bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of mild steel corrosion in 1N sulphuric acid through indole
Authors: Moretti G. , Quartarone G. , Tassan A. , Zingales A.
Published: December 2004

The corrosion inhibition of mild steel in 1N sulphuric acid containing various concentrations of indole was studied in the temperature range of 25–70°C through the use of potentiodynamic polarization curves. The indole was found to shift the corrosion potentials to positive values and to decrease the dissolution of mild steel and hydrogen evolution reaction. The effect, however, was more pronounced on the anodic rather then the cathodic process. Indole did not generally affect the corrosion reaction mechanism (blocking effect). The reported activation energy (Ea) values indicate that the inhibiting effect increased with the indole concentration. At temperatures of 25, 40, 55 and 70°C the adsorption behaviour of the indole follows Temkin's isotherm with a standard free energy of adsorption of −54.49, −39.41, −43.49 and −55.25 kJ/mol, respectively.
Die Bedeutung der pH‐abhängigen Durchbruchsreaktionen bei NiCrMo‐Werkstoffen in Medien der Chemie‐ und Umwelttechnik mit hohem Redoxpotential
Authors: Voigt C. , Werner H. , Kirchheiner R. , Schambach L.
Published: December 2004

Gegenüber CrNiMo‐Stählen zeigen NiCrMo‐Basislegierungen eine Besonderheit bei relativ positiven Potentialen. Infolge einer Durchbruchsreaktion, die nicht an die Gegenwart von Cl− gebunden ist, lösen sich im pH‐Bereich 4–9 die Ni‐Legierungen stabil und gleichmäßig auf, wohingegen die Stähle keinen Angriff zeigen. Untersucht wurde das Phänomen an den Stählen 1.4563 (Nicrofer 3127 LC) und 1.4562 (Nicrofer 3127 hMo) sowie Ni‐Legierungen 2.4856 (Nicrofer 6020 hMo) und 2.4605 (Nicrofer 5923 hMo) in Cl−‐ und SO2−4‐Lösungen im pH‐Bereich von 3–10. In der Durchbruchsreaktion lösen sich Cr und Mo 6wertig, Ni 2wertig auf. Das Durchbruchspotential ist in Cl−‐ und SO‐Lösungen gleich und wird kaum vom Mo‐Gehalt beeinflußt. Die Reaktionsgeschwindigkeit nimmt mit steigendem Mo‐Gehalt der Legierung zu.

Diese Werkstoffeigenschaft der Ni‐Legierungen muß beachtet werden, wenn sie in praktischen, schwach sauren his schwach alkalischen Medien, die ein hohes Redoxpotential besitzen, eingesetzt werden sollen.
The effect of niobium on the oxidation behaviour of fully Austenitic Fe‐15% Cr‐15%Ni stainless steels
Authors: Ramanathan L. V. , Pohl M. , Padilha A. F.
Published: December 2004

The influence of niobium content (0.5–2.0 wt.%) on the oxidation behaviour of Fe‐15% Cr‐15% Ni austenitic stainless steels has been studied by cyclic oxidation tests in air at different temperatures in the range 800–1200°C. The isothermal oxidation rate, the scaling index and the cumulative oxide loss decreased with increasing niobium content. X‐ray diffraction and fluorescence analysis of detached oxide scales revealed that the niobium in the alloy matrix facilitated the formation of chromium rich (Fe, Cr)2O3 and niobium containing mixed oxide near the metal/metal oxide boundary, which decreased further oxidation. SEM/EDX investigations revealed that the external oxide changed from being predominantly iron rich iron‐chromium oxide to being chromium rich iron‐chromium oxide.
Qualitätsmanagement und Akkreditierung von Prüflaboratorien
Authors: Golze M.
Published: December 2004

Der Beitrag behandelt das Qualitätsmanagement (QM) in Prüflaboratorien. Der Schwerpunkt liegt einerseits bei den technischen Aspekten wie der Kalibrierung, der internen und externen Qualitätskontrolle und der Validierung und andererseits bei einigen Gesichtspunkten des Labormanagements, z.B. der Qualitätsdokumentation, dem Management‐Review und den Qualitätsaudits. Die Notwendigkeit zur Laborakkreditierung im gesetzlich geregelten Bereich und die Vorteile im gesetzlich nicht geregelten Bereich werden betont. Nach einer Erläuterung der Unterschiede zwischen Prüflaborakkreditierung und der Zertifizierung von QM‐Systemen werden einige neuere Entwicklungen auf dem Gebiet der Akkreditierung und des QM erwähnt.
Corrosion rate monitoring with computerized systems
Authors: Rocchini G.
Published: December 2004

Some observations concerning the aims of corrosion rate monitoring, the choice of the electrochemical parameter, the opportunity of optimising the measurement technique and the usefulness of developing specific software for computerised systems are made. The basic concepts for the evaluation of the mass loss of metals or alloys are introduced and some mathematical formulas of the method of successive approximations are given.

A short description of the SOFTCOR‐DC‐PHTS code is given, Which concerns its improvements and the most important points and stresses the significant differences between this program and commercial software and the potentialities of the present method.

The experimental applications, concerning the behaviours of Armco iron and SA 182 grades F11 and F22 carbon steels in inhibited 5% by weight HCl solutions at 75°C and SA 106 grade B carbon steel in solutions containing 100 gl−1 of EDTA at 100°C and different pH values, have demonstrated the existence of a discrepancy between direct and electrochemical determinations of the corrosion rate. The value of the electrochemical determination of the corrosion rate, obtained through potentiostatic measurements with a polarization time of 1 s, was higher than the mean value of the direct evaluation from weight loss data. The present results show that the electrochemical technique cannot reproduce the true behaviour of a corrosion process. However, the SOFTCOR‐DC‐PHTS program is very useful to deal with the problem of monitoring the corrosion rate of metals in acid media and to process experimental data without the intervention of an operator.

