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Effect of pressure on the cohesion of polypropylene
Abstracts
321
INVESTIGATION INTO THE TEMPERATURE-FREQUENCY ANGLE
OF DIELECTRIC
LOSSES OF MIXED
RELATIONSHIPS
OF THE
POLYESTERS
G. P. Mikhailov and M. P. Eidelnant, Vysokomol. soedin. 2: No. 2, 295-302, 1960. THE temperature-frequency relations of the angle of dielectric losses for a number of mixed polyesters of a.romatic and aliphatic acids have been investigated. Two regions of dipole-radical losses corresponding to the two acids and one region of dipole-elastic loftses have been found for all the polyesters. The temperature of maximum @ of the dipole-ela&ic losses is determined by the concentration of the polyester component. The capacity for crystallization of the mixed polyesters of which one component. does uot crSystallize increases with increase in concentration of the crystallizing component in the polyester. When the crystallizing component cantains more aromatic nuclei than the noncrystallizing component an increase in the degree of crystallinity may lead to a fall iu the temperature of maximum trJd of the dipole-elastic losses. EFFECT
OF PRESSURE
Yu. V. Ovchinnikov,
ON THE COHESION OF POLYPROPYLENE
K. S. Minsker and L. A. Igonin,
Vysokomol.
soedin. 2:
1\To.2, 306-309, 1960. THE conditions for the formation of transparent specimens on the compression molding of polypropylene powders oven a large range of temperatures and pressures have been investigated, I Whatever the pressure no intergrowth of the polymer particles with the disappearance of physical boundaries between them takes place at, temperatures below the melting point of polypropylene (T,n = 169°C). The formation of transparent articles is possible in the temperature and pressure regions bounded by the upper branch of the pressure-temperature curve. The region is above the polypropylene melting temperature. The application of high pressures raises the melting temperature. Articles molded at 200°C and pressures above the upper limit (above the limit of formation of opaque materials) posees inferior physico-mechanical properties as compared with those formed at pressures below this limit. ON THE EXPRESSION FOR THE RESILIENCE IN THE NON-EQUILIBRIUM STATE
L. S. Priss, Vysokomol.
POTENTIAL
OF STRAINED
RUBBER
soedin. 2: No. 2, 313, 1960.
THE roasons are given for the deviation between the expressions for the resilience potential of rubber in the non-equilibrium state obtained by the author and by Mooney. A method for the experimental testing of one of bhe fundamental principles underlying the theor) has been proposed. This consists in measuring the change in the resilience potential with t,ime in’ the initial period aft.er deformation of the rubber. CYCLIC COPOLYMERIZATION
S. G. Matsoyan,
OF D1VINYLACETA.L
M. N. Avet,yan
AND VINYL MONOMERS
and M. G. Poskanyan,
Vysokomol.
so&in.
2:
n’o. 2, 14, 1960. THE possibility of cyclic copolymerization has been st.udied in t,he cases of divinylbutyral with styrene and vinyl acetate. The copolymers formed are soluble in benzene, chloroform and acetone and do not contain double bonds.
321
INVESTIGATION INTO THE TEMPERATURE-FREQUENCY ANGLE
OF DIELECTRIC
LOSSES OF MIXED
RELATIONSHIPS
OF THE
POLYESTERS
G. P. Mikhailov and M. P. Eidelnant, Vysokomol. soedin. 2: No. 2, 295-302, 1960. THE temperature-frequency relations of the angle of dielectric losses for a number of mixed polyesters of a.romatic and aliphatic acids have been investigated. Two regions of dipole-radical losses corresponding to the two acids and one region of dipole-elastic loftses have been found for all the polyesters. The temperature of maximum @ of the dipole-ela&ic losses is determined by the concentration of the polyester component. The capacity for crystallization of the mixed polyesters of which one component. does uot crSystallize increases with increase in concentration of the crystallizing component in the polyester. When the crystallizing component cantains more aromatic nuclei than the noncrystallizing component an increase in the degree of crystallinity may lead to a fall iu the temperature of maximum trJd of the dipole-elastic losses. EFFECT
OF PRESSURE
Yu. V. Ovchinnikov,
ON THE COHESION OF POLYPROPYLENE
K. S. Minsker and L. A. Igonin,
Vysokomol.
soedin. 2:
1\To.2, 306-309, 1960. THE conditions for the formation of transparent specimens on the compression molding of polypropylene powders oven a large range of temperatures and pressures have been investigated, I Whatever the pressure no intergrowth of the polymer particles with the disappearance of physical boundaries between them takes place at, temperatures below the melting point of polypropylene (T,n = 169°C). The formation of transparent articles is possible in the temperature and pressure regions bounded by the upper branch of the pressure-temperature curve. The region is above the polypropylene melting temperature. The application of high pressures raises the melting temperature. Articles molded at 200°C and pressures above the upper limit (above the limit of formation of opaque materials) posees inferior physico-mechanical properties as compared with those formed at pressures below this limit. ON THE EXPRESSION FOR THE RESILIENCE IN THE NON-EQUILIBRIUM STATE
L. S. Priss, Vysokomol.
POTENTIAL
OF STRAINED
RUBBER
soedin. 2: No. 2, 313, 1960.
THE roasons are given for the deviation between the expressions for the resilience potential of rubber in the non-equilibrium state obtained by the author and by Mooney. A method for the experimental testing of one of bhe fundamental principles underlying the theor) has been proposed. This consists in measuring the change in the resilience potential with t,ime in’ the initial period aft.er deformation of the rubber. CYCLIC COPOLYMERIZATION
S. G. Matsoyan,
OF D1VINYLACETA.L
M. N. Avet,yan
AND VINYL MONOMERS
and M. G. Poskanyan,
Vysokomol.
so&in.
2:
n’o. 2, 14, 1960. THE possibility of cyclic copolymerization has been st.udied in t,he cases of divinylbutyral with styrene and vinyl acetate. The copolymers formed are soluble in benzene, chloroform and acetone and do not contain double bonds.