L. A.
Published: December 2004

The effect of addition of an ethylene‐propylene block polymer on rheological and mechanical properties of a linear‐low‐density polyethylene/polypropylene blend was examined. The samples were prepared by melt blending in a twin‐screw extruder followed by injection molding. The single‐, two‐ and three‐component systems were treated the same way. The mechanical behavior of the blends was evaluated by means of tensile, and flexural, tests at 23 and −40°C. The capillary, elongational, and dynamic‐flow measurements were performed at 190°C.
Polymer structure: The key to process‐property control
Authors: Samuels Robert J.
Published: December 2004

The key to process‐property control is a knowledge of the structural state of the product desired and the availability of methods to economically characterize the structural states produced. The present paper demonstrates that these goals are attainable. Examples illustrate both that the equivalent state concept leads directly to the use of structural state functions as the pivotal criteria around which property and process data can be organized, and that this approach is appropriate to many fabrication processes, including films, fibers, and moldings. Further, the development of process‐structure‐property correlations is seen to lead to new processes and the development of structures having unique properties.
The effects of degree of mixing and concentration of carbon black on the tensile properties of filled elastomers
Authors: Lee Michael C. H.
Published: December 2004

Based on the concept of entropy of mixing, a new method for determining the degree of mixing of the filler in a polymer matrix has been established. The measurement used in this method is based on a new variable, the effective volume fraction of the filler, ϕ′, which is a function of the mixing index, A, and the volume fraction of the filler, ϕ. The mixing index can be determined from the tensile modulus data of filled elastomers. Excellent agreement is obtained between the mixing index and the dispersion of the filler as determined by a morphological study of cryogenically fractured surfaces of filled elastomers. Using the new variable, the effective volume fraction of the filler, useful relationships for the tensile modulus and the ultimate stretch ratio of filled elastomer have been established. Experimental data confirm that these relationships can well describe the effects of concentration and degree of mixing on the two tensile properties of filled elastomers.
A new semicrystalline reinforced polyamide engineering thermoplastic
Authors: Onder Kemal , Chen Augustin T.
Published: December 2004

A new rapidly crystallizing aromatic‐aliphatic polyamide has been developed by reacting 4,4′‐methylene bis(phenylisocyanate) (MDI) with aliphatic dicarboxylic acids. The polymer has a Tg of 130°C and Tm, of 290°C. Glass reinforced resin shows better flexural creep resistance at high stress levels (3000 psi) at elevated temperatures (75°C) than most reinforced semicrystalline commercial polymers i.e., nylons, thermoplastic polyesters and acetal because of its high Tg. Glass reinforced polyamide can be injection molded on conventional equipment to afford flexural moduli in excess of 1,000,000 psi and HDT's as high as 250°C at 264 psi. Because of the high level of crystallinity these parts will not dissolve or swell in most organic solvents and this aromatic aliphatic polyamide is also far less sensitive to moisture than commercial nylons.
Temperature measurements of polymer melts in the heating barrel during injection molding. Part 2: Three‐dimensional temperature distribution in the reservoir
Authors: Amano O. , Utsugi S.
Published: December 2004

A new method has been developed to measure the three‐dimensional temperature distribution of polymer melts in the reservoir of the heating barrel in the dynamic state. The procedure involves the use of a small‐sheathed thermocouple in the nozzle of the machine. The tip of the thermocouple can be varied in depth from the surface to the center of the nozzle. The polymer melt of a shot is found to have a three‐dimensional temperature distribution dependent on the geometry of the screw and the order of shot. These results reflect clearly the thermal histories of the polymer melt in the channel of the screw during plastication and conveyance, and indicate part of the dynamics of injection molding. Further, these measurements contribute to optimization of the design for the screw and the process conditions.
Monitoring cure in sheet molding compound processing
Authors: Castro J. M. , Straus E. J.
Published: December 2004

During the sheet molding compound (SMC) compression molding process, a premeasured polymer charge is placed between the heated halves of a mold which are then brought together to squeeze the polymer and fill the mold, after which pressure is maintained while the part cures. The cure stage constitutes the larger part of the molding cycle and thus affords the largest potential for cycle time reduction. In general, cure times in SMC processing are set longer than necessary, since the inherent material and process variation make it difficult to predict cure times with more than 10 to 20% accuracy. Accurate methods to detect the end of cure would be very beneficial and would permit opening the mold as soon as the material has cured, avoiding unnecessary waste of time. In this paper, several techniques that show promise for monitoring the state of cure are reviewed and experimental results given. Their relative advantages and accuracies are compared. In particular, the use of linear variable displacement transducers, pressure transducers, and thermocouples is discussed. We also show how the measurements compare to theoretical predictions of the state of cure.
Polyketone and complex formation of some halatopolymers
Authors: Ibidapo T. Adesanya
Published: December 2004