Finally, it has been experimentally demonstrated that the determination of the polarization resistance depends on the technique adopted for performing polarization measurements.
Beschichtungssysteme für Verbindungselemente in Kontakt mit Leichtmetallen
Authors: Reinhold B. , Strobl Ch.
Published: December 2004

Kontaktkorrosion an Leichtmetallegierungen kann nur dann vermieden werden, wenn entsprechende Stahl‐Anbauteile einen elektrochemisch kompatiblen Schutz erhalten oder durch elektrisch isolierende Barriereschichten der Korrosionsstromkreis unterbrochen wird. Stromdichte‐Potential‐Kurven an chromatierten Zink‐Legierungsüberzugen führten zu dem Ergebnis, daß durch Zink‐Nickelüberzüge eine weitgehende elektrochemische Anpassung an das Ruhepotential warmaushartbarer Aluminiumlegierungen der Gattung AlMgSi möglich ist. Demgegenüber liegen die Ruhepotentiale chromatierter Systeme auf Basis ZnFe bzw. ZnCo bei zu negativen Werten, um Kontaktkorrosion am Aluminium zu vermeiden. In praxisrelevanten Korrosionstests an Verbindungselementen bestätigte sich dieses Ergebnis; außerdem erwiesen sich zink‐ und aluminiumhaltige Sintersysteme, die galvanische Verzinnung sowie ternäre Kompositbeschichtungen auf Basis ZnSnAl als kompatibel mit Legierungen der Gattung AlMgSi.

Für Beschichtungselemente in Kontakt mit Magnesium ist mit isolierend wirksamen top coats ein befriedigender Kontaktkorrosionsschutz zu erzielen. Die Ergebnisse mit entsprechenden Duplexsystemen werden vorgestellt und Empfehlungen für Anwendungen in der Praxis abgeleitet.
Mikrostruktureinfluß auf das Rißfortschrittsverhalten bei nichteinstufigen Schwingbelastungen
Authors: Schulte K. , Nowack H. , Lütjering G.
Published: December 2004

Im Zusammenhang mit dem Rißfortschritt bei unregelmäßigen Belastungen treten signifikante Reihenfolgeneinflüsse auf. Bisher ist noch nicht hinreichend bekannt, inwieweit die Reihenfolgeneinflüsse durch die Mikrostruktur des Werkstoff und die sich daraus ergebenden mikrostrukturellen Rißfortschrittsmechanismen beeinflußt werden.

Es erfolgt die Darstellung der Ergebnisse von Untersuchungen, bei denen die Mikrostruktur durch die Wahl verschiedener Aluminiumlegierungen mit unterschiedlichen Wärmebehandlungen variiert wurde. Darüber hinaus wurde auch das Umgebungsmedium verändert, und zwar erfolgten Versuche im Vakuum, in Laborluft und in einer 3,5%igen Kochsalzlösung. Es wird versucht, das Verhalten auf der Grundlage kontinuumsmechanischer Betrachtungen sowie der Mikrostruktur der Aluminiumlegierungen zu erklären. Die Hinweise, die sich aus den mikrostrukturellen Untersuchungen und kontinuumsmechanischen Betrachtungen bezüglich der Reihenfolgeneinflüsse auf den Rißfortschritt ergeben, werden im einzelnen diskutiert.
Hartbearbeitung keramischer Werkstoffe, insbesondere mittels Ultraschall‐Erosion
Authors: Grathwohl G. , Iwanek H. , Thümmler F.
Published: December 2004

Verschiedene Hartbearbeitungsverfahren, darunter vor allem Ultraschallerosion (USM) und Funkenerosion (EDM) wurden eingesetzt, um das Bearbeitungsverhalten verschiedener Konstruktionskeramiken zu untersuchen. Die Anwendung von EDM ist auf Werkstoffe mit einem spezifischen elektrischen Widerstand under etwa 100 Ω cm beschränkt. Die Ultraschallbearbeitung kann dagegen für alle Keramiken, wenn auch mit sehr unterschiedlichen Ergebnissen eingesetzt werden. Es ergeben sich charakteristische Zusammenhänge zwischen der Rißzähigkeit der zu bearbeitenden Werkstoffe und dem USM‐Bearbeitungsergebnis; mit steigender Rißzähigkeit nimmt die erreichbare Bearbeitungsgeschwindigkeit stark ab, was mit einer Verringerung der Oberflächenrauhigkeit einhergeht. Der Werkzeugverschleiß wird dabei deutlich gesteigert. Die Einflüsse weiterer USM‐Parameter wie USM‐Amplitude und Partikelgröße des verwendeten Borkarbidpulvers werden diskutiert. In vergleichenden Festigkeitstests unterschiedlich endbearbeiteter Biegeproben stellt sich kein grundsätzlicher Nachteil der USM‐Methode heraus.
Production of stainless steel filters by liquid phase activated Gravity sintering
Authors: Danninger H. , Jangg G. , Giahi M.
Published: December 2004

Production of stainless steel filters by sintering the loose powders offers difficulties due to the stable oxide layers covering the particles and preventing formation of sintering necks. Boron compounds, i.e. NiB and BN, were found to activate sintering by both reducing the oxide layers and forming a liquid phase. The resulting samples offer excellent mechanical properties, in particular high ductility, as well as satisfactory permeability, while the corrosion resistance is not lower than with boron‐free stainless steels.
Spezialgläser und glaskeramische Materialien für neue Produktanwendungen
Authors: Petzoldt J.
Published: December 2004

Der Markt für den Werkstoff Glas in der westlichen Welt wird beschrieben und interessante Anwendungsgebiete werden genannt. Besonders handelt es sich hierbei um die Optronic, die Bio‐, Medizin‐ und Chemie‐Technik als spezielle Anwendungsgebiete für Produkte, fü4 die Spezialgläser oder glaskeramische Werkstoffe eine wesentliche Rolle spielen.

