Showing papers by "Grzegorz Czechowski published in 1990"

Dielectric Properties of Morpholine and Some of Its Derivatives in the Pure Liquid State and in Mixtures with Benzene or Water

Abstract: The following substances are regarded as pure liquids and in benzene mixtures: morpholine, 2,6-dimethylmorpholine, N-methyl-(MeMo), N-ethyl-, N-cyano-(CyMo) and N-formylmorpholine (FoMo). Their dielectric constant and complex permittivity over the whole dispersion range (up to 72 GHz) are determined at 20°C. By comparing dipole moments in dilute benzene solution and in the pure state and by considering the relaxation times, probable molecular conformations and the association behaviour are discussed. Chair forms are most likely, but some parameters point to enhanced planarity of CyMo and FoMo. Self-association (probably dimerization) occurs if there is no N-substituent. Additional relaxation measurements on aqueous mixtures of MeMo and FoMo reveal a considerable tendency towards hetero-association.

Dielectric Studies of the Structure in Some Homologous Series of Esters and Their Mixtures

Abstract: The results of electric permittivity and conductivity measurements for mesogens from the CBnAB (n = 5−8) homologous series and for the mixtures of CB7AB with 10XPCHB (X = F or COCH3), are presented.