X-Ray Study of Thermal Expansion and Transition of Crystalline CelluloseTakahashi, Masae; Takenaka, Haruko
doi: 10.1295/polymj.14.675pmid: N/A
For the cellulose crystals I and II, the spacings and intensities of some typical X-ray reflections were measured over a range of temperature from room temperature to 200°C. The spacing vs. temperature curve for each reflection exhibited a distinct break at about 150°C for Cell I and at about 100°C for Cell II. The thermal expansion coefficients estimated from this curve for the (101) reflection of Cell I were 5.1×10−5 K−1 below 150°C and 1.6×10−4 K−1 above 150°C. The intensity vs. temperature curve for each reflection also exhibited a break at the same temperature as that for the break of the corresponding spacing vs. temperature curve. The reason for the appearance of these breaks is not yet clear.
Statistical Thermodynamics of r-Mer Fluids and Their MixturesPanayiotou, C; Vera, J H
doi: 10.1295/polymj.14.681pmid: N/A
A modified fluid-lattice theory of fluids considering a finite quasi-lattice coordination number and a constant lattice site volume for all r-mers is developed. The theory is tested against experimental information on specific volumes, vapor pressures, orthobaric densities and heats of vaporization of pure components. Some common polymers and some typical polymer solvents have been chosen for testing the theory. The theoretical treatment has been extended to mixtures and tested against experimental data on volumes of mixing, heats of mixing, and χ interaction parameters of polymer solutions. Results have been compared with those obtained with a two-parameter new Flory theory and with the three-parameter new Huggins theory. Both for pure components and for mixtures, the effect of introducing a non-random quasi-chemical correction is discussed.
Inter- and Intramolecular Interactions of Polymers as Studied by Fluorescence Spectroscopy. XIV. Emission by Pyrene-N,N-Dimethylaniline Pair in Glassy 2-Methyltetrahydrofuran MatrixTazuke, Shigeo; Yuan, Hui Liang
doi: 10.1295/polymj.14.695pmid: N/A
Emission and absorption spectra of a polyester having pyrene and N,N-dimethylaniline groups (I) were studied in 2-methyltetrahydrofuran (MTHF) between room temperature (r.t.) and 77 K and the results were compared with a series of model compounds (II, III, and IV). The following important results were obtained: i) I emits fluorescence from excited EDA (electron donor acceptro) complex (λmax≍440 nm) in a glassy matrix below ∼90 K while II hardly does so. ii) Exciplex emission by I at r.t. decreases with lowering temperature and the locally excited state of pyrene alone is observed at an intermediate temperature region, iii) EDA emission relative to pyrene emission is intensified by increasing the degree of polymerization (DP) of I whereas the concentration effect is not observed indicating that intrapolymer EDA complexes are formed with possible non-neighboring group participation, iv) The absorption spectrum of I at 77 K is much broader than that of II in support of EDA complex formation by I. v) In accordance with the results of absorption spectroscopy, the excitation spectrum monitored at 440 nm at 77 K is broader than that monitored pyrene emission. This is a good indication that the origin of absorption spectrum broadening is relevant to the EDA emission. Since these findings are very different from emission characteristics of a polymer bound exciplex at r.t., comparative study on EDA and exciplex emission was conducted and the possible factors controlling these emissions are discussed.
Free-Radical Copolymerization I. Reactivity Ratios in Bulk-Copolymerization of p-Chlorostyrene and Methyl AcrylateFukuda, Takeshi; Ma, Yung-Dae; Inagaki, Hiroshi
doi: 10.1295/polymj.14.705pmid: N/A
In order to establish the composition equation for the bulk-copolymerization of p-chlorostyrene (monomer 1) and methyl acrylate (monomer 2) at 40°C, an extraordinarily large number of careful polymerization runs were carried out covering a wide range of feed composition. The samples were analyzed for composition by both potentiometric titration for chlorine and combustion analysis for carbon. The optimum set of terminal-model parameters evaluated by a least-squares curve-fitting procedure are r
1=1.21 and r
2=0.144, quite at variance with the literature values, but conform to the Q–e scheme. However, the chlorine and carbon sets of data consistently indicate failure of the terminal model to accurately represent this system. The penultimate model parameters r
1=0.92, r
1′=2.3, and r
2 (=r
2′)=0.18 represent the system almost perfectly. This indicates the presence of significant penultimate effects on type-1 radicals. The question as to the penultimate effects on type-2 radicals remains to be answered.