The possibility of a number of halatopolymers forming complexes with pyridine and their ability to produce ketones by pyrolytic decarboxylation have been investigated. Of all the halatopolymer‐forming divalent metal (i.e., Mg2+, Ca2+, Ba2+, Zn2+, Cd2+, Mn2+, and Pb2+) dicarboxylates (i.e., suberate, sebacate, dodecanedioate, and terephthalate) investigated only Cd2+ yielded polyalkylene ketone on pyrolysis and formed complexes with pyridine. The polyalkylene ketones were infusible, and no solvents were found for them which suggests a cross‐linked molecular structure. Complexes formed by the cadmium aliphatic dicarboxylates were unstable but highly viscous in solution. Cadmium‐pyridine terephthalate complexes were on the contrary very stable.
The mechanism of photocure of inherently photosensitive polyimides containing a benzophenone group
Authors: Scaiano J. C. , Netto‐Ferreira J. C. , Becknell A. F. , Small R. D.
Published: December 2004

The photochemistry of an appropriately substituted bisimide has been studied in solution by conventional means and time resolved laser techniques as a model for the behavior of inherently photosensitive solvent soluble polyimides, whose photochemistry are not well understood. A mechanism for the photochemical insolubilization of the polymer systems is suggested based on the results for the model system, which is confirmed by time resolved laser studies of polyimide solutions. Phosphorescence quenching rate constants for the model compound indicate that the triplet excited state is about one order of magnitude more reactive than triplet benzophenone, an increase most likely due to the inductive effect of the imide moieties.
Basic functionalization of polyethylene in the melt
Authors: Simmons A. , Baker W. E.
Published: December 2004

The production of a polymer containing basic functional groups via the reactive processing of polyethylene was investigated. Grafting of dimethylamino ethyl methacrylate, DMAEMA, to linear low‐density polyethylene in the melt was carried out, and the effects of initiator type, feed composition, and reaction time and temperature were studied. The extent of grafting was determined by Fourier transform infrared and 1H nuclear magnetic resonance spectroscopy, and the degree of cross‐linking was observed by measuring the products' melt indices. Thermal stability of the product was investigated using differential scanning calorimetry. Materials containing up to 3 wt% of grafted DMAEMA were prepared. The choice of appropriate feed compositions and reaction conditions allows the production of a material containing the maximum amount of grafted DMAEMA, while minimizing cross‐linking. The grafted polyethylene produced under these conditions is more stable than the starting material, suggesting an antioxidant effect of the grafted moieties. The functional polymer produced should be of interest for the preparation of polymer blends with acidic polymers by virtue of the miscibility enhancement that could occur as compared with the hydrocarbon precursor.
On correlations of primary normal stresses in polymer solutions
Authors: Ait‐Kadi A. , Choplin L. , Carreau P. J.
Published: December 2004

Primary normal stress difference data of some 32 different polymer solutions have been examined and correlated to the shear stress by a simple power‐law model. The normal stress at constant shear stress is shown to increase with the molecular weight of the polymer, but decreases with the polymer concentration. The method proposed by Abdel‐Khalik, et al., for predicting the primary normal stress difference from viscosity data for these polymer solutions is inadequate. The FENE‐P dumbbell model is used to obtain master curves combining normal stress and viscosity data as a function of a dimensionless shear rate. It is found that this presents several drawbacks. It predicts shear‐thinning effects with a power‐law slope of −2/3, which is found to be too restrictive. The model fails to predict shear‐thinning effects for dimensionless shear rates λEγ lower than approximately 0.5. It also fails to predict satisfactorily the low shear rate value of the dimensionless combination of viscosity and first normal stress coefficient Ψ1/λE(η − ηs). An empirically modified correlation is proposed. The fit for a series of polyacrylamide (Dow Separan AP‐30) solutions is very good. In the case of a series of monodisperse polystyrene solutions, the fit is not as good, as the data show a more pronounced effect of polymer concentration at high shear rates.
An analysis of the extrusion welding process
Authors: Michel P.
Published: December 2004

A mathematical model has been developed for the heating phase of extrusion welding. It is shown that weld quality is mainly determined by melting a layer of the base material. All the parameters relevant to the heating phase are shown to affect weld quality through their effect on the thickness of the molten layer in the base material. It is shown that these parameters can be well controlled.
Computer‐aided optimization of the parameters of heated‐tool butt welding
Authors: Potente H. , Natrop J.
Published: December 2004

Welding represents one of the key stages in the manufacture of injection molded or blow molded plastics products. One process frequently employed is heated‐tool butt welding. However, the high seam quality associated with this process can only be attained through reliable process control and optimized welding parameters. This paper presents a simple new method for determining these parameters. Mathematical and physical descriptions of the individual process stages and a computer‐controlled heated‐tool butt welding machine serve as the basis for determining the parameters.
The impact strength of butt welded vibration welds related to microstructure and welding history
Authors: Schlarb Alois K. , Ehrenstein Gottfried W.
Published: December 2004

A study has been made of vibration butt welds between plaques of polypropylene. The quality of the welds, as determined by impact tests, has been examined as a function of the welding variables: pressure and vibration amplitude. In addition, the microstructure of the welds has also been examined, classified, and correlated with the welding variables and weld quality. Penetration as a function of time shows three distinct regimes and It is shown that the impact strength of the welds is independent of time once the third regime is reached. The time required to reach the third regime decreases as pressure or amplitude increases and is more sensitive to amplitude of vibration than to pressure. The highest quality welds were produced at low pressure and low amplitude with corresponding long times to reach regime three and exhibited a unique, readily identifiable microstructure.
On the modeling of continuous mixers. Part II: The cokneader
Authors: Elemans P. H. M. , Meijer H. E. H.
Published: December 2004