Aus diesen Anwendungsbeispielen werden Anforderungen für neue glasige und glaskeramische Materialien abgeleitet. Über Neuentwicklungen auf dem Gebiet der Optischen Gläser wird berichtet sowie eine vergleichende Darstellung mit polymeren Werkstoffen mit besonderen optischen Eigenschaften gegeben.

Als Besonders eindrucksvolles Beispiel für neue Anwendungen des Werkstoffes Glas bzw. Glaskeramik wird der Einsatz von Spezialgläsern in einem Laserfusionsexperiment beschrieben. Weiter wird die Herstellung und der Einsatz von 0‐Ausdehnungsglaskeramiken für spezielle Trenntechniken in der Biotechnologie und in der Medizintechnik eingesetzt werden können, beschreibt die Darstellung der Ergebnisse jüngster Entwicklungsarbeiten.
Eine effiziente Methode zur Ermittlung des Schädigungsbereiches bei Wöhleruntersuchungen
Authors: Weber H. , Dengel D.
Published: December 2004

Die Schadenslinie nach French läßt sich bei statistischer Planung und Auswertung der zur Ermittlung der Schadenslinie benötigten Versuche in einen quantitativ beschreibbaren „Schädigungsbereich”︁ überführen. Das dazu erforderliche Versuchsaufkommen ist jedoch beachtlich (etwa 400 Proben).

Die erneute Auswertung einer vorliegenden Großzahluntersuchung vonPanagopoulos[23] ergab, daß 100% Bruchwahrscheinlichkeit in guter Näherung 100% Schädigungswahrscheinlichkeit gleichzusetzen ist sowie daß die arcsin √‐Transformation ein geeignetes Modellgesetz zur Beschreibung der Schädigungsverteilung ist.

Aus diesen Feststellungen wird eine effizientere Methode zur Ermittlung des Schädigungsbereiches abgeleitet und beschrieben. Anhand von Zwei‐ und Mehrstufenversuchen werden Überlegungen zum Schädigungsbereich angestellt.
Bewertung von Eigenspannungen bei quasistatischer und schwingender Werkstoffbeanspruchung
Authors: Macherauch E. , Kloos K. H.
Published: December 2004

Assessment of Residual Stresses in Quasi‐statically and Cyclically Loaded Materials

The actual knowledge of residual stresses is extremely extensive (see e.g. [1–8]). Nevertheless, in many cases, the consequences of residual stresses on the mechanical behaviour of materials are still qualitatively assessed by experience. This fact is mainly due to the great expense which is necessary to obtain sufficient quantitative information concerning residual stresses in technical parts. Without such data, however, it is not possible to assess residual stress states objectively.

In modern materials technology, residual stresses are usually applied in a twofold manner. On the one hand, they are used as a mostly uncontrollable argument in the interpretation of unexpected failure. On the other hand, they are utilized as a valuable and cheap tool in improving the strength of components.

It is well established the principally no material states of practical importance exist which are free of residual stresses. Consequently, the evaluation and assessment of residual stresses in technical parts is of great importance. In this respect, special interest is focussed on such residual stress states which improve the materials behaviour under particular loading conditions.

This paper deals with the fundamental aspects of the assessment of statically and cyclically loaded components bearing 1st kind residual stresses. First, some basic principles of the theory of elasticity and the theory of equivalent stresses are outlined. Then, well‐accepted definitions of residual stresses are presented. Afterwards, characteristics of the mechanical resistance of materials are described, which can be determined from simple loading tests. Subsequently, the principles of elementary failure considerations are treated followed by a discussion of the influence of residual stresses on the behaviour of statically loaded components. Typical examples are dealt with. Finally, some basic facts concerning the fatigue behaviour of metallic materials are described, and the consequences of residual stresses on cyclically loaded components are discussed. Presenting characteristic examples, the progress is documented which has recently been achieved in the understanding of the effects of residual stresses on the fatigue behaviour of differently treated materials.
Schwingungsverschleiß – Erscheinungsformen, Prüfmethoden und Abhilfemaßnahmen
Authors: Heinz R.
Published: December 2004

Das charakteristische Merkmal der Verschleißart Schwingungsverschleiß gegenüber anderen Verschleißarten ist die intensive Wechselwirkung zwischen Stofftransport, Schwingungsform und Verschleiß. Insbesondere die Verschleißerscheinungsformen werden stark vom Verbleib oder Abtransport der entstehenden Verschleißpartikel und den Schmierstoffzutrittmöglichkeiten beeinflußt. Eine systematische Behandlung der einzelnen Verschleißerscheinungsformen erleichtert die Analyse von Schadensfällen. Trotz der Systemabhängigkeit des Verschleißes bieten die Methoden der Prüfkette und der Variation der Parameter die Möglichkeit, auch mit Bauteil‐ und Modelltests praxisnahe Prüfergebnisse zu erzielen. In einem Beispiel wird gezeigt, wie man damit die Qualität tribologisch beanspruchter Bauteile systematisch erhöhen kann.
H. F.‐Bias gesputterte TiN‐Schichten zur Verschleißminderung an Grauguß‐Kolbenringen
Authors: Roth Th. , Schröder H.‐J. , Broszeit E. , Kloos K. H.
Published: December 2004

Mit Hilfe des reaktiven Hochfrequenz‐Magnetron‐Kathodenzerstäbungsverfahrens wurden 2,5 m̈m und 6 m̈m starke TiN‐Schichten auf Kolbenringen aus Grauguß abgeschieden.

