Hirokatsu Masuoka

Solubilities and Diffusion Coefficients of Carbon Dioxide and Nitrogen in Polypropylene, High-Density Polyethylene and Polystyrene under High Pressures and Temperatures

Abstract Solubilities of carbon dioxide and nitrogen in molten polypropylene (PP) and high-density polyethylene (HDPE) were measured at temperatures 433.2, 453.2, and 473.2 K and pressures up to 17 MPa. The solubilities increased almost linearly with pressure. While the solubilities of carbon dioxide decreased with increasing temperature, those of nitrogen increased in the temperature range examined. The solubility of nitrogen in glassy polystyrene (PS) was measured at 313.2, 333.2, and 353.2 K and pressures up to 17 MPa. Temperature dependence on the solubility in this system was distinctive, where minimal solubility of 310 cm3(STP)/(kg MPa) was observed around 350 K, by taking into account of our previous data above 373.2 K. Henrys constants, KP, and their temperature dependence were determined from the experimental data. A linear relationship between ln(1/KP) and (TC/T)2 was obtained for each system. Diffusion coefficients of gases in molten polymers were determined for the nitrogen+PP, nitrogen+HDPE, and carbon dioxide+HDPE systems at 453.2 K. The diffusion coefficients showed weak concentration dependence and had an order of magnitude of 10−9 m2/s.

Solubilities and diffusion coefficients of carbon dioxide in poly(vinyl acetate) and polystyrene

Abstract Solubilities of carbon dioxide in poly(vinyl acetate) (PVAc) were measured at temperatures from 313.15 to 373.15 K and pressures up to 17.5 MPa. Diffusion coefficients of carbon dioxide in PVAc were also measured at 313.15 K and pressures up to 7 MPa. Solubilities and diffusion coefficients of carbon dioxide in molten polystyrene (PS) were studied at temperatures from 373.15 to 473.15 K and pressures up to 20 MPa. An apparatus using a magnetic suspension balance (MSB) was constructed for the measurements. The solubilities in the PVAc and the PS were in good agreement with literature data. The solubility in both polymers were correlated with the Sanchez and Lacombe equation of state to within an average relative deviation of 3.6 and 1.6% for PVAc and PS systems, respectively. The diffusion coefficients in PS were correlated with free volume theory of Kulkarni and Stern to within 10% of relative average deviation.

Solubilities of carbon dioxide and nitrogen in polystyrene under high temperature and pressure

The solubilities of nitrogen and carbon dioxide in polystyrene were measured by a pressure decaying method at temperatures from 373.2 K to 453.2 K and pressures up to 20 MPa. The isothermal solubilities of both gases increase almost linearly with pressure. The solubility of carbon dioxide decreases with increasing temperature. The solubility of nitrogen, however, increases with temperature, and is about 116 to 17 of that of carbon dioxide. The solubilities measured are correlated by the Sanchez-Lacombe equation of state using the characteristic parameters for nitrogen and carbon dioxide determined in our previous work. The parameters for polystyrene were determined using the experimental PVT data measured in our laboratory. Agreement between the experimental solubilities and the correlations with a temperature-dependent binary interaction parameter, kij, is satisfactory. Henrys constants for carbon dioxide + and nitrogen + polystyrene systems are in relatively good agreement with Durills data.

Controlling factors and mechanism of reactive crystallization of calcium carbonate polymorphs from calcium hydroxide suspensions

The crystallization was carried out by adding the Na2CO3 solution to the Ca(OH)2 suspension, and the controlling factor and the mechanism of the crystallization of calcium carbonate polymorphs were investigated. The reaction between calcium hydroxide and sodium carbonate proceeded almost with the stoichiometric ratio when the addition rate of Na2CO3 solution was low; however, at fast addition rate calcium hydroxide solids remained even when an excess amount of sodium carbonate was added. This may be due to the limit of the dissolution rate of the calcium hydroxide. Calcite precipitates from the start of the reaction; however, aragonite begins to precipitate at the molar ratio of sodium carbonate to calcium chloride of around 0.3, and the composition of aragonite increases with time and attains a constant value. The alkaline solutions at pH larger than about 13.5 are considered to be advantageous for the nucleation of aragonite. The degree of the solubility of calcium hydroxide may contribute to this behavior. The crystallization of aragonite crystals was accelerated by decreasing the addition rate of sodium carbonate solution and at the fast addition rate calcite crystallized preferentially. On decreasing the addition rate, the amount of aragonite crystals with long needle-like morphology increased. With the increase of the solution volume and the stirring rate, the crystallization of aragonite was also accelerated and the amount of agglomerated fine particles of calcite decreased. These results indicate that if the concentration of calcium ions is at or near the solubility of Ca(OH)2, the low concentration of carbonate ion in the “diffusion field” around the droplets of sodium carbonate solutions (low local supersaturation) is advantageous for the crystallization of aragonite.