The Buss cokneader is a single‐screw extruder with interrupted flights. Pins from the barrel are inserted into the screw channel. The screw is both rotating and oscillating. Due to this action, screw flights are continuously wiped by the pins. During one passage of the pin, the material is not only subjected to high shear stress, but it is reoriented as well, thus promoting the distributive mixing process by the local weaving action of the pins and screw flights. Attempts to model the cokneader tend to focus on a single pin passing through the hole in a screw flight (1, 2). However, a more comprehensive model can start with the same equations that apply to the corotating twin‐screw extruder (3). Because the effect of leakage flows on the local pressure gradient has to be considered along with the effect of the local dragging action of the pins (neglecting the oscillatory action), experiments with model liquids have been performed to evaluate the comprehensive model. Additional experiments with a Plexiglas‐wailed cokneader support the calculations concerning filled lengths in various screw geometries. These results, and those of model calculations, which are extended to the nonisothermal, non‐Newtonian situation, are presented.
Modeling nonisothermal impregnation of fibrous media with reactive polymer resin
Authors: Chan Albert W. , Hwang Sun‐Tak
Published: December 2004

The manufacture of polymer composites through resin transfer molding (RTM) or structural reaction injection molding (SRIM) involves the impregnation of a fibrous reinforcement in a mold cavity with a reactive polymer resin. The design of RTM and SRIM operations requires an understanding of the various parameters, such as materials properties, mold geometry, and mold filling conditions, that affect the resin impregnation process. Modeling provides a potential tool for analyzing the relationships among the important parameters. The present work provides the physical model and finite element formulations for simulating the mold filling stage. Resin flow through the fibers is modeled using two‐dimensional Darcian flow. Simultaneous resin reaction and heat transfer among resin, mold walls, and fibers are considered in the model. The proposed technique emphasizes the use of the least squares finite element method to solve the convection dominated mass and energy equations for the resin. Excellent numerical stability of the proposed technique provides a powerful numerical method for the modeling of polymer processing systems characterized by convection dominated transport equations. Results from example numerical studies for SRIM of polyurethane/glass fiber composites were presented to illustrate the application of the proposed model and numerical scheme.
A rheological method for the study of crosslinking of ethylene acetate and ethylene acrylic ester copolymer in a polypropylene matrix
Authors: Cassagnau P. , Bert M. , Verney V. , Michel A.
Published: December 2004

Transesterification may be used to crosslink a copolymer such as ethylene vinyl acetate with poly(ethylene acrylate‐co‐propylene) in the presence of dibutyltin oxide as a catalyst. A rheological study of the mechanism of this exchange reaction has been made: The kinetics of the crosslinking reaction was determined by studying the time and temperature dependence of the dynamic storage modulus G′(t, T)ω. Kinetic curves obtained for different reactive blends (EVA, PP/EVA, and PPf/EVA) allowed for the evaluation of the activation energy of the reaction and, thus, specified the appropriate parameters (temperature and time) for carrying out this reaction in a molten state.
Flow field analysis of the kneading disc region in a co‐rotating twin screw extruder
Authors: Yang Haur‐Horng , Manas‐Zloczower Ica
Published: December 2004

Co‐rotating, intermeshing twin screw extruders are widely used in polymer compounding and blending. Among the different modules of the co‐rotating twin screw extruder, the kneading discs are the dominant ones in determining mixing efficiency. The major difficulty in solving the flow problem in the kneading disc region arises from the complex geometry and the time‐dependent flow boundaries as the discs rotate. In this work, a fluid dynamics analysis package—FIDAP—using the finite element method was employed to simulate the flow patterns in the kneading disc region of a Werner & Pfleiderer ZSK‐30 co‐rotating twin screw extruder. The problem of time dependent flow boundaries was solved by selecting a number of sequential geometries to represent a complete mixing cycle. The flow field was characterized in terms of velocity profiles, pressure distributions, shear stresses generated and a parameter λ quantifying the elongational flow components. The last two parameters are the most important ones in analyzing mixing efficiency. The influence of design variables (stagger angle, right or left handed configuration) and processing conditions (rpm, axial pressure gradient) on the flow characteristics was analyzed.
Compatibilization of a polystyrene‐polyethylene blend through reactive processing in a twin screw extruder
Authors: Teh J. W. , Rudin A.
Published: December 2004

Direct grafting of polystyrene onto polyethylene has been carried out in a twin screw extruder with an organic peroxide and a crosslinking co‐agent. The reaction extruded blends exhibited enhancement in impact properties at an optimum level of peroxide and co‐agent. Further improvement was achieved by introducing styrene monomer into the system during reactive extrusion. The structure and morphology of the blends were studied using differential scanning calorimetry, scanning electron microscopy, infrared spectroscopy, and size exclusion chromatography.
Liquid crystalline polymer/fluoropolymer blends: Preparation and properties of unidirectional “prepregs” and composite laminates
Authors: Dutta D. , Weiss R. A. , Kristal K.
Published: December 2004

