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  • 1
    Electronic Resource
    Electronic Resource
    Uniaxial deformation of bridging polymer systems: A Monte Carlo study (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 7792-7801 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A new approach for the equilibrium deformation of three-dimensional chains, that are bigrafted to parallel planes is presented. The underlying lattice Monte Carlo algorithm is the bond fluctuation model. In addition to the excluded-volume interaction of this a priori athermal algorithm, we incorporated external potentials in order to enable direct detection of forces. The whole deformation process is split up into a series of separate steps. Each step consists of a generation process and subsequent relaxation procedures. Stress and strain are simultaneously calculated as time-averaged quantities of sufficiently equilibrated systems. Stress–strain relations ranging from compression to the highly stretched regime were simulated by variation of both chain length, N, and grafting density, σ. In the high-density limit the simulation data agree perfectly with a simple one-dimensional theory. The N and σ dependency of the distance, h0(N,σ), of grafting planes at vanishing force is in qualitative agreement with theoretical predictions for an intermediate regime of σ. The simulated force–length relations are in satisfactory agreement with current scaling predictions. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473779
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  • 2
    Electronic Resource
    Electronic Resource
    The distribution function of internal distances of a single polymer chain with excluded volume in two and three dimensions: A Monte Carlo study (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 351-358 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The probability distribution functions Ps(r) of the distance r between the end points of subchains of a single excluded volume chain in two and three dimensions were studied using the bond-fluctuation model. The index s refers to three principle cases. Case s=0: the subchain is identical to the whole chain. Case s=1: the subchain constitutes one extremity of the whole chain. Case s=2: the subchain belongs to the central part of the whole chain. It is shown that the data can be described by the functions fs(x)∼xθs for small x and fs(x)∼xκs exp(−Dsxδs) for large x, x being the scaled distance. All exponents θs, κs, and δs were calculated and compared with existing values in the literature. In two dimensions a crossover between θs and κs was detected whereas in three dimensions θs(approximately-equal-to)κs within statistical errors. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.470834
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  • 3
    Electronic Resource
    Electronic Resource
    The collapse transition of a single polymer chain in two and three dimensions: A Monte Carlo study (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 3373-3385 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The collapse transition of a single polymer chain in two and three dimensions was studied using the bond-fluctuation model. The obtained exponents ν of the scaling law 〈S2N〉∼N2ν agree with values proposed in the literature as well as above, at and below the aitch-theta-temperature Taitch-theta. Transition curves and scaling analysis plots are presented. The scaling function α3SτN1/2 vs τN1/2 has a pronounced maximum before leveling off in the fully collapsed regime in accordance with the theory [α2S=〈S2N〉/〈S2N〉aitch-theta, τ=||(T−Taitch-theta)/Taitch-theta||]. An analyzing of the subchain distances leads to disagreements with the blob model. The subchains are locally swollen for T(approximately-greater-than)Taitch-theta and shrunken for T〈Taitch-theta. The probability distribution function of internal distances for T≥Taitch-theta can be described by scaling functions of the form fs(x)∼xκs exp(−Dsxδs) for large x, x being the scaled distance. In contrast for T〈Taitch-theta none of these functions describe the data. The dynamic properties above Taitch-theta are in agreement with the Rouse model, but below Taitch-theta differences occur; the center of mass diffusion becomes anomalous and the relaxation times rise with a power law in N of the form τi(N)∼N2+3/d (d being the dimension of space). © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471041
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  • 4
    Electronic Resource
    Electronic Resource
    Thermoelastic behaviour of polyethylene terephthalate on approaching the glass transition range (1986)
    Springer
    Colloid & polymer science 264 (1986), S. 236-240 
    Details
    ISSN: 1435-1536
    Keywords: Polyethylene terephthalate ; extension ; deformation calorimetry ; thermodynamics of deformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The mechanical and thermal properties of the simple linear reversible extension of a solid can be well described by means of Young's modulus and linear thermal expansion coefficient. In this paper it is shown that on stretching near the glass transition temperature the temperature dependence of Young's modulus must also be taken into account.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01414959
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  • 5
    Electronic Resource
    Electronic Resource
    Die Volumenaufweitung beim uniaxialen Dehnen gefüllter Netzwerke (1984)
    Springer
    Colloid & polymer science 262 (1984), S. 177-181 
    Details
    ISSN: 1435-1536
    Keywords: Dilatometer ; Dehnung ; Elastomere ; Füllstoffe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Abstract A model is presented which allows one to calculate the increase in volume during uniaxial extension of a matrix containing a spherical filler. A simple relationship between volume increase and strain is found, where the filler concentration enters as the only parameter. Measurements on a model substance confirm this calculation. On the other hand, investigations of a carbon-black filled rubber show that the filler causes no additional volume increase over and above that for unfilled rubber. In the case of carbon-black filled rubber, however, straininduced crystallization sets in at lower degrees of elongation. This effect can be clearly observed by means of strain dilatometry.
