Polymer Journal

Gmachowski, Lech

doi: 10.1295/polymj.18.783pmid: N/A

It is shown that the concentration dependence of the coils-solvent permeability coefficient, experimentally determined over a wide range, may be well described by corrected Brinkman’s model for the fluid flow relative to a swarm of permeable spheres of uniform permeability. A method of checking model reliability is developed. A new method of polymer molecular weight determination is elaborated on the basis of this model. According to this method, molecular weight may be calculated from the function describing concentration dependence of permeability coefficient in a semidilute regime along with a permeability coefficient value in dilute solution.

Gmachowski, Lech

doi: 10.1295/polymj.18.791pmid: N/A

A new relative method of polymer weight determination is developed on the basis of the previously [Polym. J., 18, 783 (1986)] elaborated permeable sphere model. According to this method, the molecular weight of a given polymer may be determined by comparison of its sedimentation coefficient measured at a concentration in the dilute regime with the sedimentation coefficient of the same polymer of known molecular weight in the same solvent. The comparison of sedimentation coefficients must be performed at concentrations corresponding to the same values of the packing fraction of coils. The new method is verified for sedimentation coefficients measured for both a polymer–solvent system at the theta temperature and for a polymer–good solvent system.

Eskin, V E; Baranovskaya, I A; Khudaiberdiev, U S

doi: 10.1295/polymj.18.795pmid: N/A

Light scattering was investigated for polystyrene over a wide molecular weight range in solvents of various thermodynamic strength in the concentration range lower and higher than (100/M) In all cases, the slope of the plots cK/R θ=f(c) at c<100/M was close to horizontal. The concentration c 0 in the range in which the slope of the plot cK/R θ=f(c) passes from the quasi-horizontal to the “usual” vertical slope, is determined only by the molecular weight of the polymer and is virtually independent of the solvent. The excluded volume b and energy of attraction a of macromolecules are determined by using the two-parameter Van der Waals equation. The b 0/V M ratio of the molar values of the excluded volume and the volume proper of macromolecules allows conclusions to be drawn about the degree of interpenetration of the macromolecules and its dependence on the molecular weight and the strength of the solvent. A relationship is established between the swelling coefficient αη of coils and the density ρ of segments in center of the zone of interpenetration of two macromolecules.

Pavlov, A S; Khalatur, P G; Eskin, V E

doi: 10.1295/polymj.18.803pmid: N/A

Computer simulation of dilute solutions of polymer chains has been carried out in the concentration range lower than the critical concentration of coil overlapping. For solvents of various thermodynamic strengths the intermolecular interaction of polymer coils was investigated. The concentration dependence of osmotic pressure π=π(c) was calculated. It was shown that near the θ-point the π(c) curves can be non-monotonic even at very low concentrations as a result of multiparticle interactions. The results obtained make it possible to interpret some anomalies observed in the experimental study of light scattering and osmotic pressure of extremely dilute polymer solutions.

Watanabe, Masayoshi; Nagano, Satoshi; Sanui, Kohei; Ogata, Naoya

doi: 10.1295/polymj.18.809pmid: N/A

The structure-conductivity relationships were investigated on the network polymers from poly(ethylene oxide)(PEO) containing lithium perchlorate (LiClO4), in contrast to the polymer complex formed by linear PEO and LiClO4. The crosslinked structure caused a considerable decrease in the degree of the crystallinity of the resulting PEO–LiClO4 complexes, which contributed to high ionic conductivity. Li+ ions were demonstrated as mobile species in these polymer complexes, while ClO4 − ions contributed somewhat to ionic conductivity. The high ionic conductivity of the order of 10−5 Scm1 at 30°C was attained by a crosslinked PEO–LiClO4 complex of [LiClO4]/[EO unit] =0.02.

Kamide, Kenji; Yamazaki, Hitoshi; Miyazaki, Yukio

doi: 10.1295/polymj.18.819pmid: N/A

Polyacrylonitrile (referred to as γ-PAN) was prepared by γ-ray irradiation on an acrylonitrile–urea canal complex at −78°C. The pentad tacticity was evaluated from 13C NMR spectra according to a method proposed by Kamide et al. The content of a mmmm sequence (m; meso) for γ-PAN was 0.37±0.02 over a wide range of molecular weight, which was about 4.4 times larger than that for PAN, prepared by conventional redox polymerization (R-PAN). Light scattering and solution viscosity were measured in dimethyl sulfoxide (DMSO), 57—67 wt% aq nitric acid at 25°C. By extrapolation of the second virial coefficient A 2 to zero 56.5 wt% aq nitric acid was expected to be a Flory theta solvent at 25°C. Mark–Houwink–Sakurada equations and empirical relations between the radius of gyration ‹S 2›z 1/2 and Mw were determined in various solvents. The unperturbed chain dimension A was determined by four methods. In DMSO γ-PAN has larger A than R-PAN. The conformation parameter σ was 2.6—2.8 for γ-PAN, which is some 35% larger than the expected value when simple steric hindrance due to the side chain group is considered. Unexpectedly larger conformation parameters σ for γ- and R-PAN were interpreted by considering the rigidity of the chain due to intra-interactions between neighbouring CN groups in meso-sequence.