Structural Characterization of Cyclic Isoprene TrimerTanaka, Yasuyuki; Sato, Hisaya; Nakafutami, Yasunobu; Iwasaki, Hitoshi; Taketomi, Takanao
doi: 10.1295/polymj.14.713pmid: N/A
A study was made on the isomeric structure of trimethyl-cyclododecatriene (TMCDT) prepared by oligomerization of isoprene with (C5H8)2Mg–AlCl3–TiCl4–CH3SCH3 as a catalyst. The 1H and 13C NMR spectra of this compound showed the presence of one cis and two trans double bonds. The partial ozonolysis of TMCDT followed by the reductive degradation to alcohols gave three products corresponding to a linear trimer and two dimers of isoprene. These products were fractionated by liquid chromatography. 13C NMR measurements showed these partial ozonolysis products to be 5-methyl-cis-5-decene-2,9-diol, 5-methyl-transs-4-nonene-1,8-diol, and 5,8-dimethyl-trans-cis-4,8-tridecadiene-1,12-diol, indicating that one of the trans isoprene units was linked to the other isoprene units in a head-to-head and tail-to-tail fashion. This was also confirmed by an infrared measurement of hydrogenated TMCDT. The TMCDT was concluded to be 1,5,9-trimethyl-cis-trans-trans-cyclododecatriene.
Equations of State for Poly(vinylidene fluoride)Tanaka, Hiroshi; Takayama, Koichi; Okamoto, Toshiyuki; Takemura, Tetuo
doi: 10.1295/polymj.14.719pmid: N/A
Equations of state were determined separately for the crystalline and amorphous parts of Form I and II samples of poly(vinylidene fluoride), assuming a linear relation between the specific volume and the degree of crystallinity. The compressibility data of Form II bulk samples were obtained by dilatometry, and those of the Form I and II crystals were determined by X-ray diffraction at high temperature. Ultrasonic sound velocities of Form I and II crystals were obtained as functions of pressure and temperature, using the logarithmic mixture law for sound velocity. The pressure dependences of the Grüneisen constants γ and interchain specific heats C
inter were derived for Form I arid II crystals at room temperature. Form I crystals had somewhat larger compressibilities than those of Form II throughout the whole range of temperature investigated, and had a larger γ and smaller C
inter at atmospheric pressure, but smaller γ at high pressures above 2000 kg cm−2. The pressure dependences of γ and C
inter were stronger in Form I than in Form II. On the basis of these facts, the difference in behavior of the lattice vibrations of these two crystals under high pressure is discussed.
Partial Volume of Copolymers in Mixed Solvents and Volume Contraction in Bulk-CopolymerizationFukuda, Takeshi; Ma, Yung-Dae; Nagata, Minoru; Inagaki, H
doi: 10.1295/polymj.14.729pmid: N/A
On the basis of a simple and unified phenomenological method for treating the excess volume of mixing in multicomponent systems, formulas were developed for the partial molar volume of a copolymer (or a mixture of two polymers) in a mixture of two solvents and for the volume contraction factor in the bulk-copolymerization of two monomers. The possible dependence of the “net” volume of a copolymer on its primary structure was taken into account. The proposed formulas were partly checked against some experimental data, and found satisfactory. The previously proposed formulas for the copolymerization contraction factor seem to be less generally applicable.
Rheology of Styrene–Butadiene Diblock Copolymers Dissolved in Selective Solvent: Dependence on Molecular DimensionWatanabe, Hiroshi; Kotaka, Tadao
doi: 10.1295/polymj.14.739pmid: N/A
The rheology of solutions of a series of styrene–butadiene diblock copolymers dissolved in a highly selective solvent, n-tetradecane, was examined in relation to the molecular dimension of the block copolymers. Micelles with precipitated S cores and dissolved B cilia are formed in the solution. Above a certain concentration and below a certain temperature, micelles in the solution are spontaneously arranged to form a regular three-dimensional array referred to as a macrolattice. Solutions having macrolattice structures exhibit nonlinear viscoelastoplastic flow, and those having no macrolattices exhibit linear viscoelastic flow. The critical concentration, at which transitions in rheology and morphology occur, may be predicted from the structural characteristics of the micelles, i.e., their size and number of molecules making up a micelle. The relationship of dynamic moduli and the molecular dimensions was examined in detail. The shorter the length of dissolved B blocks, the larger the storage modulus and the smaller the loss modulus. Two mechanisms, being the delayed relaxational motions of the dissolved B blocks and deformation of the macrolattice itself, seem responsible for the stress in the solution. The mechanism of the lattice disordering caused by heat is also discussed. A diffuse interphase between the S core and B cilia seems to play a key role in the lattice disordering.