    Notes: Zusammenfassung Es wird ein Modell vorgestellt, das es gestattet, die Volumenaufweitung zu berechnen, die beim unaxialen Dehnen einer Matrix mit kugelförmigen Füllstoffpartikeln auftritt. Es wird ein einfacher Zusammenhang zwischen Volumenaufweitung und Dehnung gefunden. Das relative Volumen nimmt mit der Dehnung zu, wobei der Füllstoffgehalt als einziger Parameter eingeht. Messungen an einer Modellsubstanz bestätigen die Richtigkeit der Rechnung. Bei der Untersuchung von rußgefülltem Gummi ergibt sich dagegen, daß der Füllstoff keine zusätzliche Volumenaufweitung gegenüber dem ungefüllten Gummi bewirkt. Wohl aber setzt bei rußgefülltem Kautschuk die dehnungsinduzierte Kristallisation früher ein als im ungefüllten System. Dies läßt sich mit Hilfe des Dehnungsdilatometers gut beobachten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01458958
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  • 6
    Electronic Resource
    Electronic Resource
    Network properties of mixtures of protonated and deuterated polyethylene (1988)
    Springer
    Colloid & polymer science 266 (1988), S. 235-240 
    Details
    ISSN: 1435-1536
    Keywords: Protonated and deuterated polyethylene ; mixtures ; crosslinking ; crystallinity ; entropy ; enthalpy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Mixtures of protonated and deuterated polyethylene were irradiated in the melt. The degree of crystallinity, the degree of crosslinking, as well as the enthalpyΔH and the melting pointT M were determined. No significant differences in the degree of crosslinking between protonated and deuterated chains were found. The mass specific entropyΔS of the uncrosslinked samples remained constant and independent of the deuterium concentration. For the crosslinked samples, a netpoint entropy was postulated. A weaker Van der Waals interaction could explain the decrease in melting temperature by deuteration (for weakly crosslinked samples).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01452585
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  • 7
    Electronic Resource
    Electronic Resource
    Die kalorimetrische Erfassung der Dehnungskristallisation Polymerer (1970)
    Springer
    Colloid & polymer science 241 (1970), S. 1075-1079 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Summary Natural rubber belongs just like polyisobutylene to the class of polymers that crystallize well when stretched. The heat development arising out of the crystallization may be especially well be determined by means of the stretching calorimeter. It is essential that the registered heat curves will before be corrected as far as an erroneous time factor is involved. Then from the corrected curves the crystallization heat may be separated from the entropy belonging to the statistical orientation of the chains. This way the time factor involved for the crystallization as well as the time factor involved in melting of the crystallites when released may be well determined. The rate of crystallization and also the degree of crystallization may be possible with great precision-even if very small.
    Notes: Zusammenfassung Naturkautschuk gehört ebenso wie Polyisobutylen zu denjenigen Polymeren, die beim Verstrecken gut kristallisieren. Die die Kristallisation begleitende Wärmeentwicklung kann im Verstreckungskalorimeter mit sehr hoher Empfindlichkeit erfaßt werden. Wesentlich dafür ist, daß man die Registrierkurven für den die die Apparatur liefert, in bezug auf ihre zeitliche Verzeichnung entzerrt. Aus den entzerrten Kurven läßt sich die Kristallisationswärme von der zur statistischen Orientierung der Ketten gehörigen Entropiewärme abtrennen und auf diese Weise sowohl der zeitliche Verlauf der Kristallisation als auch bei Entlastung der zeitliche Verlauf des Schmelzens der Kristallite verfolgen. Der Kristallisationsgrad läßt sich mit erheblicher Genauigkeit, selbst bei sehr geringen Anteil, bestimmen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02137415
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  • 8
    Electronic Resource
    Electronic Resource
    Zustandsänderungen von polymeren Netzwerken bei Orientierung (1973)
    Springer
    Colloid & polymer science 251 (1973), S. 892-900 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Summary Studies of the oriented crystallization on axial stress have shown that crystallization during stretching follows to a different mechanism than in the extended state. The final degree of crystallization is found to be dependent on temperature and elongation. The dependence on elongation does not followFlorys theory of crystallization induced by stretching polymeric networks. However, separating the crystallization into one process developing during stretching and another in the extended state shows that this theory applies to the latter one. Time analysis of the oriented crystallization on axial stress yields similar results. This crystallization cannot be described as one uniform process by the theory ofAvrami. However, considering two separate processes each can be described quantitatively with sufficient accuracy. The stress induced crystallization is controlled by a homogeneous grow three-dimensionally. After termination of stretching no further nuclei are formed. Further crystallization is restricted to one-dimensional growth of existing crystallites in the direction of stress. Both mechanisms of crystallization are independent of temperature, elongation and degree of crosslinking.