Zur Untersuchung der Gebrauchseigenschaften dieser Schichten unter den komplexen tribologischen Bedingungen, denen die Bauteilpaarung „Zylinderlaufbuchse – Kolbenring”︁ im gefeuerten Motor unterliegt, wurde ein außermotorisches Prüfverfahren herangezogen.

Der sogenannte Kurz‐Hub‐Versuch bietet die Möglichkeit, bis zu acht Kolbenringe gleichzeitig zu testen.

Die Beachtung der im gefeuerten Motor wirksamen Beanspruchungskomponenten erlaubt eine sehr genaue Simulation der dort vorliegenden Verhältnisse und ermöglicht mit Hilfe des Prüfversuchs, das Verschleißverhalten der Reibpaarung „Zylinder‐Kolbenringlauffläche”︁ so zu bewerten, wie mit einem gefeuerten Prüfstandsmotor.

Die TiN‐beschichteten Ringe wurden mit unbeschichteten Graugußringen und mit hartverchromten Kolbenringen verglichen. Durch den Einsatz einer 6 m̈m starken TiN‐Schicht konnte der lineare Gesamtverschleiß (Ring + Zylinder) gegenüber den unbeschichteten Ringen um 85° und gegenüber den hartverchromten Ringen um 50° verringert werden.

Die Haftung der Schichten auf dem Grauguß erweist sich als sehr gut und wird auch durch Graphiteinlagerungen an der Ringoberfläche unter den vorliegenden Beanspruchungsbedingungen nicht beeinträchtigt.
Spectral analysis of the criteria for multiaxial Random Fatigue
Authors: Grzelak J. , Lagoda T. , Macha E.
Published: December 2004

In the paper the spectral analysis of several fatigue criteria under simple and complex states of stress has been done and limitations appearing while formulating new criteria for multiaxial random loadings have been shown. The presented analysis includes determination, with digital simulation, of probability density function and power spectral density function of the equivalent stress according to three special linear criteria of multiaxial random fatigue and six nonlinear criteria. Calculations were carried out for four kinds of random stress state. It has been shown that mathematical models for the criteria of multiaxial random fatigue formulated as nonlinear combinations of stress state components have unfavourable statistical properties, which make their application for fatigue life determination difficult.
Generalized Fatigue Criterion of maximum shear and normal strains on the fracture plane for materials under multiaxial random loadings
Authors: Macha E.
Published: December 2004

A generalized fatigue criterion for materials under multiaxial random loadings is presented. The criterion is based on the assumption that shear and normal strain on the expected fracture plane – shear strain in one direction on this plane is considered – determine the fracture plane. It has been shown that the well known fatigue criteria of maximum normal strain, maximum shear strain and the criterion of maximum shear and normal strains on the critical shear plane result from the newly formulated criterion.
Corrosion of aluminium in alkaline solutions
Authors: Al‐Suhybani A. A. , Sultan Y. H. , Hamid W. A.
Published: December 2004

The corrosion of Al in NaOH solutions has been investigated using polarization method as well as weight loss method. The effect of various organic and inorganic compounds on the rate of corrosion was studied. The results indicated that the rate of Al corrosion is maximum at [NaOH] ∼4M. Various benzoic acid as well as other organic acids inhibit the corrosion but to different extents depending on the structure. The inhibition is due to adsorption of these acids and not due to neutralizing effect. Some sulpher containing compounds inhibit the corrosion but to lesser extent than acids. Aniline and its derivative are mostly activators for corrosion.
Versuchs‐ und Rechendaten zur Dauerschwingfestigkeit von metallischen Werkstoffen unter mehrachsiger Beanspruchung
Authors: Troost A. , Akin O. , Klubberg F.
Published: December 2004

Vorgestellt wird ein umfangreicher Katalog derzeit verfügbarer Versuchsdaten zur Dauerschwingfestigkeit metallischer Werkstoffe bei zweiachsigen Beanspruchungszuständen mit sinusförmig schwingenden Lastspannungsamplituden, sowie hierzu ermittelte Abweichungsverhältnisse zwischen den Versuchsergebnissen und Rechenwerten, die sich jeweils bei einer rechnerischen Bestimmung der dauerfest ertragbaren Lastspannungen gemäß fünf neueren Festigkeitshypothesen ergeben (die in einer vorausgeschickten Arbeit vorgestellte statistische Analyse dieser Abweichungen hat gezeigt, daß die. „Quadratische Versagenshypothese”︁ QVH gegenüber den anderen Festigkeitshypothesen bevorzugt zur Anwendung empfohlen werden kann). Die anhand genannter Quellen fundamental recherchierte, tabellarisch dargestellte Datensammlung umfaßt insgesamt 530 Versuchsergebnisse (Überlebenswahrscheinichkeit PÜ = 50%) an Metallwerkstoffen (unlegierte und legierte Stähle, NE‐Metall‐Legierungen. Guß‐ und Sinterwerkstoffe) mit detaillierter Angabe der Belastungsparameter (Amplitudenverhältnisse, Mittelspannungen, Phasenverschiebungen).
Verschleiß von TaC‐ und TiC‐Laserdispersionsschichten durch weiche und harte Abrasivstoffe
Authors: Axén N. , Gahr K.‐H. Zum
Published: December 2004

Durch CO2‐Laserstrahlung wurden TiC‐ bzw. TaC‐Teilchen, in den mittleren Größen von 3 μm bzw. 30 μm, in die Oberfläche des Kaltarbeitsstahls 90MnCrV8 eingeschmolzen. Die Matrixhärte der Verbundwerkstoffe wurde durch Wärmebehandlungen variiert. In einem Labortribometer wurden die ha_stoffhaltigen Schichten auf ihren abrasiven Versehleißwiderstand gegen Flint‐oder SiC‐Abrasivstoff mit unterschiedlicher Kornung unter‐sucht.

