Article pubs.acs.org/jced
Theta Temperatures of Chlorinated Poly(propene) Solutions Siye Tang*,† and Xueru Dong‡ †
College of Chemistry and Chemical Engineering, Luoyang Normal College, Luoyang 471022, Henan China Department of Materials and Chemical Engineering, Henan Institute of Engineering, Zhengzhou 451191, Henan, China
‡
ABSTRACT: The aim of this work is to determine the theta temperatures of chlorinated poly(propene) solutions. The cloud point temperatures of chlorinated poly(propene) in ethyl acetate, butanone, and 1,4-dioxane solutions were determined at various concentrations. The theta temperatures of chlorinated poly(propene) solutions were determined by the linearity of the reciprocal cloud point temperature against the logarithm of the polymer volume fraction. The theta temperatures of chlorinated poly(propene) in ethyl acetate, butanone, and 1,4dioxane solutions are 353.11 K, 347.95 K, and 335.91 K, respectively. The theta temperature increases with the decrease of solubility. The lower the solubility of chlorinated poly(propene) in solvent, the larger is the free energy of mixing, the weaker is the spontaneous dissolution, and the higher is the theta temperature.
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ethyl acetate, butanone, and 1,4-dioxane were 0.9000 g·cm−3, 0.7997 g·cm−3, and 1.0337 g·cm−3 at 293.15 K, respectively. All reagents were used directly without further purification. Apparatus and Procedure. A DHG-9070A electric constant temperature drying oven, which was made by Shanghai (China) YiHeng Technology Controlled Limited Company, was used to determine the cloud point temperature of CPP solutions. The drying oven includes a programmed temperature controller.The temperature of the drying oven was thermostatically controlled. The drying oven has an uncertainty of ± 0.01 K. CPP was dissolved in a given solvent at different concentrations. CPP solutions were prepared by mass using an electronic balance (type AEU-210, Japan). The balance has an uncertainty of ± 0.0001 g. Taking into account the dissolution equilibrium, the sealed solution was allowed to stand for three days before measurements were performed. The solutions were shaken for a certain time. In the case of solvent in which the solute did not appear to dissolve at room temperature, heat was applied and then cooled to room temperature. It was ensured that the solutions were homogeneous. The heating temperature was below the boiling point of the corresponding solvent. The homogeneous solutions were put into the drying oven at atmospheric pressure. Cloud point temperatures were determined visually as the temperatures at which clear solutions suddenly turned opaque on cooling or slightly hazy solutions suddenly turned clear on heating. Each sample was subjected to three successive heating and cooling cycles.6 The reproducibility of the six cloud point measurements was excellent within the range of ± 0.1 K. The sealed solutions were heated and cooled at a rate of 0.2 K·min−1, since it had been confirmed that cloud points
INTRODUCTION Since their molecular weight is large, most polymer solutions do not behave as ideal solutions. Even if a polymer solution is very dilute, it cannot be regarded as an ideal solution.1 This is inconvenient to researching polymer solutions. Only at the theta temperature (Flory temperature or ideal temperature) a dilute polymer solution presents ideal behavior. At the theta temperature, a polymer solution has the same thermodynamics properties as an ideal solution, and the laws that apply to an ideal solution can apply to a polymer solution.1−3 Therefore, determining the theta temperature is valuable for investigating properties of a polymer solution. Chlorinated poly(propene) (CPP) has an excellent adhesion to polyolefin. As an adhesion promoter, CPP is widely used in polyolefin coatings, agglutinants, printing ink, and in compatibility assistants, and so forth. CPP is usually used in solvents, so a study on the properties of CPP in various solvents is required.4,5 However, as far as we know, no theta temperature data of CPP solutions are available in the open literature. Since ethyl acetate, butanone, and 1,4-dioxane are widely used in industry and are solvents of CPP, the aim of this work is to determine the theta temperature of CPP in these solvents, which provides valuable basic data for its further application.