Precise measurement of the PVT of polypropylene and polycarbonate up to 330°C and 200 MPa

An apparatus for measuring the pressure—volume—temperature (PVT) properties of polymers using a metal bellows has been developed at temperatures from 313 to 623 K and pressures up to 200 MPa. A calibration of the device was performed by measuring PVT of mercury and water. The experimental uncertainty of specific volumes was estimated to be within ±0.2%, while that of temperatures was within ±0.1 K below 300°C and ±0.3 K above 300°C. The estimated uncertainty of pressures was ±0.1 MPa below 100 MPa and ±0.25 MPa above 100 MPa. The PVT properties of polypropylene and polycarbonate were measured by the apparatus in the temperature ranges from 40 to 300°C and from 40 to 330°C, respectively, and pressures from 10 to 200 MPa. The effects of a sample cup and sample forms were investigated. The use of the sample cup showed a little effect on the measurments of PVT properties for both samples. The shape (pellet and pillar) of the samples caused a small difference in the specific volumes only under high temperatures and low pressures. The PVT properties in a melt state were correlated by the Simha-Somcynsky equation of state, showing a good agreement with measurements.

Improvement of predictive accuracy of the UNIFAC model for vapor-liquid equilibria of polymer solutions

Abstract The UNIFAC model is extended to the prediction of vapor-liquid equilibria of polymer solutions using a proposed relation between the volume parameter r ( n ) for an n -mer polymer and that r (1) for the monomer. The modified UNIFAC model does not require a free-volume term as does the UNIFAC-FV model. As a result, no additional information is needed for the vapor-liquid equilibria Eq. (1a) calculation of polymer solutions other than the original UNIFAC group parameters. For 51 binary polymer-solvent systems, the total average absolute deviation of solvent activities in polymer solutions was 6.8% for the modified UNIFAC model versus 7.4% for the UNIFAC-FV model and 18.7% for the original UNIFAC model.

A new mixing rule for cubic equations of state and its application to vapor-liquid equilibria of polymer solutions

Abstract A new mixing rule for van der Waals-type two-parameter cubic equations of state (EOSs) has been proposed in this work, which is particularly suitable for highly asymmetric systems. The new mixing rule has been applied to the PRSV and SRK EOSs to calculate vapor-liquid equilibria (VLE) of polymer solutions. Compared to the other two mixing rules which have been used for VLE calculation of polymer solutions, the new mixing rule with only one temperature-independent parameter is very accurate for a wide range of temperatures. As the new mixing rule is very simple and accurate and only one temperature-independent parameter is needed, it enables the two-parameter cubic EOSs to be used in the practical calculations needed in the industrial processing of polymer solutions.

Solubility of carbon dioxide in eicosane, docosane, tetracosane, and octacosane at temperatures from 323 to 473 K and pressures up to 40 MPa

Abstract Solubilities of carbon dioxide in eicosane (C 20 H 42 ), docosane (C 22 H 46 ), tetracosane (C 24 H 50 ), and octacosane (C 28 H 58 ) were measured at temperatures from 323.2 to 473.2 K and pressures up to 40 MPa. The solubility increased with pressure and decreased with temperature. At a temperature of 323.2 K, bubble point pressures of carbon dioxide–eicosane and –docosane systems showed a large enhancement around 0.78 CO 2 mole fraction. At the higher temperatures, bubble point measurements were carried out up to the vicinity of the mixture critical points. Prediction of the solubility using the PSRK and the SRK equations of state with two excess Gibbs free energy mixing rules was examined. The mixing rule proposed by Zhong and Masuoka [C. Zhong, H. Masuoka, J. Chem. Eng. Jpn. 29 (1996) 315–322] provided prediction of the solubility with an average absolute deviation of 2.3% and can predict the solubility with satisfactory accuracy except near the mixture critical point.

Solubility of propylene in semicrystalline polypropylene

Gas solubilities and polymer swelling in propylene and semicrystalline polypropylene system at temperatures of 323.2 and 348.2 K and pressures up to propylenes vapor pressure were measured. Pressure, specific volume, and temperature (PVT) measurements of polypropylene were carried out at temperatures from 313 to 573 K and pressures up 200 MPa. Two kinds of polypropylenes, which had different stereoregularities, were used for both solubility and PVT measurements. The solubilities were correlated with the Sanchez–Lacombe equation of state (EOS) with temperature-dependent binary interaction parameters to within 5% average relative percentage deviation. Swelling ratios estimated with Sanchez–Lacombe EOS coupled with optimized interaction parameters were 20% lower than the experimental values.

Modeling of gas solubilities in polymers with cubic equation of state

Abstract The PR equation of state (EOS), as a representative of cubic EOSs, is applied to correlate gas solubilities in molten polymers in this work. Two existing mixing rules, the conventional van der Waals one-fluid mixing rule with one adjustable parameter (vdW1) and that with two adjustable parameters (vdW2), are used to test the capability of the PR EOS. The results show that the vdW1 is not enough, while the vdW2 can give acceptable correlations. A new mixing rule proposed in our previous work, which has been proved to work well for correlating VLE of polymer solutions using cubic EOSs, is further modified here. The new proposed mixing rule with one adjustable parameter shows greatly improved correlations than the vdW1, and is comparable with the vdW2 which requires two adjustable parameters. For 17 systems tested, the total average absolute deviation of pressure for the new mixing rule is 10.0% against 47.8% for the vdW1, and 12.1% for the vdW2.