Mechanische Relaxation von einkristallinem Eis

Kneser, Hans O.; Magun, S.; Ziegler, G. E.

doi:10.1007/bf00599816

Cited by 24 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Faceting of the large-angle grain boundaries in bicrystals of ice in which misorientation is near to the ideal CSL (<1010)/34.1°) was observed by both optical and X-ray topographic methods. Observed results in section topographs taken before and after deformation revealed that (1) no long-range stress field is associated with the GB in equilibrium, (2) stress fields are generated and extended from the GB facet intersections when a shear stress is applied on the GB plane. These results indicate that the facets are composed of the ideal-CSL lattice plane (1121) and intrinsic GBDs as shown in Figure 9.…”

Section: Discussionmentioning

confidence: 99%

Generation and absorption of dislocations at large-angle grain boundaries in deformed ice crystals

Hondoh¹,

Higashi²

1983

J. Phys. Chem.

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 99%

Generation and absorption of dislocations at large-angle grain boundaries in deformed ice crystals

Hondoh¹,

Higashi²

1983

J. Phys. Chem.

View full text Add to dashboard Cite

“…The relationship between S z and S c can also be found parallel to nonpolymeric liquids that are capable of exhibiting internal configurational changes, known as Kneser liquids [ 10 ]. Domains of cooperativity among the molecules can be considered, within which the molecular relaxation can only occur together simultaneously.…”

Section: Intermolecular Cooperativitymentioning

confidence: 99%

Entropy, free volume, and cooperative relaxation

Matsuoka¹

1997

J. Res. Natl. Inst. Stand. Technol.

View full text Add to dashboard Cite

The high frequency end of the relaxation spectrum for polymer molecules involves the rotation of the segmental bonds. This fast relaxation process, however, cannot take place easily in the condensed state crowded by the densely packed conformers, necessitating the slower cooperatively synchronous relaxation. As the temperature is lowered, the domain of cooperativity grows towards the infinite size at the Kauzmann zero entropy temperature, though actually the system deviates from the equilibrium as the glass transition intervenes typically at 50 K above that temperature. The excess enthalpy and entropy drop faster than predicted by the rotational isomeric states which would reach zero only at 0 K. The real ΔCP is greater than that of the RIS value. The actual volume in excess of the crystalline lattice volume, however, points towards zero at 0 K. Thus, a polymer with higher Tg typically exhibits a lower density and modulus in the glassy state. Since the configurational entropy associated with the free volume is proportional to the logarithm of the latter, the Kauzmann temperature can be scaled by ln M, where M is the algebraic average of the conformer molecular weight. The temperature dependence of the most dominant, i.e., the largest equilibrium domain size will result in the Adam-Gibbs and Vogel equations for the characteristic relaxation time. The cooperative domain distribution leads to the relaxation spectrum that follows a power law. The relationship between the characteristic relaxation time and the rate of physical aging is derived.

show abstract

“…As regards the change for water, Naganuma [5] observed the same phenomenon in his "dynamic spring analysis", in which the mechanical properties of a copper spring coated with the sample are measured with the Vibron (an apparatus for measuring forced tensile oscillations) [6]. Mechanical relaxation phenomenon is also observed in isothermal runs [7] and this change therefore seems to be due to the mechanical relaxation phenomenon in ice.…”

Section: Resultsmentioning

confidence: 85%

Potential temperature standards for torsional braid analysis

Takahashi¹,

Ozawa²

1975

Journal of Thermal Analysis

View full text Add to dashboard Cite

In torsional braid analysis (TBA) the thermocouple junction is not in contact with the specimen, and therefore temperature standards are necessary. However TBA is devised only for application to high polymers, which are not appropriate for standards. The transition and fusion temperatures of several substances of low molecular weight, such as water, o-terphenyl, potassium nitrate and n-azoxyanisole, have been studied by TBA, and their applicability as standards to TBA is discussed. It is found that water, o-terphenyl and potassium nitrate can be used as standards.In thermal analyses, the properties of a sample or the phenomena taking place in it are observed as a function of temperature, so that the accuracy of temperature measurement is very important. Nevertheless, the accuracy is decreased as a result of the measurement being made during heating or cooling of the sample, and a temperature gradient inevitably exists within and around the sample. The Committee on Standardization of the International Confederation for Thermal Analysis has already certified three sets of differential thermal analysis (DTA) standards [1] for comparison of instrumentation; other attempts are now being made to establish other sets of standards for DTA, and appropriate substances for thermogravimetry (TG) are also being searched for.However, the need for TG standards is greater than for DTA standards, because it is difficult for the thermocouple junction to be in contact with the sample in TG. The situation is similar in torsional braid analysis (TBA), because contact between the thermocouple and the sample can not be made in TBA [2]. Furthermore, TBA has mainly been applied to high polymers, and in only a few cases to substances of low molecular weight [3]. High polymers are not suitable as standards, because the transition points and the melting points of high polymers depend on a number of factors, such as thermal history, molecular weight, heating rate, and so on.With the above points in mind, the authors have studied the transitions and meltings of several substances of low molecular weight by TBA. In this paper, the results are reported and the applicability of these substances as standards is discussed.

show abstract

Mechanische Relaxation von einkristallinem Eis

Cited by 24 publications

References 0 publications

Generation and absorption of dislocations at large-angle grain boundaries in deformed ice crystals

Generation and absorption of dislocations at large-angle grain boundaries in deformed ice crystals

Entropy, free volume, and cooperative relaxation

Potential temperature standards for torsional braid analysis

Contact Info

Product

Resources

About