DIPOLE-MOMENTS OF ISOTACTIC AND ATACTIC POLY(PROPYLENE OXIDE) SAMPLES

1991-01-01
KUCUKYAVUZ, Z
ALYURUK, K
AHMAD, AM
Dipole moments of poly(propylene oxide) (PPO) samples with different tacticities were determined from dielectric constant and refractive index increment measurements, which were performed on dilute toluene and isooctane solutions. In contrast to previous reports, both refractive index increments and the dipole moment ratios showed a marked dependence on the tacticities of the samples. The dipole moment ratios of isotactic samples were greater than unity and decreased with increasing sequence concentrations of structural irregularities. The temperature coefficients in toluene were negative for both isotactic and atactic samples. No effect of excluded volume was observed.

Suggestions

DIPOLE-MOMENTS OF COPOLYMERS IN RELATION TO THE DISTRIBUTION OF POLAR MONOMER UNIT SEQUENCES
KUCUKYAVUZ, Z; BAYSAL, BM (Elsevier BV, 1991-01-01)
A method for evaluating the dipole moments of copolymers in relation to the distribution of polar unit sequences is proposed. Experimental data on the synthesis and dipole moments of styrene-p-chlorostyrene and styrene-p-methoxystyrene copolymers were used to calculate the effective dipole moment of a polar unit in a copolymer. For this purpose, we assumed the following effective moment values for the corresponding polar unit sequences along the copolymer chains: when both of the nearest neighbours are pola...
MONOMER REACTIVITY RATIOS OF STYRENE-4-VINYLPYRIDINE COPOLYMERS AT LOW AND HIGH CONVERSIONS
YILMAZ, E; KUCUKYAVUZ, Z (Elsevier BV, 1993-01-01)
Monomer reactivity ratios in free-radical copolymerization of styrene and 4-vinylpyridine monomers at 80-degrees-C in toluene solution under reduced pressure were determined for low and high conversions. Finemann-Ross, Kelen-Tudos, extended Kelen-Tudos and Mayo-Lewis methods were used for this purpose. The most reliable method was found to be the extended Kelen-Tudos method. By the use of this method, for conversions below 20%, monomer reactivity values of 0.700 +/- 0.005 and 0.335 +/- 0.001 were calculated...
EFFECT OF ION ASSOCIATION ON THE PROPERTIES OF IONOMERS OBTAINED FROM METHYL-METHACRYLATE METHACRYLIC-ACID COPOLYMER
KOCAK, HI; ARAS, L (Elsevier BV, 1990-07-01)
The solution behaviour of Na, Ba, Zn and Al ionomers of methyl methacrylate-methacrylic acid copolymer (P(MMA-MAA)) with different ion contents has been studied by viscosity and dipole moment measurements. Two solvents with different character are chosen for viscosity measurements: dioxane (ε = 2.22) and acetone (ε = 20.7). The expected polyelectrolyte behaviour of the ionomers in acetone is reflected by the viscometric measurements. Mean squared dipole moment 〈μ2〉 values are calculated over a temperature r...
Electrochemical polymerization and characterization of polyether-substituted aniline derivatives
Tirkeş, Süha; Oenal, Ahmet M. (Wiley, 2007-08-01)
New compounds consisting of aniline units linked by polyether bridges have been synthesized and their electrochemical polymerization was performed via constant potential electrolysis and cyclic voltammetry in an aqueous solution containing 3.0 moI L-1 H2SO4. Chemical polymerization was carried out using (NH4)(2)S2O8 as oxidizing agent. It was found that both methods gave the same polymer product without any cleavage of the polyether bridge between aniline rings. The polymers were characterized using the Fou...
Comparison of crystallinities of high density polyethylene determined by different techniques
Akovali, G; Atalay, A (Elsevier BV, 1997-01-01)
The differences in the crystallinities of HDPE samples conditioned by three different procedures with different cooling rates were followed by use of FTIR, DSC and X-ray scattering techniques. From FTIR, relative values of crystallinities are obtained and if absolute values obtained from DSC and X-ray scattering are compared, the latter yielded higher values. All three groups of results showed the expected trend of increase of crystallinities with decrease of rate of cooling. (C) 1997 Elsevier Science Ltd.
Citation Formats
Z. KUCUKYAVUZ, K. ALYURUK, and A. AHMAD, “DIPOLE-MOMENTS OF ISOTACTIC AND ATACTIC POLY(PROPYLENE OXIDE) SAMPLES,” POLYMER, pp. 564–568, 1991, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/67276.