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EXPERIMENTAL SECTION Materials. CPP, which contains 30 % chlorine by weight, was a commercial product purchased from Jin Zhujiang Chemical Factory in Guangdong (China). It had a weightaverage molecular weight of Mw = 183 400 g·mol−1 and a number-average molecular weight of Mn = 93 010 g·mol−1. The polydispersity is 1.972. The density of CPP was 1.0985 g·cm−3 at 293.15 K. The density of CPP was measured using a pycnometer. Ethyl acetate (more than 99.5 % pure), butanone (more than 99.5 % pure), and 1,4-dioxane (more than 99.5 % pure) were purchased from Tianjin Kermel Chemical Reagents Development Center. They were of analytical grade. The densities of © 2012 American Chemical Society
Received: January 3, 2012 Accepted: March 27, 2012 Published: April 6, 2012 1499
dx.doi.org/10.1021/je300009n | J. Chem. Eng. Data 2012, 57, 1499−1501
Journal of Chemical & Engineering Data
Article
Table 1. Cloud Point Temperatures of CPP (Tcp) in Different Solvents as a Function of Polymer Volume Fractions (φ2) solvent ethyl acetate mass fraction/%
−2
volume fraction φ2·10
1.00 2.50 4.00 5.50 7.00 8.50 10.00 11.50 13.00 14.50 16.00 17.50 19.00
0.82 2.06 3.30 4.55 5.81 7.07 8.34 9.62 10.91 12.20 13.50 14.81 16.12
butanone Tcp/K
−2
volume fraction φ2·10
330.40 336.20 338.20 339.70 340.20 340.95 341.50 342.15 342.65 343.10 343.55 343.95 344.50
0.73 1.83 2.94 4.06 5.19 6.33 7.48 8.64 9.81 10.99 12.18 13.38 14.59
1,4-dioxane Tcp/K
volume fraction φ2·10−2
Tcp/K
329.60 331.90 333.70 334.80 335.45 336.95 337.50 337.85 338.45 338.90 339.70 340.65 341.10
0.94 2.36 3.77 5.19 6.61 8.04 9.47 10.90 12.33 13.76 15.20 16.64 18.08
316.70 318.70 321.25 322.65 323.25 324.05 325.75 326.30 326.85 327.05 327.55 328.15 328.60
obtained under such a condition were free from the influence of the rate of heating or cooling. To ensure the absence of leakage, the sealed solutions were weighed before and after the cloud point temperature measurement.6 Taking into account the thermal balance, each temperature was kept for 35 min. The procedure used depends on the reciprocal of cloud point temperature (1/Tcp) being linearly related to the logarithm of polymer volume fraction (log ϕ2), and the extrapolation to log ϕ2 = 0 gives the reciprocal of the theta temperature.3,7,8 The volume fraction was calculated by the following equation: φ=
Figure 2. Relation between the reciprocal of cloud point temperature 1/Tcp and the negative logarithm of polymer volume fraction, −log φ2, for CPP + butanone solution.
mp /ρp mp /ρp + ms /ρs
(1)
where mp and ms are the mass of CPP and the solvent, respectively. ρp and ρs are the density of CPP and the solvent, respectively. The uncertainty of the volume fraction was estimated to be ± 0.001 %.
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RESULTS AND DISCUSSION Cloud point data of CPP solutions are listed in Table 1. Figures 1 to 3 show the linearity of 1/Tcp when plotted versus log ϕ2. Figure 3. Relation between the reciprocal of cloud point temperature 1/Tcp and the negative logarithm of polymer volume fraction, −log φ2, for CPP + 1,4-dioxane solution.
Tang measured the solubility of CPP in different solvents at 298.15 K in a previous work.9 The results are also listed in Table 2. Theta Temperatures, Solubilities of CPP, Regression Coefficients, Interaction Parameters χ12, and the Average Free Energy of Mixing ΔFm of CPP Solutions
Figure 1. Relation between the reciprocal of cloud point temperature 1/Tcp and the negative logarithm of polymer volume fraction, −log φ2, for CPP + ethyl acetate solution.