Durch die Einbettung von Hartstoffteilchen konnte der Verschleißwiderstand im Vergleich zum unbeschichteten Stahl urn mehr als eine Größenordnung verbessert werden. Die Ergebnisse zeigen die Einflüsse der Art und Größe der eingelagerten Hart‐stoffe. der Härte der Stahlmatrix und der Art und Körnung des Abrasivstoffs auf den Abrasivverschleiß. In Abhängigkeit von diesen Parametern werden an Hand von Modellen die experimentellen Ergebnisse diskutiert.
Ein stochastisches, schadensmechanisches Versagensmodell für Komposite
Authors: Will P. , Helbig S.
Published: December 2004

Die Modellierung des Stabilitätsproblems, bei dem es im Resultat nichtlokaler Schädigungen zum Katastrophalen Versagen einer Probe kommt, ist das Ziel der vorliegenden Arbeit. Es wird ein weitgehend strukturunabhängiges Konzept zur quantitativen Interpretation und Vorhersage von nichtlinearen, nominellen Spannungs‐Dehnungskurven geschädigter Werkstoffe wie Konstruktionskeramiken oder intermetallische Verbindungen vorgestellt. Dazu werden schadensmechanische und statistische Methoden kombiniert.
On the strength and stiffness of planar reinforced plastic resins
Authors: Padawer G. E. , Beecher N.
Published: December 2004

The recent history of planar reinforced plastic resins, including glass flake, high modulus ceramic flake, and continuous vapor coated film composites, is reviewed. The theoretical mechanics of both continuous (film) and discontinuous (flake and ribbon) reinforcements are summarized in simple form. A novel set of design curves is presented from which the lower bound requirements for the flake composite constitutents may be read directly. At the same time, the dependence of the composite ultimate strength on the shear strength of the plastic resin matrix is demonstrated.

The mechanical properties of experimental film and flake composites representative of recent work are reported and compared with the theoretical predictions. In conclusion, the potential of planar reinforced plastic resin composites is discussed and found to be significant for applications where low weight and high isotropic stiffness are required, for example in aero‐structural, airfoil, or blade components.
Numerical simulation of injection mold filling
Authors: Harry D. H. , Parrott R. G.
Published: December 2004

This paper illustrates a numerical simulation of polymer flow as applied to the injection molding fill process. The simulation model considers heat conduction and viscous heat generation along with the temperature dependence of the flow parameters to predict fill lengths and fill times of thin constant crossection cavities. This simulation is designed for molding situations where fill is difficult, such as thin cavity sections, long flow length requirements, or difficult‐to‐process materials. The simulation sensitivity is explored by performing experimental molding trials with two different cavity thicknesses. The thinner cavity illustrated a short shot in all cases with the thick cavity completely filling. The simulation accurately distinguishes between the short shot and fill conditions, although significant error is noted for the length prediction of the short shot and the time‐to‐fill of the full shot condition.
Thermal stability of networks containing siloxane linkages
Authors: Shaw M. T. , Tobolsky A. V.
Published: December 2004

The thermal stability of elastomers containing siloxane linkages has been compared using the technique of chemical stress relaxation in an inert environement. Enhancement of the already high stability of the basic poly (dimethyl siloxane) silicone rubber by the substitution of hetero groups in and on the main chain was proved, with the exception of the pendent trifluoroporopyl group. Particulary dramatic was the effect of the mcarborane moiety in the SiB‐2 elastomers which elevated the stability of the siloxane chain by more than 100°C relative to silicone rubber.
Mechanism of ultraviolet degradation and stabilization in plastics
Authors: Deanin R. D. , Orroth S. A. , Eliasen R. W. , Greer T. N.
Published: December 2004

When plastics are used for outdoor applications, they often deteriorate fairly rapidly. Theoretical explanation is based upon absorption of ultraviolet energy, raising some bonds to an energy level which exceeds their stability, and thus initiating their breakdown, usually involving atmospheric oxidation and sometimes hydrolysis as well. This theory is satisfactory for many polymers, but does not explain the instability of some polymers which are transparent to ultraviolet, nor the stability of some polymers which contain ultraviolet‐absorbing and/or unstable groups. Plastics are often stabiliized by addition of ultraviolet reflectors, absorbers, or deactivators, increasing stability sufficiently for outdoor use; theoretical explanation of their protective action is satisfactory when they work, but does not explain their specificity or their failures.
Mixing and residence time distribution in melt screw extruders
Authors: Pinto G. , Tadmor Z.
Published: December 2004

The residence time distribution (RTD) functions were derived for screw extruders, based on the “parallel plate” and curved channel flow models. The results indicate a relatively narrow distribution, and they explain several characteristics of screw extruders. The strain distribution in the fluid across the channel was also derived. With the aid of these two functions an average strain of the fluid leaving the extruder was defined. The resulting weighted‐average total strain (WATS) provides a quantitative criterion to the “goodness of mixing” in extruders.
Sources of variability in laboratory weathering
Authors: Kinmonth R. A. , Saxon R. , King R. M.
Published: December 2004

