Low-Temperature Properties of Plasticized Butadiene-Styrene Copolymers

1955 ◽  
Vol 28 (2) ◽  
pp. 557-569 ◽  
Author(s):  
D. A. Henderson ◽  
L. A. McLeod
Keyword(s):  
Transition Temperature ◽  
Low Temperature ◽  
Second Order ◽  
Order Transition ◽  
Styrene Copolymers ◽  
Second Order Transition ◽  
Dibutyl Sebacate ◽  
Special Case ◽  
Measured Transition ◽  
Butadiene Styrene

Abstract The second-order transition temperatures of plasticized butadiene-styrene copolymers have been measured by dilatometric techniques. In a series of ester plasticizers, the ability of a given plasticizer to depress the second-order transition temperature of the polymer is related to the swelling effect of the plasticizer on the polymer. The special case of a crystallizing plasticizer (dibutyl sebacate) has been discussed. Common petroleum plasticizers do not appear to behave in a similar manner. The change of coefficient of expansion of the ester-plasticized copolymers is related to the measured transition temperature of the blend.

Ideal Copolymers and the Second-Order Transitions of Synthetic Rubbers. I. Noncrystalline Copolymers

1953 ◽  
Vol 26 (2) ◽  
pp. 323-335 ◽  
Author(s):  
Manfred Gordon ◽  
James S. Taylor
Keyword(s):  
Thermal Expansion ◽  
Transition Temperature ◽  
Small Molecules ◽  
Second Order ◽  
Order Transition ◽  
Kinetic Measurements ◽  
Practical Applications ◽  
Second Order Transition ◽  
Binary Copolymers ◽  
General Reduction

Abstract Theoretical and practical evidence is put forward to show that copolymers can be treated like solutions of small molecules in the interpretation of packing phenomena, and that ideal volume-additivity of the repeating units in copolymers is frequently realized. On this basis equations are derived for predicting θ, the second-order transition temperature, of binary copolymers from the two second-order transition temperatures of the pure polymers and their coefficients of expansion in the glassy and rubbery states. Previous mechanistic theories of the second-order transition temperature of such copolymers are thus superseded by a general reduction of the problem to the mechanism of thermal expansion. Practical applications to the choice of monomers in producing synthetic rubbers are outlined, and attention is drawn to the importance of second-order transitions in kinetic measurements on the reactions of polymers.

ESCAPE RATE TRANSITIONS IN THE Fe8 MOLECULAR MAGNET WITH FOURTH-ORDER TRANSVERSE ANISOTROPY

2004 ◽  
Vol 18 (07n08) ◽  
pp. 291-300
Author(s):  
CHANG-SOO PARK
Keyword(s):  
Transition Temperature ◽  
Fourth Order ◽  
Second Order ◽  
Order Transition ◽  
Escape Rate ◽  
Molecular Magnet ◽  
Transverse Anisotropy ◽  
Second Order Transition ◽  
First Order Transition ◽  
Transition Type

We study escape rate transitions in the Fe 8 molecular magnet with fourth-order transverse anisotropy in the presence of an external field perpendicular to the easy axis. Direct numerical diagonalization has been employed to investigate the transition type and the transition temperature T0. We find that the first-order transition as well as the second-order transition can exist when the field is applied along the hard axis, while only the second-order transition appears for the field along the medium axis. It is also observed that the transition temperature is increased due to fourth-order transverse anisotropy.

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