Visualization of Nonequilibrium Properties of a Crystalline Polymer: Formation of Ring-Lite Due to the Gibbs–Thomson Effect and Dark-Ring Due to the Melting Point Inversion

2021 ◽  
Author(s):  
Koji Nishida ◽  
Yuta Hikima ◽  
Tsuyoshi Koga ◽  
Masahiro Ohshima
Keyword(s):  
Melting Point ◽  
Crystalline Polymer ◽  
Thomson Effect ◽  
Dark Ring ◽  
Polymer Formation

Self-Assembly Directed Organization of Nanodiamond During Ionic Liquid Crystalline Polymer Formation

2016 ◽  
Vol 37 (14) ◽  
pp. 1155-1167 ◽  
Author(s):  
Bryan S. Ringstrand ◽  
Sönke Seifert ◽  
David W. Podlesak ◽  
Millicent A. Firestone
Keyword(s):  
Ionic Liquid ◽  
Self Assembly ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Polymer Formation

Thermoelectricity

2004 ◽  
Author(s):  
Robert E. Newnham
Keyword(s):  
Melting Point ◽  
Power Series ◽  
Driving Forces ◽  
Constant Term ◽  
Open Circuit ◽  
Peltier Effect ◽  
Thomson Effect ◽  
Cold Junction ◽  
Different Temperatures ◽  
Physical Phenomena

When two different metals are connected together in a circuit and the two junctions are held at different temperatures, five physical phenomena take place simultaneously. Thermal and electric currents flow in the circuit, giving rise to Joule heating and thermal conduction. The driving forces for these currents are three interrelated thermoelectric phenomena: the Seebeck Effect, the Peltier Effect, and the Thomson Effect. For commonly used thermocouples, a voltage is developed when the junctions are held at different temperatures. In practice, one junction is held at a constant temperature (often the melting point of ice), and the open circuit voltage is measured as a function of the temperature of the second junction. If the reference temperature is 0◦C, then the thermocouple voltage can be expressed as a power series. . . . V = αT + βT2 + γ T3 +· · · , . . . where T is the temperature in ◦C and the coefficients depend on the choice of metals. Data for Cu–Ni and Cu–Fe thermocouples are presented in Fig. 21.2 along with the governing equations. If the cold junction is at a temperature other than 0◦C, it is only necessary to add a constant term. From this it follows that dV/dT at one junction is independent of the temperature of the second junction.

The Melting of Crystalline Polymers

1945 ◽  
Vol 18 (2) ◽  
pp. 256-266
Author(s):  
Elizabeth M. Frith ◽  
R. F. Tuckett
Keyword(s):  
Melting Point ◽  
Amorphous Material ◽  
Crystalline Polymer ◽  
Nonlinear Relationship ◽  
X Ray ◽  
Crystalline Polymers ◽  
Colloid Science ◽  
Stretched Polymers ◽  
Equilibrium Ratio ◽  
Good Agreement

Abstract The thermodynamic equilibrium which exists between crystalline and amorphous polymeric phases is discussed in terms of a fringed micelle model, as indicated by x-ray data. An expression derived for the melting point of a crystalline polymer is found to depend on the proportion θ of amorphous material in the structure: this unsharp melting point depends ultimately on a nonlinear relationship between θ and the free energy of the system. Calculated values of the crystalline amorphous equilibrium ratio over a range of temperature are in good agreement with experimental data. An attempt has been made to extend the calculations to the case of stretched polymers and a qualitative agreement has been found. This work has been carried out in the Department of Colloid Science, Cambridge, and we should like to thank Professor E. K. Rideal for much stimulating criticism. This paper arose out of discussions with Professor Sir R. H. Fowler: his advice and encouragement during its development have been invaluable to us, and we should like to record here our grateful thanks to him.

Shifting of the melting point for semi-crystalline polymer nanofibers

2011 ◽  
Vol 93 (4) ◽  
pp. 46001 ◽  
Author(s):  
A. Arinstein ◽  
Y. Liu ◽  
M. Rafailovich ◽  
E. Zussman
Keyword(s):  
Melting Point ◽  
Crystalline Polymer ◽  
Polymer Nanofibers

Voids in Irradiated Tungsten and Molybdenum

1969 ◽  
Vol 27 ◽  
pp. 190-191
Author(s):  
Robert C. Rau ◽  
Robert L. Ladd
Keyword(s):  
Melting Point ◽  
Fast Neutron ◽  
Neutron Irradiation ◽  
Elevated Temperatures ◽  
Irradiation Temperature ◽  
The Body ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Cubic Metals ◽  
Face Centered

Recent studies have shown the presence of voids in several face-centered cubic metals after neutron irradiation at elevated temperatures. These voids were found when the irradiation temperature was above 0.3 Tm where Tm is the absolute melting point, and were ascribed to the agglomeration of lattice vacancies resulting from fast neutron generated displacement cascades. The present paper reports the existence of similar voids in the body-centered cubic metals tungsten and molybdenum.