A statistical study was conducted to determine the significance of the sources of variability in the laboratory (carbon arc) weathering of a light‐stabilized polyester resin system. Color fastness of the resin was evaluated in terms of changes in total color, lightness, and chromaticity. Factors that significantly influenced the results were variability within castings and between batches of resin, location of the specimen within the exposure apparatus, and the storage time prior to testing. The carbon arc instrument provided a relatively insensitive test for evaluating a light‐stabilized polymer system, chiefly because, with a stable polymer, small random variations in response become almost equal to the small change in color developed on exposure.
Thermomechanical studies of polymer deformation II. A thermodynamic analysis of a viscoelastic material in sinusoidal deformation
Authors: Duvdevani I. J. , Biesenberger J. A. , Gogos C. C.
Published: December 2004

In this study, a linearly viscoelastic polyurethane film was subjected to continuous, sinusoidal deformation in a new isothermal deformation calorimeter, whose design details were recently reported (1). Internal energy and entropy of the polymer at each state in the deformation cycle were computed from heat rate and work rate data. This was made possible by using linear viscoelasticity theory to predict the irreversible entropy production. Thermal data were corrected for instrument time lag.
Correlation between steady state flow curve and molecular weight distribution for polyethylene melts
Authors: Shroff Ramesh N. , Shida Mitsuzo
Published: December 2004

This article uses Graessley's theory of viscosity to predict the flow curve for several high‐density and low‐density polyethylene melts using the molecular weight distribution data obtained from the gel permeation chromatograph. The agreement with the experimental flow curve obtained from the Weissenberg rheogoniometer and the Instron rheometer was not quantitative for many high‐density polyethylenes studied here. For the low‐density polyethylenes, it was shown that the agreement between the theory and the experiment was good even though the molecular weight distribution data were not corrected for long‐chain branching. For these samples, the experimental relaxation time τ0 obtained by superposition of the data with the theoretical master curve was of the order of the Rouse relaxation time τR. The systematic increase in the ratio τR/τ0 was ascribed to the increase in the molecular weight or to the increased number of long‐chain branches.
Stress‐time superposition of creep data for polypropylene and coupled glass‐reinforced polypropylene
Authors: Cessna L. C.
Published: December 2004

Glass‐reinforced thermoplastics are being considered in many structural applications and fabricators require design information on these materials. Basic creep data are, in many cases, the most useful for design purposes. The work reported here concerns the development of methods of increasing our efficiency in generating creep data. The methods developed are applicable to polypropylene and coupled, glass‐reinforced polypropylene. A stress‐time superposition procedure has been found valid for extending creep data generated on coupled glass‐reinforced polypropylene at several glass levels and at temperatures of 23 and 80°C.
A theoretical melting model for plasticating extruders
Authors: Donovan R. C.
Published: December 2004

A theoretical model for melting in plasticating extruders is described. Compared to previous models, this model introduces more accurate and less restrictive assumptions, adds a mass balance on the entire channel, and replaces certain approximate solutions by exact solutions. Flow of the solid bed is represented by a solid bed acceleration parameter, SBAP, which permits solid bed acceleration in a screw compression section. New experimental melting data for a variety of screw designs, polymers, and extruder sizes are presented and compared to the theoretical predictions. With the optimum SBAP, reasonably accurate model prediction of the melting profiles is observed for a wide variety of cases.
Uniformity of flow from sheeting dies
Authors: McKelvey James M. , Ito Katsuhiko
Published: December 2004

A numerical method for analyzing the uniformity of flow from sheeting dies is presented. The method assumes that the flow is isothermal and that the material is a power law fluid. A uniformity index is defined and methods are presented which enable die dimensions to be established which will result in a specified uniformity at particular flow rates and pressure drops. The analysis shows that the flow index “n” of the power law is the key parameter determining the uniformity of flow from a sheeting die.
Rheological behavior of two‐phase polymer melts
Authors: Han C. D. , Yu T. C.
Published: December 2004

Rheological behavior of dispersed two‐phase polymer melts has been investigated by means of a capillary rheometer. The two‐phase systems chosen for study were blends of two polymers: high‐density polyethylene and polystyrene, which are incompatible in the molten state. In order to investigate the state of dispersion, photographs were taken of the microstructure of extrudate samples, showing that the polystyrene forms long fibers or droplets as a discrete phase dispersed in the polyethylene which forms a continuous phase. Measurements were made of the axial pressure distributions of the two‐phase molten polymers flowing through circular tubes, which permit one, according to the theory advanced by Han, to determine viscous and elastic properties of the melts. Also measured was melt die swell ratio. It has been found from the two independent experimental techniques that there exist a maximum and/or minimum elastic property at a certain blending ratio, and that the elastic property decreases first with L/D ratio of a capillary and then levels off.
Cold rolled ABS. Part 1: The effect of rubber particle size on the tensile properties of ABS before and after cold rolling
Authors: Grancio M. R.
Published: December 2004

The effect of rubber particle size on the tensile properties of rolled and unrolled acrylonitrile‐butadiene‐styrene has been studied by considering model systems consisting of mixtures of a small particle (0.1 micron diam) rubber, S, and a large particle (0.56 micron diam) rubber, L, in an SAN matrix. Before rolling, tensile toughness is characterized by crazing. While both rubber induce matrix crazing, ABS systems containing only the S rubber exhibits early failure due to crack formation, before crazing is propagated very far along the tensile axis. The inefficiency of the small particle rubber is interpreted in terms of high composite yield stress and insufficient distance between particles to allow craze branching. The efficiency of the small particle rubber is improved via the addition of a small amount of large particle, L, rubber to the composite or by a slight degree of cold rolling, both of which enhance craze propagation in the tensile direction. With further rolling, the tensile deformation mode changes from one of localized crazing, which is propagated, to one of uniform deformation, which occurs without crazing.
Predicting melt flow instability from a criterion based on the behavior of polymer solutions
Authors: Boger D. V. , Williams H. Leverne
Published: December 2004

