Tadaya Kato

Melting temperatures of thermally reversible gels IV. Methyl cellulose-water gels

SummaryThe gel/sol transition temperatures (Tmg) were measured by cooling of thermally reversible methyl cellulose (MC)-water gels using the ten MC samples. A linear relationship between 1/Tgm and the logarithm ofv2x was found for each MC gel, wherev2 is the volume fraction of MC andx the degree of polymerization. The X-ray diffraction patterns of both MC films and gels revealed that the network junction points of the MC gels are crystalline and consist of trimethyl glucose units. The heat of fusion of trimethyl cellulose was estimated as 2.6 × 103 J/mol, and entropy of dilution parameter = −1.6 andΘ = 320 K were also evaluated. Using these values, the gel/sol transition temperature was analysed according to our previous theory. It is concluded that the network junction points of MC gels are between 4 and 8 units long and also that the length is in good agreement with the sequence length estimated from the methoxy content of MC.ZusammenfassungDie Umwandlungstemperaturen (Tgm) Gel/Sol von zehn Methylzelluloseproben (MC) wurden an dem Abkühlungsverhalten von reversiblen Methylzellulose-Wasser-Gelen untersucht. Ein linearer Zusammenhang zwischen 1/T/gm und den logarithmischenv2x-Werten wurde für jedes MC-Gel gefunden, worinv2 die Volumenfraktion von MC undx den Polymerisationsgrad bedeuten. Die Röntgendiagramme von beiden, MC-Film und MC-Gel, weisen darauf hin, daß die Verzweigungspunkte vom MC-Gel Kristallite sind und diese aus Trimethylglukosegrundbausteinen aufgebaut werden. Die Schmelzwärme der Trimethylglukose wurde zu 2.6 × 103 J/mol geschätzt, und der Wechselwirkungsparameter χ sowie die Theta-Temperatur wurden alsχ = −1.6 undΘ = 320 K berechnet. Nimmt man diese Werte an, so kann man die Gel/Sol-Übergangstemperaturen nach unserer früheren Theorie bestimmen. Daraus läßt sich folgern, daß die Verzweigungspunkte von MC-Gel zwischen 4 und 8 Bausteinen lang sind und daß dies auch mit der bezüglichen Sequenzlänge, die aus dem Methoxygehalt abgeschätzt werden kann, übereinstimmt.

Molecular characterization of sodium poly(acrylate) by an aqueous g.p.c./LS method

Abstract The molecular characterization of a commercial sample of sodium poly(acrylate) (NaPA) has been carried out by a g.p.c./LS method in 0.3 N NaCl at 25°C. The sample is fractionated into eight fractions. The agreements between the weight-average molecular weights of the NaPA fractions determined by light scattering and those measured directly by the g.p.c./LS method are excellent. Universal calibration is established for both the standard poly(ethylene oxide) and the NaPA fractions. The degree of branching for the fractions with high molecular weights are estimated using the experimental results obtained by the g.p.c./LS method.

Comparison of poly(ethylene oxide), pullulan and dextran as polymer standards in aqueous gel chromatography

Abstract Aqueous gel chromatography for poly(ethylene oxide), pullulan and dextran was carried out in 0.1 M aqueous sodium chloride solution at 25°C using a cross-linked hydrophilic vinyl polymer gel. From the results obtained, log M w vs . V r,w calibration curves for both poly(ethylene oxide) and pullulan were linear over a wide molecular weight range, where M w , denotes the weight-average molecular weight of the sample and V r,w the retention volume at the centre of mass of the chromatogram peak. However, the corresponding calibration curve for dextran was non-linear. Evidence in support of the universal calibration procedure was obtained for the three polymers since a single straight line could be drawn through all data points. It is concluded that poly(ethylene oxide) provides the best standards, while pullulan is also important because of the analogy of its chemical structure with those of other linear polysaccharides.

Non-destructive determination of wood constituents by fourier transform Raman spectroscopy

Abstract The feasibility of using FT-Raman spectroscopy for rapid determination of various wood constituents non-destructively was examined using five Eucalyptus species, including samples of various ages and colors of samples, which are of importance as a plantation source. Wood constituents which relate to pulp properties (holocellulose, α -cellulose, hemicellulose, lignin, extractives, alkali-extractives, total-extractives, and extractives-free (EF) wood constituents for holocellulose, α -cellulose, hemicellulose and lignin) were measured. The application of 2nd derivatives transformation of Raman spectroscopic data revealed highly significant correlations between wet chemical and Raman predicted values for all traits except EF-hemicellulose, with standard error of prediction (SEP) < 0.8 points in the calibration (for known samples) and SEP < 3.4 points in the prediction (for unknown samples), respectively. Consequently, this non-destructive method has proved its validity for analyzing various Eucalypt...