Extruded films of liquid crystalline polymer (LCP)/fluoropolymer blends were melt drawn to develop uniaxial orientation of a microfibrillar dispersed LCP phase. The anisotropy of the films increased with increasing draw and LCP content in the blend. Laminated composite plates were prepared using the extruded sheets as prepreg. The mechanical properties and coefficient of thermal expansion (CTE) of the prepreg and laminates agreed well with predictions from composite lamination theories. The potential for replacing glass fiber reinforced fluoropolymers with LCP/fluoropolymer blends in applications such as microwave circuit boards is discussed.
Thermoplastic character of polyimide blends
Authors: Han B. J. , Park Jae M. , Gryte Carl C.
Published: December 2004

Polyimide blends consisting of pyromellitic dianhydride/4,4′‐oxydianiline (PMDA/ODA) and biphenyl‐tetracarboxylic dianhydride/p‐phenylene diamine (BPDA/PDA) show a distinct glass transition behavior at temperatures lower than each component does. Disruption of molecular packing by blending of polymers having dissimilar interaction sites leads to a significant increase in molecular mobility at much lower temperatures. This is examined by laminating two pieces of film cast from the blend and measuring the adhesive strength at the interface. A strong adhesion, 11.5 N/cm (6.6 lbf/in) by 180° peel test, was achieved indicating interpenetration of polyimide molecules. It was also found that the polyimide blends can be converted into highly ordered states by mechanical deformation of the blends above their glass transition temperatures (Tgs).
The microwave processability of semicrystalline polymers
Authors: Chen M. , Hellgeth J. W. , Siochi E. J. , Ward T. C. , McGrath J. E.
Published: December 2004

The overall objective of these studies was to investigate the relationship between polymer structure and microwave absorptivity. In this paper, the microwave processing of semicrystalline polymers such as poly(ether ether ketone) (PEEK), nylons, and poly(ethylene terephthalate) (PET), via a cylindrical resonance wave cavity and a rectangular standing wave applicator is described. These polymeric materials were irradiated in low power (< 50W) electric fields at 2.45 GHz. Silicone flexible molds were necessary for improved processing of nylons and PEEK at temperatures below their Tc Rapid heating rates were observed between the glass transition temperature, Tg, and the melting temperature, Tm, for all these polymers provided that Tc was exceeded. Both dynamic mechanical thermal analysis (DMTA) and dielectric thermal analysis (DETA) spectra were utilized to predict the heating phenomena between amorphous and semicrystalline materials and to explain the rapid crystallizing rate of PEEK. above its glass transition temperature. Correlations were drawn between (a) the apparent activation energy and the critical temperature (Tc) and (b) the shape of the dielectric spectra at 2.45 GHz and its shape in kHz region.
Interaction of nonhomogeneous shear, nonlinear viscoelasticity, and yield of a solid polymer
Authors: Wineman A. S. , Waldron Jr. W. K.
Published: December 2004

A constitutive equation for small strain viscoelastic response is considered in which stress relaxation. occurs faster as strain increases. The constitutive equation is of single integral type and has a psuedo‐ or material time function which is calculated from a strain dependent shift function. First, it is shown that such a constitutive equation can account for yield as observed in polymers for a number of different stress and strain histories. Next, the constitutive equation is used in the analysis of the problem in which a hollow cylinder is fixed at its inner surface and a moment history is applied to its outer surface. This causes the cylindrical surfaces to rotate about the central axis, thereby inducing a radial shear strain distribution. It is shown that there is a time when the material near the inner support begins to yield and a layer of large shear strain gradient begins to grow rapidly. It is also shown that the stress or strain history at a material element will generally not be one of the standard histories used to study yield.
Review of stabilization of polyolefin insulated conductors. Part I: Theory and factors affecting stability
Authors: Hendrickson L. , Connole Kent B.
Published: December 2004

The understanding of the failure mechanism causing cracks in insulated telephone wire is critical to developing a solution to the problem. This paper reviews the antioxidant and metal deactivator theory as it applies to polyolefins and reviews the factors, both internal to the polymer and external which affect stability. Degradation theory in vacuum and air is reviewed. Primary and secondary antioxidants are discussed as are multifunctional metal deactivator/antioxidant molecules. The internal factors affecting thermal stability which are discussed include: polymer synthesis process, molecular weight, molecular weight distribution, crystallinity, phase state, orientation, amount of antioxidant, amount of metal deactivator, and amount of blowing agent. The external factors affecting long term life are: temperature, oxygen, ozone, stress, filling compound, and presence of copper.
Numerical simulation of fiber orientation in injection molding of short‐fiber‐reinforced thermoplastics
Authors: Chung S. T. , Kwon T. H.
Published: December 2004

The present study develops a numerical simulation program to predict the transient behavior of fiber orientations together with a mold filling simulation for short‐fiber‐reinforced thermoplastics in arbitrary three‐dimensional injection mold cavities. The Dinh‐Armstrong model including an additional stress due to the existence of fibers is incorporated into the Hele‐Shaw equation to result in a new pressure equation governing the filling process. The mold filling simulation is performed by solving the new pressure equation and energy equation via a finite element/finite difference method as well as evolution equations for the second‐order orientation tensor via the fourth‐order Runge‐Kutta method. The fiber orientation tensor is determined at every layer of each element across the thickness of molded parts with appropriate tensor transformations for arbitrary three‐dimensional cavity space.
Steady‐State and dynamic properties of concentrated fiber‐filled thermoplastics
Authors: Greene Joseph P. , Wilkes James O.
Published: December 2004