A criterion, based on the behavior of polymer solutions, is developed and applied for the prediction of the onset of flow anomalies observed at the capillary entrance for polymer melts. It is shown that a direct correspondence exists between the flow anomalies observed for polymer solutions and polymer melts. The onset of these anomalies can be correlated with a critical Weissenberg number which is consistent with the equality of the shear wave velocity and friction velocity. This critical condition can be employed to derive expressions useful for predicting the critical recoverable shear and critical shear stress for melt fracture.
Some aspects of orientation in injection molded objects
Authors: Wales J. L. S. , Van Leeuwen Ir J. , Van Der Vijgh R.
Published: December 2004

The birefringences of injection molded plates and the birefringence during steady, isothermal shear flow were compared for some amorphous polymers. The materials studied were a polystyrene, a “toughened” polystyrene and an acrylonitrile‐butadiene‐styrene copolymer. The birefringence of the plates, notably the maximum value for the average over the thickness was found to be related to the shear stress at the cavity wall that had occurred during the mold filling process. This relationship was independent of temperature. To a good approximation, it was also the same as the relationship between the flow birefringence and the shear stress at the wall in isothermal channel flow. It thus appears that the anisotropy of injection molded objects is dominated by the shear stresses during the mold filling process regardless of the temperature and of the macroscopic rate of deformation.
Microfibers within fibers: A review
Authors: Tucker Paul , George Waller
Published: December 2004

Literature relating to the fundamental nature of the fibrous state is reviewed with the goal of illustrating evidence for the existence of a possibly fundamental morphological unit, the elemental microfiber or fibril. Following a short summary of the rather well documented situation in natural fibers, the problem of the microfiber in synthetic fibers is probed in terms of phenomena in solution and bulk polymeric systems. The reviewed literature indicates the existence of unique, elemental microfibers in synthetic fibers is largely tenuous; however, there is wide evidence of the existence of complex elongated structures axially aligned within macrofibers which future work may resolve into a central microfiber. The structural complexity appears to simplify for transformations occurring in high shear fields. This review covers articles through 1971, and it is notable that in 1971 approximately 100 articles of high relevance appeared in major journals.
Block and graft polymers their synthesis, especially by living polymer technique, and their properties
Authors: Szwarc Michael
Published: December 2004

The various structures encountered in block and graft polymers are reviewed and a nomenclature useful for the description of these macromolecules is proposed. The concept of living polymers is elucidated and its ramifications discussed. It is shown how greatly the control of polymerization and the uniformity of the products is improved when living polymers are used as the reagents. Their application in the synthesis of block and graft polymers is illustrated by numerous examples. Other synthetic techniques yielding block and graft polymers are briefly sketched, their advantages and shortcomings being considered. Properties of block and graft polymers are described, special attention being devoted to the problems of mesomorphic phases and to the morphology of block polymers. The incompatibility phenomena observed in block and graft polymer systems are compared with those encountered in studies of the polymeric blends.

Finally, the present and future applications of block and graft polymers are considered and their potential evaluated.
Mechanical relaxation phenomena in polyimide and poly(2,6‐dimethyl‐p‐phenylene oxide) from 100°K to 700°K
Authors: Lim T. , Frosini V. , Zaleckas V. , Morrow D. , Sauer J. A.
Published: December 2004

Existing dynamic mechanical relaxation data on two polymers containing aromatic groups in the backbone chain, viz., polyimide PI, and poly(2,6‐dimethyl‐p‐phenylene oxide), PDMPO, are reviewed and new data bearing on specimen purity and water content are presented. It is demonstrated that three separate relaxation processes are normally present in both polymers in the temperature range from about 100–400°K. The lowest temperature relaxation, designated γ, occurs in the 100–180°K range and is considered to arise from limited rotational oscillation of some phenylene rings about the 1,4 axis. Another relaxation process, designated β arises from the presence of water in the polymer. Its strength increases with increase of water content, its activation energy is about 10–12 kcal/mole, and it occurs in the 180–190°K range at 1 Hz. A higher strength secondary glass relaxation process, designated β*, occurs in the 280–400°K range at usual measuring frequencies (1 Hz to 104 Hz). This relaxation is thought to be associated with the combined reorientational motion, of rings and connecting atoms of the monomer unit in “defect” regions, or regions of poor chain packing. As such, its position is affected by sample history. Both polymers also show a rise in damping in the high temperature region indicative of additional main chain motions. In addition to the above relaxations, PDMPO shows a δ‐relaxation below liquid nitrogen temperatures, associated with onset of Me rotation and PI shows an additional small relaxation near 500°K.
Kinetics and thermal characterization of thermoset cure
Authors: Kamal M. R. , Sourour S.
Published: December 2004

The differential scanning calorimeter (Perkin‐Elmer DSC‐1) is used to characterize the cure of a general‐purpose polyester during isothermal and scanning experiments. The technique is based on a new proposed model for the kinetics of isothermal cure. The model yields results which are in good agreement with experimental isothermal rate of reaction and integral heat of reaction data. It also gives some information about the residual reactivity of the sample after an isothermal cure experiment. With the aid of the proposed kinetic model, it is possible to obtain integral heats of reaction and rates of heat generation at different temperatures during a scanning experiment. The difference between the rate of heat input to the sample and the heat of reaction at any instant during scanning may be used to calculate the specific heat of the sample at the same instant. Specific heat data show two maxima during each scanning experiment. These maxima may be associated with transitions occurring during cure in the melt and rubbery states.
Synergistic interaction in zinc/epoxy/phosphite stabilization of polyvinyl chloride
Authors: Deanin Rudolph D. , Foss Robert M. , Gilbert Paul G. , Guerard Ronald F. , Muccio Edward A.
Published: December 2004