Non-destructive determination of lignin syringyl/guaiacyl monomeric composition in native wood by Fourier transform Raman spectroscopy

Abstract The feasibility of using FT-Raman spectroscopy for rapid non-destructive determination of lignin syringyl/guaiacyl (S/G) monomeric composition was examined using Eucalyptus camaldulensis and E. globulus, including samples of various ages and colors, which are of importance as a plantation source. The application of 2nd derivatives transformation of Raman spectroscopic data revealed highly significant correlations between wet chemical and Raman predicted values with correlation coefficient (r) = 0.998 and standard error of prediction (SEP) < 0.07 points in the calibration (for known samples), and r = 0.935 and SEP < 0.32 points in the prediction (for unknown samples), respectively. Consequently, this nondestructive method has proved its validity for analyzing Eucalyptus native wood meal samples, regardless of their age and color to determine lignin S/G monomeric composition. Using FT-Raman spectroscopy, elite tree selection based on quality aspects for pulp and paper production can be performed.

Phase diagrams of polymer dispersed liquid crystals

A simple model is introduced to describe liquid crystal transitions and phase separations in binary mixtures of a flexible polymer and a liquid crystal. By combining the McMillan theory for the smectic A phase of liquid crystals with the Flory–Huggins theory for the isotropic mixing of two components, we examine binodal and spinodal lines on the temperature-concentration plane. We predict the appearance of phase separations such as the smectic A-nematic, smectic A-isotropic, and smectic A-nematic-isotropic phase separations. We also find a tricritical point caused by the interference between a second-order liquid crystal transition and a phase separation.

Stereoregular emulsion polymerization of butadiene

The stereoregular emulsion polymerization of butadiene was performed with a cobalt catalyst (J. N. Henderson et al., U.S. Patent 4,429,085, 1984; H. Ono et al., Jpn. Open Patent 85-147410, 1985; H. Ono et al., Jpn. Open Patent 85-161408, 1985; H. Ono et al., Jpn. Open Patent 85-14711, 1985; H. Ono et al., Jpn. Open Patent 86-69818, 1986; H. Ono et al., Jpn. Open Patent 86-23610, 1986). This is the first report of a successful highly stereoregular emulsion polymerization with water as the solvent (H. Ono et al., Jpn. Open Patent 85-14711, 1985; H. Ono et al., Jpn. Open Patent 86-69818, 1986; H. Ono et al., Jpn. Open Patent 86-23610, 1986); water is usually recognized as a strong inhibitor of transition-metal polymerization. By analyzing the addition order effect of the ingredients, we show that the reduction of cobalt in the presence of butadiene is necessary for the polymerization. Radical-polymerization inhibitors such as phenols did not terminate the polymerization reaction, but sulfur did. Moreover, the valence of the reduced cobalt butadiene complex catalyst is considered zero. The zero-valent cobalt is classified as a soft acceptor, butadiene is a soft donor, and water is a hard acceptor. In this article, we discuss the reason butadiene could be polymerized stereoregularly by an emulsion system.

Volume phase transitions of nematic gels under an external field

The effect of external (magnetic or electric) fields on the swelling of nematic gels dissolved in an isotropic solvent are discussed. We calculate the swelling ratio of the gel, orientational order parameter, and phase diagrams on a temperature–swelling ratio plane under an external field. For a weak external field, we find a first-order volume phase transition between two nematic gels with different orientational ordering. Upon increasing the strength of an external field, a critical point appears on the phase diagram. We also discuss the swelling of nematic gels as a function of the strength of an external field for various temperatures.

Non-Destructive Determination of Hemicellulosic Neutral Sugar Composition in Native Wood by Fourier Transform Raman Spectroscopy

Abstract The feasibility of using FT-Raman spectroscopy for rapid non-destructive determination of hemicellulosic neutral sugar composition, important factors for pulp properties, in native wood was examined using two Eucalyptus species, including samples of various ages and colors, which are important sources of plantation pulpwood. The sugars, glucose, xylose, galactose, rhamnose, arabinose and mannose were utilized. The application of 2nd derivatives transformation of Raman spectroscopic data revealed highly significant correlations between wet chemical and Raman predicted values in the calibration (known samples) with correlation coefficients > 0.99, and in the prediction (unknown samples) with correlation coefficients > 0.80 with the exception of rhamnose and mannose. Consequently, this non-destructive method will be valid for analyzing Eucalyptus native wood meal samples, regardless of their age and color to determine hemicellulosic neutral sugar composition except rhamnose and mannose. Elite tree s...

Synthesis and hydrolysis resistance of polyurethane derived from 2,4-diethyl-1,5-pentanediol

A new polyester polyol was synthesized using 2,4-diethyl-1,5-pentanediol, which has two ethyl groups as side chains. A new polyurethane was synthesized using this polyester polyol. The hydrolysis resistance and the mechanical properties of this polyurethane were investigated. Several kinds of polyurethanes using polyester polyol derived from common or so-called hydrolysis-resistant diol were synthesized at the same time to compare the hydrolysis resistance of these polyurethanes with that of the new polyurethane thus synthesized. The polyurethane using polyester polyol derived from 2,4-diethyl-1,5-pentanediol showed the following characteristics: (1) Excellent hydrolysis resistance; (2) The most flexible and the lowest hardness among synthesized polyurethanes.