Rheometric data for short‐fiber‐filled thermoplastics are presented using a parallel‐plate viscometer. Polypropylene tensile bars contain short and long fibers with glass weight percentages of 0%, 5%, 10%, 20%, and 30%, polycarbonate tensile bars with glass percentages of 0%, 5%, and 10% long fibers, and nylon 6/6 tensile bars with 0%, 15%, 30%, and 45% short fibers. The short fibers were initially 3 mm in length and 12.7 microns in diameter. The long fibers were initially 6 mm in length and 10 microns in diameter. In the steady‐state experiments, the fibers increase the viscous stresses and the normal stresses in proportion to the concentration of fibers. At low shear rates, the viscosity is increased by the addition of the fibers, but at high shear rates the viscosity approaches that of the neat resin. In dynamic testing, the fibers increase the viscous and elastic components as measured by the complex viscosity and modulus. The fibers increase the viscous and elastic nature of the fiber‐filled composite at low frequencies and to a lesser extent at higher frequencies. The fibers increase the elastic component more than the viscous component at low frequencies and less at higher frequencies as demonstrated by tan δ.
Particle Size Distribution and Aspect Ratio of Organic Pigments
Authors: Grubenmann Arnold
Published: December 2004

Particle size and aspect ratio are amongst the most important parameters which determine the application properties of pigments, fillers and powders for ceramics. A statistical characterization of the samples is therefore needed. In this paper we discuss the measurement of bivariate size distributions of organic pigments and describe a correction procedure for particles with interchanged crystallographic axes. During the crystallization of a pigment, the larger aspect ratios usually result from faster growth rates.
A Rapid Method for Determination of Changes in Shape of Comminuted Particles Using a Laser Diffractometer
Authors: Austin Leonard G. , Trass Olev , Dumm Timothy F. , Koka Venkat R.
Published: December 2004

The size distributions of carefully screened √2 size fractions of ground materials were determined using a Microtrac laser diffractometer. The size distributions were fitted to the empirical function P(x) = 1/[1 + (x50/x)λ] where P(x) is cumulative mass fraction less than Microtrac size, x. The standard deviation of λ for a 50 second test time was approximately 0.5, so that seventeen test times give a mean with an estimated error within ± 0.25 (95% confidence level). Values of λ were 5.44, 4.82, 4.40 for a coal ground under different conditions, indicating statistically different shape distributions; the average value for mica was 2.91 owing to the high aspect ratio of the particles. The ratio of x50 to the geometric mean sieve size was 1.2 for the coal and 0.70 for mica.
Über Ferroferrocyanide
Authors: Müller Erich , Treadwell W.
Published: January 2005

Es gibt höchstwahrscheinlich nur folgende Ferroferrocyanide: K2FeoFeoc3, K4Feo4Feoc3, Feo2Feoc, deren Löslichkeit in dieser Reihenfolge steigt.
Zur Geschichte des Zeiseschen Merkaptans und seines Namens (1833)
Authors: Diergart Paul
Published: January 2005

Da die Erklärungen des Namens Merkaptan oft ungenau sind, wird in eine Untersuchung eingetreten. Zuvor wird begründet, warum der deutschen Schreibweise Merkaptan mit k heute der Vorzug zu geben ist, aber Mercaptum mit c. Die Zeitschriften zur Zeit der Entdeckung (1833) bringen verschiedenartige Ableitungen des Wortes Mercaptum, die sprachlich und chemisch dennoch zu rechtfertigen sind. Der aus der dänischen Urschrift beigebrachte Wille des Entdeckers und Namengebers Zeise ist maßgebend: mercaptum von mercurio aptum, merkaptan von mercurium captans. Nach näherer Begründung des Jahres 1833 als Entdeckungsjahr werden die Ansichten von Berzelius, Liebig und Wöhler über die Zeisesche Arbeit geschildert. Experimentell ist diese allen dreien vorzüglich, ja meisterhaft, aber beim Lesen der Abhandlung selbst ist ihnen mit Recht, „wie wenn man auf Schlitten durch Sand fährt”︁. Es wird dann ausgeführt, daß der Entdecker vor Liebig und Berzelius die Analogie zwischen Merkaptan und Alkohol ausgesprochen hat, und kurze Bemerkungen aus Zeises sonstigem Wirken bilden den Schluß. Alle notwendigen Belege sind angegeben.
Quantitative elektrolytische Reduktionen. II. Teil: Reduktion der Salpetersäure
Authors: Nietz Edgar
Published: January 2005

Bei der quantitativen Reduktion von Nitrat‐Ion zu Ammonium‐Ion an schwammig verkupferter Kathode kommen folgende Fehlerquellen in Betracht:

ein Teil des Stickstoffes entweicht als Gas. Die Maßnahmen zur Verringerung dieses Fehlers waren erfolglos.