Zinc laurate was a powerful but short‐lived primary stabilizer. Epoxidized soybean oil, catalyzed by a trace of zinc, was a fairly good primary stabilizer. Organic phosphite ester served primarily to prevent premature failure due to zinc; phosphite/zinc mol ratio of 4.5/1 was optimum. These combined effects are consistent with present theories of stabilizer synergism, and also suggest some further possible mechanisms. Practically, the 3‐component system offers a low‐cost, efficient, non‐toxic stabilizer for plasticized polyvinyl chloride.
Flow of polymer melts in a disc‐type extruder and in rotational devices of the “cone‐plate” and “plate‐plate” type
Authors: Kocherov V. L. , Lukach Yu. L. , Sporyagin E. A. , Vinogradov G. V.
Published: December 2004

The flow pattern of a polyethylene melt in the working gap of a disc‐type extruder has been visualized. It is shown that there is complex circulating flow in the working gap of the extruder. The flow lines are spirals of Archimedes. An investigation into the qualitative picture of the flow of a polyethylene melt in rotational devices of the “plate‐plate” and “cone‐plate” type showed that in such devices a complex circulating flow is also realized and the flow lines are spirals of Archimedes.
Chlorinated polyethylene modification of blends derived from waste plastics Part I: Mechanical behavior
Authors: Paul D. R. , Locke C. E. , Vinson C. E.
Published: December 2004

Recycling of waste plastics as a blend of generic types is attractive since a difficult separations problem is avoided. However, blends of incompatible polymers are frequently very brittle and cannot be considered for many applications. Additives which modify the blend to give it ductility may provide a solution to this problem. Chlorinated polyethylene (CPE) made by a slurry process has been suggested for this application by Schramm and Blanchard. Further documentation of the effectiveness of this approach is given here. Addition of CPE to such a blend generally increases the elongation at break and the energy to break very dramatically with ordinarily some loss in strength and modulus. This approach works most effectively in blends of high polyethylene and poly(vinyl chloride) content. Three grades of CPE were studied here which revealed that the specific structure of the CPE molecule is a factor. The effectiveness of CPE for blend modification is believed to derive from the graded molecular structure acquired during chlorination.
Flow and heat transfer in screw extruders: I. A variational analysis applied in helical co‐ordinates
Authors: Nebrensky J. , Pittman J. F. T. , Smith John M.
Published: December 2004

A variational analysis is applied in helical co‐ordinates to the problem of a developed, steady‐state flow in a screw extruder. The functional involves only two dimensionless coordinates and is suitable for minimisation, e.g. by the finite element method. It is applicable to non‐isothermal, purely viscous flows and contains terms representing effects of inertia, convective and conductive transport of heat, pressure gradient, and viscous dissipation. The analysis takes account of the true helical geometry and involves assumptions only in taking the fluid density, specific heat and thermal conductivity of the fluid to be constant, in regarding the fluid to be homogeneous and isotropic, and in simplifying the pressure distribution.
Yielding of polycarbonate and polysulfone in creep and stress‐strain
Authors: Matz David J. , Guldemond William G. , Cooper Stuart L.
Published: December 2004

A modified Eyring rate expression based on an asymmetrical potential energy barrier is used to predict the onset of plastic yield in glassy polymers. Equations for the prediction of plastic yield delay times in creep and yield stresses in constant rate of strain testing are developed and compared to experimental data for samples of polycarbonate and polysulfone with various thermal histories. The two equations accurately fit the experimental results for a suitable choice of parameters. Parameters from the creep data can be used to predict yield stress values in constant rate of strain testing. Variation in simple thermal history changes the model parameters in a way that is qualitatively accounted for from a physical interpretation of the constants.
Differential scanning calorimetry of the epoxy cure reaction
Authors: Prime R. Bruce
Published: December 2004

From a review of the literature it is shown that kinetics from programmed heating rate experiments are often in serious disagreement with published isothermal data. In every case, including the present, the dynamic kinetic parameters measured on epoxies are significantly larger than the isothermal. Use of a dynamic rate equation provides good agreement between the two experiments. It is also shown that the Kissinger method is correct when applied to DSC of epoxies.
Correlation between uniaxial and shear creep of thermoplastics
Authors: Benham P. P.
Published: December 2004

Creep data in uniaxial tension, compression and shear on PVC, PMMA, and PP sheet were used to test analytical correlating procedures. It was shown that shear and uniaxial creep could be closely related using the concept of shear stress and shear strain on octahedral planes. This correlating procedure was only effective if due allowance was made for the different creep response in simple tension and compression for each of these materials. It was also shown that the relationship between the viscoelastic creep moduli and strain ratio, which is stress and time dependent, has the same form as the analogous relationship between the linear elastic constants.
Gel permeation chromatography: A guide to data interpretation
Authors: Evans J. M.
Published: December 2004

The importance of data produced by gel permeation chromatography (GPC) in polymer engineering is emphasized. The steps involved in deriving a differential molecular weight distribution curve (dMWD) from the chromatogram obtained by GPC are outlined. Each step is described, indicating its importance. Several viscosity‐molecular weight relationships, useful in the production of relevant calibration curves from the polystyrene calibration, are included. The presentation of results and experimental procedures are given.