Intermolecular Forces and Chain Flexibilities. IV. Internal Pressures of Polyethylene Glycol in the Region of Its Melting Point

1963 ◽  
Vol 36 (4) ◽  
pp. 1000-1002
Author(s):  
G. Allen ◽  
D. Sims
Keyword(s):  
Glass Transition ◽  
Polyethylene Glycol ◽  
Melting Point ◽  
Internal Pressure ◽  
Intermolecular Forces ◽  
Commercial Sample ◽  
Experimental Support ◽  
Polymeric Glasses ◽  
Chain Conformations ◽  
Internal Pressures

Abstract Experimental support for the suggestion (Part III), that the freezing-in of chain conformations is a major factor contributing to the low values of internal pressure found in polymeric glasses compared with the glass transition regions for corresponding rubbers, is advanced as a result of tests on a commercial sample of polyethylene glycol. The reliability of the results is considered.

Intermolecular forces and chain flexibilities in polymers: II. Internal pressures of polymers

Polymer ◽  
1960 ◽  
Vol 1 ◽  
pp. 467-476 ◽  
Author(s):  
Geoffrey Allen ◽  
Geoffrey Gee ◽  
Duryodhan Mangaraj ◽  
David Sims ◽  
Geoffrey J. Wilson
Keyword(s):  
Intermolecular Forces ◽  
Internal Pressures

Strong Liquid Behavior of Zr-Ti-Cu-Ni-Be Bulk Metallic Glass Forming Alloys

1996 ◽  
Vol 455 ◽  
Author(s):  
Ralf Busch ◽  
Andreas Masuhr ◽  
Eric Bakke ◽  
William L. Johnson
Keyword(s):  
Glass Transition ◽  
Melting Point ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Supercooled Liquid ◽  
Glass Transition Region ◽  
Glass Forming ◽  
Liquid Behavior ◽  
Metallic Liquids ◽  
Microscopic Origin

ABSTRACTThe viscosities of the Zr46.75Ti8.25Cu7.5Ni10Be27.5 and the Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass forming liquids was determined from the melting point down to the glass transition in the entire temperature range of the supercooled liquid. The temperature dependence of the viscosity in the supercooled liquid obeys the Vogel-Fulcher-Tammann (VFT) relation. The fragility index D is about 20 for both alloys and the ratio between glass transition temperature and VFT temperature is found to be 1.5. A comparison with other glass forming systems shows that these bulk metallic glass formers are strong liquids comparable to sodium silicate glass. Furthermore, they are the strongest among metallic glass forming liquids. This behavior is a main contributing factor to the glass forming ability since it implicates a higher viscosity from the melting point down to the glass transition compared to other metallic liquids. Thus, the kinetics in the supercooled liquid is sluggish and yields a low critical cooling rate for glass formation. The relaxation behavior in the glass transition region of the alloys is consistent with their strong glassy nature as reflected by a stretching exponent that is close to 0.8. The microscopic origin of the strong liquid behavior of bulk metallic glass formers is discussed.

Elastomer Structures and ‘Cold Crystallization’

1979 ◽  
Vol 52 (1) ◽  
pp. 207-212 ◽  
Author(s):  
M. Bruzzone ◽  
E. Sorta
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Melting Point ◽  
Natural Rubber ◽  
Crystallization Rate ◽  
Cold Crystallization ◽  
Structural Defects ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Abstract In a great number of applications an ideal elastomer should satisfy, to a certain extent, both of the following requirements: (1) nearly instantaneous crystallization upon application of strain (strain induced crystallization) and (2) slow or no crystallization when cooled at the temperature of maximum crystallization rate (cold induced crystallization). A noteworthy case of (2) is elastomer crystallization in a strained state. The connection between the points (1) and (2) has not been clearly understood up to now, but it is known that some crystallizable elastomers fulfil the requirements of both (1) and (2) better than others. From an experimental point of view, cold induced crystallization kinetics are substantially easier to measure than those of very fast strain induced crystallization. The phenomenon of cold induced crystallization in natural rubber, NR, has been known since the very beginning of elastomer technology and the tendency of natural rubber to crystallize by cooling has been overcome by crosslinking it with sulphur (vulcanization) without impairing its ability to crystallize by stretching (Goodyear, 1836). The synthesis of cis-polyisoprenes (IR) and cis-polybutadiene (BR) of different microstructural purity (different cis content) gave the possibility of changing the crystallization rate. It has also been reported that the very fast cold crystallization of trans-polypentenamer (TPA) could be reduced by lowering the trans content. The same fact had been observed earlier for trans-polychloroprene. There is a general agreement in postulating that the reduction of the crystallization rate, obtained either by cross-linking or by chain regularity reduction, can be linked with the lowering of the melting point. In both cases the low level of structural defects introduced in the chains does not affect the glass transition temperature in such a way as to vary the crystallization rate. The aim of this paper is to emphasize the importance of the variations of the glass transition temperature and melting point on the elastomeric cold crystallization rate and the way these may be used in planning new elastomer structures.