Während des Spülens der Cu‐Kathode löst sich unter Verbrauch von Schwefelsäure etwas Kupfer auf. Durch Neutralisieren der reduzierten Lösung vor Unterbrechung des Stroms konnte dieser Fehler praktisch ausgeschaltet werden.
Die Amphoterie des Blei(2)‐ und des Blei(4) oxyds
Authors: Töpelmann Herbert
Published: January 2005

Der allgemein‐chemische Charakter und die Amphoterie von Blei(2)‐ und Blei(4)oxyd werden in Zusammenhang mit den derzeitigen Kenntnissen vom Bau der Blei(2)‐ und Blei(4)‐ atomionen erörtert.
Über die Konstitution des Santenons und der Santensäure. Mit 3 Figuren
Authors: Enkvist Terje
Published: January 2005

1. Bei einem Versuch zur Totalsynthese der Santensäure wurde nicht diese Säure, sondern eine mit derselben isomere, neue, anhydridbildende Säure, die Cis‐Allosantensäure erhalten, deren Struktur durch die Totalsynthese festgestellt ist, und die der gewöhnlich angegebenen ebenen Formel der Santensäure entspricht.
Die Einwirkung von Chlor auf Titandioxyd
Authors: Pamfilov A. V. , Chudjakov A. S. , Standel E. G.
Published: January 2005

1. Es wurde ein Zusammenhang zwischen Temperatur und Verlauf des Chlorierungsprozesses des Titandioxyds festgestellt.
Über die potentiometrische Bestimmung der Unterphosphorsäure in Gegenwart von Phosphorsäure und phosphoriger Säure
Authors: Grundmann Werner , Hellmich Ruth
Published: January 2005

Die indirekte Titration der Unterphosphorsäure mit Silbernitrat und Ammoniumrhodanid liefert keine brauchbaren Werte.
Über den Austausch eines Halogenatoms des aromatischen Kerns gegen die Nitrilgruppe unter dem Einfluß von Nickelcyanür
Authors: Ślebodzíński T.
Published: January 2005

Es wurde die Austauschreaktion eines Halogens des aromatischen Kerns gegen die Nitrilgruppe, in Gegenwart von Nickelcyanür, untersucht. Die Reaktion wurde mit Chlor‐, Brom‐ und Jodbenzol, o‐, m‐ und p‐Chlor‐ und Jodtoluol, mit o ‐ und m‐Bromtoluol, p‐Dichlorbenzol, mit m‐ Jodbenzoesaure, p‐Nitrobrombenzol, p‐Bromanilin, α‐Bromnaphthalin und p, p′‐Dibromdiphenyl ausgeführt.
Zur Kenntnis der Oxydation von Carbeniumsalzen mit Wasserstoffsuperoxyd. [Pyrenium, XXXI]
Authors: Dilthey W. , Quint Ferd. , Dierichs H.
Published: January 2005

Die Methode der Oxydation von Pyreniumsalzen kann auf einfache Carbeniumsalze übertragen werden. Mit ihr kann die relative Haftfestigkeit aromatischer Kerne am zentralen C‐Atom ermittelt werden.
Über die Einwirkung von Sulfitkochsäuren auf Zuckerarten und die Vergärbarkeit von Sulfitablaugen verschiedener Herkunft
Authors: Hägglund E. , Heiwinkel H. , Bergek T.
Published: January 2005

Bei dem Sulfitaufschluß des Holzes wird ein Teil des gelösten Zuckers — vermutlich über die Zuckerbisulfitverbindung und eine labile Ketosulfonsäure — in Aldonsäuren verwandelt. Aus Ablaugen von Kochungen mit stark sauren Bisulfitlösungen lassen sich Zuckersulfonsäuren in geringen Mengen gewinnen. Mit weniger sauren Bisulfitlösungen entstehen Zuckersulfonsäuren, die mit den vorhergenannten nicht identisch sind. Diese Sulfonsäuren sind beständig in kochenden, verdünnten Mineralsäuren und kaltem, verdünntem Alkali.
Über das Schicksal des Vitamins B1 der Gerste in der Graupenmühle. Mit 1 Abbildung
Authors: Fink Hermann , Just Felix
Published: January 2005

Der Vitamin B1‐Gehalt von 7 Graupentypen beträgt 100 bis 115 γ pro 100 g Trockensubstanz bzw. 85–98 γ pro 100 g mit 15% Wassergehalt bei den Körnungen 0, 1, 2, 2/0, 3/0, 4/0 und 155 bzw. 132 γ bei 5/0. Bei Gerstenflocken, Gerstengrieß und Gerstengrütze beträgt er 54 bzw. 46 γ, 295 bzw. 251 γ und 171 bzw. 145 γ.
Über die Raumverhältnisse im System Cellulose‐Wasser und über die Packungsdichte der Cellulosefasern
Authors: Hermans P. H. , Vermaas D. , Hermans J. J.
Published: January 2005