    Notes: Zusammenfassung Untersuchungen der Dehnungskristallisation mit der kalorischen Methode zeigen, daß während der Dehnung die Kristallisation nach einem anderen Mechanismus abläuft als im gedehnten Zustand. Der Kristallisationsgrad am Ende des gesamten Dehnprozesses wird temperatur- und dehnungsabhängig gefunden. Seine Abhängigkeit von der Verlängerung läßt sich jedoch nicht mit der vonFlory entwickelten Theorie der Kristallisation von uniaxial orientierten polymeren Netzwerken beschreiben. Trennt man die Kristallisation in einen Anteil, der sich während der Dehnung entwickelt und in einen zweiten, der die anschließenden Vorgänge in der gedehnt gehaltenen Probe erfaßt, auf, dann stimmen im zweiten Fall Theorie und Experiment gut überein. Die zeitliche Analyse der Gesamtkristallisation zeigt das gleiche Verhalten. Die Kristallisation läßt sich quantitativ nicht mit den vonAvrami entwickelten Zeitgesetzen als einheitlichen Prozeß beschreiben. Betrachtet man indes wieder zwei getrennte Vorgänge, wird für jeden eine genügend gute quantitative Beschreibung gefunden. Die dehnungsinduzierte Kristallisation wird durch eine homogene Keimbildung gesteuert. Die sich während der gesamten Dehnung bildenden Keime wachsen dreidimensional zu Kristallen heran. Beendet man die Verstreckung, werden keine weiteren Keime gebildet. Die weiter fortdauernde Kristallisation ist auf longitudinales Wachstum der vorhandenen Kristallite in Verstreckrichtung beschränkt. Beide Kristallisationsmechanismen sind unabhängig von der Temperatur, vom Dehnungs- und Vernetzungsgrad.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01498916
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  • 9
    Electronic Resource
    Electronic Resource
    Zustandsänderungen von polymeren Netzwerken bei Orientierung (1973)
    Springer
    Colloid & polymer science 251 (1973), S. 679-688 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Summary Changes of internal energy have been determined for cross-linked natural rubber elongated in the amorphous state by means of a deformation calorimeter. The parameters studied have been the temperature, elongation ratio and the degree of cross-linking. It is shown that the deformation calorimeter is more able to measure in a very sensitive way the change of internal energy than stress-temperature measurements performed ordinarily. In the range of small elongation ratios (α〈3) the increase of the internal energy was found to be continuous and proportional to the degree of cross-linking and independent of temperature below 50 °C whereas a discontinuous change in the slope was found near 50 °C. The temperature coefficient of the unperturbed chaindln 〈 r 0 2 〉/dT has been determined by means of the contribution of internal energy to the elastic forcef e /f. The coefficient was found to be temperature-dependent. Values of the temperature coefficient are approximately 1,2·10−3 Grad−1 below 50 °C and 0,55·10−3 Grad−1 above 50 °C. The potentials of hindered rotation about bonds of the chain backbone responsible for the internal energy are calculated.
    Notes: Zusammenfassung Die Änderung der Inneren Energie von vernetztem Naturkautschuk bei uniaxialer Dehnung wird mit dem Verstreckungskalorimeter bestimmt. Parameter sind die Temperatur, der Dehnungs- und der Vernetzungsgrad. Es zeigt sich, daß das Verstreckungskalorimeter die Änderung der Inneren Energie sicherer und empfindlicher zu erfassen gestattet als bisher übliche Kraft-Temperatur-Messungen. Bei kleinen Dehnungen (α〈3) ist die Erhöhung der Inneren Energie direkt proportional zum Vernetzungsgrad der Proben und weitgehend temperaturunabhängig, um sich in der Umgebung von 50 °C sprunghaft zu ändern. Aus dem energieelastischen Beitrag zur Gesamtkraftf e /f wurde der Temperaturkoeffizient der ungestörten Ketten dln〈r 0 2 〉/dT und seine Änderung mit der Temperatur bestimmt. Unterhalb von 50 °C hatte er einen Wert von etwa 1,2 · 10−3 Grad−1, oberhalb fiel er auf 0,55 · 10−3 Grad−1 ab. Die für die Erhöhung der Inneren Energie verantwortlichen Potentiale der behinderten Rotation um Bindungen der Hauptkette werden berechnet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01498468
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  • 10
    Electronic Resource
    Electronic Resource
    Über das Schmelzen von dehnungskristallinen Anteilen bei Kautschuk (1974)
    Springer
    Colloid & polymer science 252 (1974), S. 330-332 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01551156
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