Dielectric Properties of Unsaturated Polyester Resins II. The Effect of the Content of Cross-linker Styrene

• Published in: Kobunshi Kagaku Vol. 13; no. 133; pp. 185 - 192
• Main Authors: Goto, Kenzo, Nakajima, Tatsuji
• Format: Journal Article
• Language: Japanese
• Published: The Society of Polymer Science, Japan 25.05.1956
• ISSN: 0023-2556; 1884-8079
• DOI: 10.1295/koron1944.13.133_185

Following the previous paper, the similar measurements were carried out in regard to the polyester resins containing various quantities of cross-linker styrene. Until the monomer content reached to the quantity equivalent to the unsaturation degree of the polyester, the peak of dielectric loss ε″ became lower and shifted to the higher temperature side, as the increases of cross-linker content ;when the monomer content became somewhat excess, the distribution of the relaxation time grows broader, the peak of the dielectric loss becomes flatter and ε′or ε″ has rather greater value, excepting in the case of higher and extremely low temperature range ;but when the monomer content was increased still more, the value of ε′ or ε″decreases gradually by the dilution effect.The same tendency was recognized also in the case of d.c. conductivity ;namely, the sample with the styrene equivalent to the unsaturation degree of the polyester shows the minimum value.For this reason, it was suggested that styrene bridge consisting of more than one molecule, which is cross-linking the polyester chains, hinders the intermolecular bonding between ester groups.But the above tendency is varied by the structure of the saturated acid contained;and for instance, in the case of the polyester modified with succinic acid, dielectric loss decreased linearly with increase of styrene content.