Bei der theoretischen Deutung von Dichtemessungen an Cellulose‐präparaten und ähnlichen quellenden Systemen hat man bisher übersehen, daß der Dichtebegriff im üblichen Sinne ein typisch makroskopischer ist. Bei seiner kritiklosen Extrapolation auf Systeme deren Dispersion zum Teil bis in molekularen Dimension hinein reicht, gelangt man dann leicht zu unklaren oder gar falschen Vorstellungen. Die Raumerfüllungsverhältnisse in solchen Systemen sind eher ähnlich den in Packungen von Kugeln und von festen Teilchen verschiedener Größe und Form vorliegenden zu behandeln.
Die Einwirkung von Bromcyan auf Imidazol und 4(5)‐Methylimidazol
Authors: Giesemann Heinz
Published: January 2005

Durch Umsetzung von Imidazol und 4(5)‐Methylimidazol mit Bromcyan in absoluten Lösungsmitteln entstehen nach dem v. Braunschen Reaktionsmechanismus die 1‐Cyanderivate der Imidazole neben gleichen Teilen der entsprechenden Hydrobromide. Die 1‐Cyanderivate sind wenig beständige Verbindungen.
Über β‐Mercaptozimtsäureester und seine Derivate
Authors: Scheibler Helmuth , Frenz Bruno
Published: January 2005

Der nach verschiedenen Verfahren dargestellte β‐Mercaptozimtsäureäthylester wurde eingehend untersucht. So wurde die Gleichgewichtslage Thioenol/Thioketon bestimmt, die Oxydation des Thioenols zum Disulfid und die Umsetzungen des Natrium‐β‐mercaptozimtsäureäthylesters mit Alkyl‐ und Acylhalogeniden durchgeführt. Ferner wurde versucht, die Farberscheinungen, die nicht nur bei der Thioketoform, sondern auch bei den aus β‐Mercaptozimtsäureäthylester erhaltenen Thioäthern auftreten, zu deuten.
Substituierte Benzyulphenylsulfone und Benzylsulfonamide und deren Cyanäthylierungsprodukte als Insekticide
Authors: Misra G. S. , Asthana R. S.
Published: January 2005

Es wird über die insekticide Wirkung von cyanäthylierten substituierten Benzylphenylsulfonen und Benzylsulfonamiden im Vergleich mit bekannten Insekticiden berichtet. Die untersuchten Präparate zeigen eine erstaunlich gute Wirksamkeit. Der experimentelle Teil bringt eine genaue Beschreibung der Darstellung der Darstellung der Testsubstanzen.
Über die Bildungsweise der 2‐Oxynaphthoesäure‐(3)
Authors: Lecher Hans Z. , Scalera Mario
Published: January 2005

Eine Veröffentlichung von SEIDEL, WOLF und KRAUSE(1) wird ergänzt: 1. durch Hinweis auf frühere Veröffentlichungen, 2. durch Beschreibung von Bereitung und Eigenschaften wasserfreier Dioxanlösungen von Natrium‐β‐naphtholat.

Ein Verfahren zur Herstellung von 2‐Oxynaphthoesäure‐(3) in einer solchen Lösung wird diskutiert und beschrieben.

Die Bildung dieser Säure in einer Lösung von Natrium‐β‐naphtholat in β‐Naphthol wird beschrieben.
1,3,4,5,6‐Pentachlorcyclohexen‐(1) vom Schmp. 36,5–36,8°C
Authors: Fricke G.
Published: January 2005

Das bisher nur als viskose Flüssigkeit bekannte Pentachlorcyclohexen vom Sdp.6–7 125° wurde kristallisiert erhalten. Der Schmp. beträgt 36,5–36,8°C.
Über die Kondensation von 4‐Vinylpyridin und 2‐Methyl‐6‐vinylpyridin mit primären und sekundären Aminen
Authors: Profft Elmar
Published: January 2005

Es wird das Verhalten des 4‐Vinylpyridins und 2‐Methyl‐6‐vinylpyridins gegenüber aliphatischen, aromatischen und heterocyclischen Aminen, sowie Hexamethylendiamin, untersucht, und zwar sowohl gegenüber sekundären als auch primären Aminen.

Beide Vinylpyridine erwiesen sich als besonders reaktionsfreudig. 4‐Vinylpyridin zeigte in einer Anzahl der untersuchten Fälle besondere Neigung zur Polymerisation, so daß es nicht zu einer Anlagerungsreaktion kam.
Untersuchungen über Stilbene. VIII. Notiz über die Darstellung von Stilbenhydantoinderivaten
Authors: Drefahl Günther , Hackbarth Werner
Published: January 2005

Durch Umsetzung von Stilbencarbonylverbindungen mit Natriumcyanid und Ammoniumbikarbonat wurden in 5‐Stellung durch den Stilbenrest substituierte Hydantoine dargestellt.
Versuche zur Bestimmung und Charakterisierung biologisch wichtiger Pyrrole
Authors: Müller Gerhard
Published: January 2005

Es wurden Nachweisreaktionen für Pyrrole erprobt, die es ermöglichen, diese Körper auch in biologischem Material zu finden und zu trennen. Dabei erwiesen sich Isatin‐ und HgCl2‐Verbindungen der Pyrrole als geeignet. Außerdem wurden Spektren der farbigen Kondensationsprodukte der Pyrrole und HgCl2‐Verbindungen mit p‐Dimethyl‐aminozimtaldehyd ausgemessen, sowie die Pyrrole und deren Isatinverbindungen papierchromatographisch untersucht.
Partialsynthese der Δ5‐3α‐Oxycholensäure und der Δ6‐3α‐Oxycholensäure
Authors: Schubert A. , Damker Chr.
Published: January 2005