Itoh, Koichi; Oya, Masanao

doi: 10.1295/polymj.18.837pmid: N/A

Raman spectra were measured for copolymers of L-alanine and glycine and those of L-alanine and L-phenylalanine. The L-alanine-glycine copolypeptides with a glycine residue content of 3—21 mol% take the α-helical conformation. On incorporation of the glycine residue at more than 30%, the backbone structure changes partly from the α-helix to the β-form. The L-alanine–L-phenylalanine copolypeptides with the L-phenylalanine content of 12—92% take the α-helical structure. The following Raman bands reflect the α-helix or the β-form structure of the component amino acid residues; the bands near 1308, 1108, 530 and 378 cm−1 are characteristic of the L-alanine residue with the α-helical structure, the band near 1094 cm−1 of the L-alanine resdue with the β-form, the band in the 470—480 cm−1 region of the L-phenylalanine residue with the α-helix, and the band near 490 cm−1 of the L-phenylalanine with the β-form.

Kowsaka, Keisuke; Okajima, Kunihiko; Kamide, Kenji

doi: 10.1295/polymj.18.843pmid: N/A

An attempt was made to determine an unsolved problem in peak assignment of carbonyl carbon region in 13C NMR spectra for cellulose acetate. For this purpose, Kamide and Okajima’s method for determination of the distribution of acetyl group among three hydroxyl groups in a glucopyranose unit was reexamined carefully using a 200 MHz FT-NMR spectrometer, adequate and the most reasonable assignment at present was made on the carbonyl carbon peaks in NMR spectra, applying a low-power selective decoupling method to acetyl methyl proton located at specific carbon position. All three NMR peaks in the carbonyl carbon region were assigned to be attributed to the acetyl groups located at C6, C3, and C2 positions, from the low magnetic field side. The previous Kamide and Okajima’s assignment on C3 and C2 peaks was found to be erroneoulsy made by neglecting an overlapping of the three peaks due to low resolving power in the 1H and 13C NMR spectrometer used by them. The new and complete assignments were in good agreement with those by Miyamoto et al. The method of Miyamoto et al. was examined in detail in the light of the validity of the assignment of carbonyl carbon peaks for not fully substituted cellulose acetate.

Tsubokawa, Norio; Ohshima, Shingo; Sone, Yasuo; Endo, Takeshi

doi: 10.1295/polymj.18.851pmid: N/A

The crosslinking reaction of polyfunctional spiro ortho esters (SOE) i.e., polymers (resins) that bear SOE structure, by carbon black was investigated. The copolymers of 2-methylene-1,4,6-trioxaspiro[4.6]undecane with vinyl monomers were crosslinked in solution upon heating (150°C) together with carbon black to give gels. Furthermore, carbon black was found to be able to cure the SOE resins, which are prepared from epoxy resins and ε-caprolactone, at 120—180°C in bulk. The curing ability of carbon black was enhanced with an increase in the content of carboxyl and phenolic hydroxyl groups on carbon black. By the neutralization of carboxyl group on carbon black, the curing ability of the carbon black decreased remarkably. Carbon black lost the curing ability upon the blocking of both carboxyl and phenolic hydroxyl group by the treatment with diazomethane. Based on these results, it was concluded that both carboxyl and phenolic hydroxyl groups on carbon black play an important role in the curing of polyfunctional SOE resins.

Kurotu, Takuzo

doi: 10.1295/polymj.18.859pmid: N/A

Nuclear magnetic resonance transversal relaxation time (T 2) was measured as a function of polymerization time for methyl methacrylate at various temperatures. Three kinds of relaxation times, T 2l(long), T 2m(intermediate), and T 2s(short) are observed as the polymerization proceeds. T 2l decreases drastically at a certain reaction time, while T 2s changes only slightly throughout the process. The fraction of the T 21 component decreases abruptly when T 2l decreases, while that of the T 2s component increases. The former reflects the decrease in monomer concentration, whereas the latter corresponds to the entanglement of polymer chains to form network structure. The relationship between the fraction of T 2s component and the polymer yield was found to be linear, which gives useful information on this polymerization process in terms of mobility.