solvent
Table 2 gives the linear regression coefficients and theta temperatures. From Table 2, the correlation coefficients are very good. This indicates that the theta temperatures are accurate. As demonstrated in Table 2, the theta temperature decreases from ethyl acetate to 1,4-dioxane. 1500
parameter
ethyl acetate
butanone
1,4-dioxane
theta temperature/K regression coefficient solubility (298.15 K)/(g·mL−1) χ12(298.15 K) average of ΔFm/kJ·kmol−1 (298.15 K)
353.11 0.9908 0.011 0.59 −104.74
347.95 0.9905 0.039 0.40 −129.02
335.91 0.9907 0.050 0.27 −195.76
dx.doi.org/10.1021/je300009n | J. Chem. Eng. Data 2012, 57, 1499−1501
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valid for the entire range of ethoxylation. J. Colloid Interface Sci. 2003, 260, 219−224. (7) Betül, K.; Güner, A. Effect of phenolic cosolutes on the main parameters, phase separation and theta temperature of dilute aqueous poly(N-vinyl-2-pyrrolidone) solutions. Eur. Polym. J. 2001, 37, 361− 365. (8) Ataman, M. Properties of aqueous salt solutions of poly(ethylene oxide)-cloud points, θ temperatures. Colloid Polym. Sci. 1987, 265, 19− 25. (9) Tang, S. Y.; Liu, D. Z.; Fan, Z. L. Determination of threedimensional solubility parameters of chlorinated poly(propene) by ultrasonic degradation. Phys. Chem. Liq. 2006, 44, 531−542.
Table 2. It can be seen that the theta temperature decreases with the increase of solubility. As we know, the thermodynamics of polymer solution indicates that whether a polymer dissolves in a solvent spontaneously is decided by the Gibbs free energy of mixing.1 By means of the lattice theory, Flory−Huggins applied the statistical thermodynamics to deduce the following equation: ΔFm = RT (n1 ln ϕ1 + n2 ln ϕ2 + χ12n1ϕ2)
(2)
where ΔFm is the Gibbs free energy of mixing; R is the gas constant, and T is the kelvin absolute temperature; n1, φ1 and n2, φ2 are the number of moles and the volume fraction of the solvent and the polymer, respectively; χ12 is the Flory−Huggins interaction parameter. Tang et al. calculated the values of χ12 between CPP and its solvents at 298.15 K.9 The results of χ12 as well as the values of ΔFm calculated by eq 2 are also listed in Table 2. As seen in Table 2, the value of ΔFm decreases, and the solubility increases from ethyl acetate to 1,4-dioxane. This indicates that the spontaneous dissolution becomes strong with the increasing solubility. In the meantime, the strong spontaneous dissolution results in that theta condition becomes easy. Accordingly, the theta temperature decreases from ethyl acetate to 1,4-dioxane. Namely, the theta temperature decreases with the increase of solubility. The concrete relation between theta temperature and solubility as well as other factors will be given in the future.
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CONCLUSION The theta temperatures of CPP solutions have been determined. The theta temperatures of CPP in ethyl acetate, butanone, and 1,4-dioxane solutions are 353.11 K, 347.95 K, and 335.91 K, respectively. The theta temperature decreases with the increase of solubility.
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AUTHOR INFORMATION
Corresponding Author
*Tel.: +86-379-69819162. E-mail address:
[email protected]. Funding
The authors are pleased to acknowledge the financial support of Education Department Science Funds of Henan Province (No. 2008A530002). Notes
The authors declare no competing financial interest.
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REFERENCES
(1) He, M. J.; Chen, W. X.; Dong, X. X. Polymer Physics; Fu Dan University Press: Shanghai, China, 1990. (2) Güner, A.; Kibarer, G. The important role of thermodynamic interaction parameter in the determination of theta temperature, dextran/water system. Eur. Polym. J. 2001, 37, 619−622. (3) Güner, A.; Muhammed, K. Cloud points and θ temperatures of aqueous poly(N-vinyl-2-pyrrolidone) solutions in the presence of denaturing agents. Polymer 1998, 39, 1569−1572. (4) Tang, S. Y.; Liu, D. Z. Effect of concentration on ultrasonic degradation of chlorinated poly (propene). Adv. Technol. Mater. Mater. Process. J. 2006, 8, 180−187. (5) Tang, S. Y.; Liu, D. Z.; Wang, J. J.; Wang, H. Y. Densities and viscosities for binary mixtures of chlorinated poly(propene) with toluene, tetrahydrofuran, chloroform, carbon tetrachloride, and 2butanone at (298.15, 308.15, and 318.15) K. J. Chem. Eng. Data 2006, 51, 2255−2259. (6) Schott, H. A linear relation between the cloud point and the number of oxyethylene units of water-soluble nonionic surfactants 1501
dx.doi.org/10.1021/je300009n | J. Chem. Eng. Data 2012, 57, 1499−1501