Die partielle Abspaltung eines Mols Wasser bei in 3‐α Stellung substituierter 6 β‐Oxycholansäure‐ und Allocholansäurederivaten führt im 1. Fall zur Darstellung der Δ6 ‐ 3 α‐Oxycholensäure und im 2. Fall zur Darstellung der Δ5 ‐ 3 α‐Oxycholensäure als Grundkörper. Von beiden Säuren wird die Herstellung einiger Derivate beschrieben. Zur Charakterisierung der Δ6‐Sterinverbindungen der Normalreihe und zur Unterscheidung gegenüber den Isomeren Δ5‐Verbindungen werden die bei 1650 cm−1 und bei 745 cm−1 auftretenden Banden der Δ6‐Doppelbindung zugeordnet.
Substituted Sulphones and Sulphonamides and their cyanoethylation products as insecticides
Authors: Misra G. S. , Asthana R. S.
Published: January 2005

The insecticidal activity of some substituted sulphones and sulphonamides and their cyanoethylation products is discussed in relation to the already well‐known insecticides. Some of the compounds prepared showed excellent activity. In the experimental part, the preparation of the substances thus tested has been described.
Über die Katalytische Wirksamkeit poröser Kontakte am Beispiel der Luftoxydation von o‐Xylol
Authors: Leibnitz E. , Könnecke H.‐G. , Knopel H.
Published: January 2005

Es wird über Oxydationsversuche von o‐Xylol zu Phthalsäure in der Gasphase an Vanadinoxydkontakten berichtet. Durch Texturbestimmung der Kontakte wird auf die Bedeutung der Makroporenstruktur der Kontakte im Hinblick auf die katalytische Wirksamkeit hingewiesen. Durch Variation der Versuchsparameter werden zur Erzielung maximaler Phthalsäureausbeuten 550° C und 7facher theoretischer Sauerstoffüberschuß gefunden, wobei die beste Aktivität bei Kontakten mit mindest 40 μ Porenradius erreicht wird.
Zur Chemie der kondensierten Phosphate und Arsenate. XVII. Der Verlauf und die Produkte der Entwässerung der Monophosphorsäure H3PO4
Authors: Thilo Erich , Sauer Rudolf
Published: January 2005

Bei der thermischen Entwässerung der Monophosphorsäure bilden sich Gemische von Polyphosphorsäuren mit linearen Kettenanionen, solange der P2O5‐Gehalt ≤ ∼ 85% bleibt. Bei höheren P2O5‐Gehalten treten auch vernetzte Phosphorsäuren auf. Die Zusammensetzung der Entwässerungsprodukte entspricht Gleichgewichten zwischen den verschiedenen Polyphosphorsäuren.

Auch auf andere Weise hergestellte P2O5–H2O‐Schmelzen haben bei gleichem P2O5‐Gehalt dieselbe Zusammensetzung. Alle Schmelzen, auch die P2O5‐reichsten, enthalten noch H3PO4 und diejenigen, deren P2O5‐Gehalt nicht gt; 83% ist, nicht konstitutionell gebundenes Wasser. Aus reiner H3PO4 läßt sich auf thermischem Wege keine reine Polyphosphorsäure einheitlichen Kondensationsgrades herstellen.

Die Zusammensetzungen der einzelnen Schmelzen ergeben sich aus der quantitativen chromatographischen Analyse. Kurz eingegangen wird auf die Bildung wasserhaltiger Kalium‐Polyphosphate, die Umwandlung K‐Polyphosphat ⇄ Na‐Polyphosphat und einen Vergleich zwischen dem Verlauf der Entwässerung der H3PO4 = H[H2PO4] und Li[H2PO4], der bei beiden Substanzen praktisch gleich ist.
Untersuchungen an Magnetogrammträgern. V. Über die Reduktion von Eisen(III)‐hydroxyden mit Amino‐imino‐methansulfinsäure
Authors: Ackermann Gerhard
Published: January 2005

Es wird über Versuche zur Darstellung von Magnetiten durch Reduktion von Eisen(III)‐hydroxyden mittels Amino‐imino‐methansulfinsäure berichtet. Das wirksame Agens ist die Sulfoxylsäure, die beim Zerfall der Sulfinsäure in alkalischer Lösung ensteht. Durch elektronenmikroskopische Untersuchungen wird bewiesen, daß die Magnetitbildung über die Lösung geht, da unabhängig von der Art der Ausgangshydroxyde stets Magnetit‐Kuben gefunden werden.
Dicarbonsäuren in Paraffin‐Oxydations‐Produkten
Authors: Reinheckel H.
Published: January 2005

Die Paraffin‐Oxydationsprodukte des VEB Hydrierwerk Rodleben wurden auf ihren Gehalt an Dicarbonsäuren untersucht. Im folgenden wird beschrieben, welche und wieviel Dicarbonsäuren isoliert werden konnten und welche Methode der Aufarbeitung angewandt wurde. Die Anwendbarkeit für Polykondensationen wurde geprüft.