Glass transition and thermodynamic state of densified polymeric glasses

Polymer ◽  
1978 ◽  
Vol 19 (6) ◽  
pp. 659-663 ◽  
Author(s):  
I.G. Brown ◽  
R.E. Wetton ◽  
M.J. Richardson ◽  
N.G. Savill
Keyword(s):  
Glass Transition ◽  
Thermodynamic State ◽  
Polymeric Glasses

Thermal Analysis of Nomex® and Kevlar® Fibers

1977 ◽  
Vol 47 (1) ◽  
pp. 62-66 ◽  
Author(s):  
J. R. Brown ◽  
B. C. Ennis
Keyword(s):  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Glass Transition ◽  
Melting Point ◽  
Transition Region ◽  
High Temperatures ◽  
High Performance ◽  
Polymer Melt ◽  
Glass Transition Region ◽  
Dta Curves

DTA, TG, and TMA curves of commercial Kevlar® 49 and Nomex® fibers have been used to assess their behavior at high temperatures. The fibers lost absorbed water around 100°C, and a glass transition was reflected in the DTA and TMA curves in the region of 300°C. Difficulties in the interpretation of DTA and TMA curves in the glass-transition region and in the assignments of Tv‘s for these high-performance fibers are discussed. Whereas Kevlar 49 showed both a crystalline melting point (560°C) and a sharp endothermal thermal decomposition (590°C), Nomex showed only the latter (440°C) and no evidence of melting from the DTA curves. The endothermal decomposition peaks apparently correspond to “polymer melt temperatures” reported for related materials, and correlate well with the TG and TMA features. During thermal analysis of Kevlar 49, oxidation occurs more readily than thermal decomposition, but the latter predominates for Nomex. Differences between dyed and undyed Nomex were due to differences in yarn constitution.

Glass transition at the polystyrene/polyethylene glycol interface observed via contact angle measurements

2019 ◽  
Vol 51 (5) ◽  
pp. 481-488 ◽  
Author(s):  
Takashi Sasaki ◽  
Kazuaki Hiraki ◽  
Aizzahtul Athirah ◽  
Kodai Matsuta ◽  
Natsuki Takeuchi
Keyword(s):  
Contact Angle ◽  
Glass Transition ◽  
Polyethylene Glycol ◽  
Angle Measurements ◽  
Contact Angle Measurements

scholarly journals Six ‘Must-Have’ Minerals for Life’s Emergence: Olivine, Pyrrhotite, Bridgmanite, Serpentine, Fougerite and Mackinawite

Life ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 291
Author(s):  
Michael Russell ◽  
Adrian Ponce
Keyword(s):  
Free Energy ◽  
Solar System ◽  
Internal Pressure ◽  
Electron Acceptors ◽  
Extraterrestrial Life ◽  
Apparent Absence ◽  
Essential Requirement ◽  
Dissipative Processes ◽  
Planetary Bodies ◽  
Internal Pressures

Life cannot emerge on a planet or moon without the appropriate electrochemical disequilibria and the minerals that mediate energy-dissipative processes. Here, it is argued that four minerals, olivine ([Mg>Fe]2SiO4), bridgmanite ([Mg,Fe]SiO3), serpentine ([Mg,Fe,]2-3Si2O5[OH)]4), and pyrrhotite (Fe(1−x)S), are an essential requirement in planetary bodies to produce such disequilibria and, thereby, life. Yet only two minerals, fougerite ([Fe2+6xFe3+6(x−1)O12H2(7−3x)]2+·[(CO2−)·3H2O]2−) and mackinawite (Fe[Ni]S), are vital—comprising precipitate membranes—as initial “free energy” conductors and converters of such disequilibria, i.e., as the initiators of a CO2-reducing metabolism. The fact that wet and rocky bodies in the solar system much smaller than Earth or Venus do not reach the internal pressure (≥23 GPa) requirements in their mantles sufficient for producing bridgmanite and, therefore, are too reduced to stabilize and emit CO2—the staple of life—may explain the apparent absence or negligible concentrations of that gas on these bodies, and thereby serves as a constraint in the search for extraterrestrial life. The astrobiological challenge then is to search for worlds that (i) are large enough to generate internal pressures such as to produce bridgmanite or (ii) boast electron acceptors, including imported CO2, from extraterrestrial sources in their hydrospheres.

Crystallizable Trans-Butadiene-Piperylene Elastomers

1978 ◽  
Vol 51 (5) ◽  
pp. 907-924 ◽  
Author(s):  
M. Bruzzone ◽  
A. Carbonaro ◽  
L. Gargani
Keyword(s):  
Glass Transition ◽  
Melting Point ◽  
Low Temperature ◽  
Temperature Sensitivity ◽  
General Purpose ◽  
Strain Sensitivity ◽  
Rational Utilization ◽  
Green Strength ◽  
Synthetic Rubber ◽  
Vanadium Based Catalysts

Abstract The synthesis of a crystallizable synthetic rubber based on butadiene and piperylene in the presence of active vanadium-based catalysts is described. This outlet for piperylene (a cocomponent with isoprene of the C5 cut of naphtha crackers) would allow a rational utilization of both monomers present in the same cut and draw the best advantage from the complementary properties of the copolymer described in this work and cis-1,4-polyisoprene. The butadiene units in the copolymer are in the trans-1,4-configuration. The piperylene content giving a good compromise between crystallization at low temperature (temperature sensitivity) and crystallization upon stretching (strain sensitivity) is 30 ± 5 mol%. The copolymer shows outstanding green strength and tack, and it is less prone than high-cis-polybutadiene and trans-polypentenamer to crystallization at low temperature, because of a particular combination of thermodynamic parameters. Among these, melting point and glass transition are somewhat adjustable by controlling the piperylene content in the range specified. The properties of this crystallizable rubber suggest its use as a general-purpose rubber, possibly in combination with other conventional elastomers.

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