Beta Ray Absorption in Polymers and Determination of First and Second-Order Transition Temperatures

1963 ◽  
Vol 36 (2) ◽  
pp. 459-472 ◽  
Author(s):  
R. Zannetti ◽  
P. Manaresi ◽  
L. Baldi
Keyword(s):  
Phase Transitions ◽  
Natural Rubber ◽  
Good Accuracy ◽  
Second Order ◽  
Order Transition ◽  
Beta Radiation ◽  
Transition Temperatures ◽  
Inorganic Substances ◽  
Second Order Transition

Abstract It is possible to determine the first- and second-order transition temperatures of polymers, copolymers, and other organic and inorganic substances with good accuracy and reproducibility by measuring their absorption of beta radiation. Variations in the measured absorptions are in essence related to variations in the product of the density and thickness of the sample, so that the method can be employed, in practice, when seeking information concerning variations in density, with the temperature or the time. The technique was used to investigate a number of polymers, e.g., polyethylene terephthalate, polystyrene, polyethylene, 1,4-cis polybutadiene, natural rubber, polyisobutylene, polybutene-1, polypropylene, and certain copolymers of ethylene/propylene and ethylene/butene-1. Finally, data pertaining to phase transitions in organic and inorganic substances are presented. The results are discussed., and compared with those obtained by other methods.

Refractometric Determination of Second-Order Transition Temperatures in Polymers. V. Determination of the Refractive Indexes of Elastomers at Temperatures from 25 to −120° C

1951 ◽  
Vol 24 (3) ◽  
pp. 585-590
Author(s):  
Richard H. Wiley ◽  
G. M. Brauer ◽  
A. R. Bennett
Keyword(s):  
Natural Rubber ◽  
Second Order ◽  
Order Transition ◽  
Transition Temperatures ◽  
Refractometric Method ◽  
Second Order Transition ◽  
Refractometric Determination ◽  
Transition Points

Abstract In previous papers a refractometric method was described for determining second-order transition temperatures of polymers whose transitions occur between 75 and −60° C. In the present study, an Abbé refractometer was insulated and used to determine the refractive indexes of polymers down to − 120° C and the transition points of natural rubber and a number of synthetic rubbers.

Refractometric Determination of Second-Order Transition Temperatures in Polymers. IV. Butadiene-Acrylo-Nitrile Copolymers

1949 ◽  
Vol 22 (2) ◽  
pp. 402-404 ◽  
Author(s):  
Richard H. Wiley ◽  
G. M. Brauer
Keyword(s):  
Low Temperature ◽  
Linear Relation ◽  
Second Order ◽  
Order Transition ◽  
Copolymer Composition ◽  
Transition Temperatures ◽  
Second Order Transition ◽  
Refractometric Determination ◽  
Acrylonitrile Copolymers

Abstract A previous study of the low-temperature properties of a series of vulcanized butadiene-acrylonitrile copolymers indicated an approximately linear relation between composition and brittle temperature. This study provides information relating low-temperature properties to copolymer composition for a series of industrially available butadiene-acrylonitrile copolymers of varying acrylonitrile content. The refractometric technique for determining second-order transition temperatures (Tm) as previously described was used to determine Tm.

NMR · NQR and DTA · DSC Studies of Phase Transitions in Pyridinium Tetrachloropalladate(II) and Pyridinium Tetrachloroplatinate(II)

1998 ◽  
Vol 53 (6-7) ◽  
pp. 419-426 ◽  
Author(s):  
Tetsuo Asaji ◽  
Keizo Horiuchi ◽  
Takehiko Chiba ◽  
Takashige Shimizu ◽  
Ryuichi Ikeda
Keyword(s):  
Phase Transitions ◽  
Low Temperatures ◽  
Structural Phase ◽  
Orientational Order ◽  
Second Order ◽  
Order Transition ◽  
Spin Lattice Relaxation ◽  
Potential Wells ◽  
H Nmr ◽  
Second Order Transition

Abstract From the measurements of DTA • DSC and the temperature dependences of 35Cl NQR frequencies, phase transitions were detected at 150 K, 168 K, and 172 K for (pyH)2 [PtCl4], and at 241 K for (PyH)2 [PdCl4]. In order to elucidate the motional state of the constituent ions in the crystals in connection with the structural phase transitions, the 35Cl NQR and 1H NMR spin-lattice relaxation times and the second moment of the 1H NMR line were measured as functions of temperature. For both compounds, the potential wells for the cationic reorientation are suggested to be highly nonequivalent at low temperatures. Above 168 K, the pyridinium ions in (pyH)2[PtCl4] are expected to reorient between almost equivalent potential wells. As for (pyH)2[PdCl4], it is expected that the orientational order of the cation still remains even above the second order transition at 241 K. A change of the potential curve from two-unequal to three-unequal wells is proposed as a possible mechanism of the second order transition. The activation energies for the cationic motion in the respective model potential are derived for both compounds at high and low temperatures.

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