Structure-property relations of liquid crystalline polymers

1987 ◽  
Vol 45 ◽  
pp. 460-463
Author(s):  
Linda C. Sawyer
Keyword(s):  
Solid State ◽  
Liquid Crystalline ◽  
Structural Model ◽  
Crystalline Polymer ◽  
Liquid Crystalline Polymers ◽  
Mechanical Anisotropy ◽  
Structure Property ◽  
Preparation Methods ◽  
Crystalline Polymers ◽  
Extended Chain

Recent liquid crystalline polymer (LCP) research has sought to define structure-property relationships of these complex new materials. The two major types of LCPs, thermotropic and lyotropic LCPs, both exhibit effects of process history on the microstructure frozen into the solid state. The high mechanical anisotropy of the molecules favors formation of complex structures. Microscopy has been used to develop an understanding of these microstructures and to describe them in a fundamental structural model. Preparation methods used include microtomy, etching, fracture and sonication for study by optical and electron microscopy techniques, which have been described for polymers. The model accounts for the macrostructures and microstructures observed in highly oriented fibers and films.Rod-like liquid crystalline polymers produce oriented materials because they have extended chain structures in the solid state. These polymers have found application as high modulus fibers and films with unique properties due to the formation of ordered solutions (lyotropic) or melts (thermotropic) which transform easily into highly oriented, extended chain structures in the solid state.

The observation of nano-voids in Au thin films

1987 ◽  
Vol 45 ◽  
pp. 366-367
Author(s):  
William Krakow
Keyword(s):  
Thin Films ◽  
Melting Point ◽  
Present Author ◽  
Stacking Faults ◽  
Damage Threshold ◽  
Ionic Species ◽  
Rare Gases ◽  
Chain Defects ◽  
Vacancy Chains ◽  
Au Thin Films

It has long been known that defects such as stacking faults and voids can be quenched from various alloyed metals heated to near their melting point. Today it is common practice to irradiate samples with various ionic species of rare gases which also form voids containing solidified phases of the same atomic species, e.g. ref. 3. Equivalently, electron irradiation has been used to produce damage events, e.g. ref. 4. Generally all of the above mentioned studies have relied on diffraction contrast to observe the defects produced down to a dimension of perhaps 10 to 20Å. Also all these studies have used ions or electrons which exceeded the damage threshold for knockon events. In the case of higher resolution studies the present author has identified vacancy and interstitial type chain defects in ion irradiated Si and was able to identify both di-interstitial and di-vacancy chains running through the foil.

Observing the relaxation of molecular orientation in sheared liquid crystalline polymer solutions

1990 ◽  
Vol 48 (4) ◽  
pp. 1092-1093
Author(s):  
Wendy Putnam ◽  
Christopher Viney
Keyword(s):  
Molecular Orientation ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Polymer Processing ◽  
Molecular Alignment ◽  
Global Alignment ◽  
Shear Direction ◽  
Axial Strength ◽  
Strength And Stiffness

Liquid crystalline polymers (solutions or melts) can be spun into fibers and films that have a higher axial strength and stiffness than conventionally processed polymers. These superior properties are due to the spontaneous molecular extension and alignment that is characteristic of liquid crystalline phases. Much of the effort in processing conventional polymers goes into extending and aligning the chains, while, in liquid crystalline polymer processing, the primary microstructural rearrangement involves converting local molecular alignment into global molecular alignment. Unfortunately, the global alignment introduced by processing relaxes quickly upon cessation of shear, and the molecular orientation develops a periodic misalignment relative to the shear direction. The axial strength and stiffness are reduced by this relaxation.Clearly there is a need to solidify the liquid crystalline state (i.e. remove heat or solvent) before significant relaxation occurs. Several researchers have observed this relaxation, mainly in solutions of hydroxypropyl cellulose (HPC) because they are lyotropic under ambient conditions.

Sign in / Sign up

Export Citation Format

Share Document