A.A. Tager

Effect of the type of polymer and solvent on the rheological properties and structure formation of polymer concentrates

Abstract This communication describes the results of examining the influence of concentration, type of solvent, and temperature on the rheological properties of polymer concentrates having differing flexibilities of macromolecules of a wide range of stresses and shear velocities.

Phase equilibrium and light scattering in polymer solutions

3. M. LIDARIK and S.~STARY, Plaste and Kautschuk U: 586, 1964 4. B. A. ROZENBERG, S. S. MEDVEDEV, O. M. CHEKHUTA, Ye. B. LYUDVIG and A. R. GANTMAKHER, Vysokomol. syoed. 6: 2030, 1964 (Translated in Polymer Sci. U.S.S.R. 6: 11, 2246, 1964) 5. A. I. NEPOMNYASHCHII, G. V. BELOUSOVA, F. M. SMEKHOV and A. A. BLAGONRAVOVA, Lakokrasochnye materialy i ikh primeneniye, No. 4, 10, 1966 6. F. M. SMEKHOV, A. I. NEPOMNYASHCHII, E. I. AVERBAKH and I. V. SURIKOV, • Zavod. lab. 32: 1159, 1966 7. L. V. NITSBERG, S. M. FIRGER and L. A. BOBINA, Lakokrasochnye materialy i ikh primeneniye, No. 6, 41, 1966 8. Yu. L. RIVLINA, Yu. M. MALINSKII and S. V. YAKUBOVICH, Lakokrasochnye materialy i ikh primeneniye, No. 6, 31, 1961 9. A. I. NEPOMNYASHCHH, A. A. BABUSHKIN, A. A. BLAGONRAVOVA and S. A. GAVRILINA, Zh. fiz. khimii 37: 2462, 1964 10. B. A. ROZENBERG, Ye. B. LYUDVIG, N. V. DESYATOVA, A. R. GANTMAKHER and S. S. MEDVEDEV, Vysokomol. soyed. 7: 1010, 1965 (Translated in Polymer Sci. U.S.S.R. 7: 6, 1116, 1965) 11. S. N. KOLESOV, Vysokomol. soyed. 8: 650, 1966 (Translated in Polymer Sci. U.S.S.R. 8: 4, 113, 1966) 12. G. P. MIKHAILOV, Makromolek. Chem. 35: 26, 1960

Thermodynamics of mixing polymers

Abstract Free energies Δg x , enthalpies Δh x and entropies TΔs x of mixing were calculated for eight polymer-polymer systems. It was shown that the polymer compositions studied, in respect of the shape of the curve showing the concentration dependence Δg x , may be classified in three groups: stable, metastable and unstable. For a stable cellulose nitrate-polyvinylacetate system a reduction in entropy was observed during mixing, which may be due to ordering of elements of the system. For metastable systems thermodynamic functions of mixing Δh x and TΔs x are positive in one range of composition and negative in the other. An unstable polymethylmethacrylate-polybutylmethacrylate system undergoes endothermic mixing over the entire range of composition and the free energy varies positively and entropy of mixing increases in this case.

The thermochemistry of polymer solutions and compositions in the phase separation region

The heats of mixing of oligomeric polyoxypropylenediol (POPD) with water and of the following polymers: cellulose nitrate (NC) with polyvinylacetate (PVA), NC with cellulose acetate (CA), CA with PVA and polyvinylchloride (PVC) with polymethyl-methacrylate (PMMA) have been obtained in the region of phase separation. For the polymer compositions the heats of mixing were calculated according to Hesss law, fow which the heats of solution of the polymers and polymer mixtures in a common solvent were determined. The POPD-water system, which has a lower critical temperature of mixing (LCTM) is exothermic over the entire range of compositions and temperatures. At T LCTM) the curves contain a linear section. The curves of the concentration dependence of the enthalpy of mixing of NC with PVA are uninterrupted and the system is exothermic. The enthalpy of mixing-composition curves of the other polymer compositions contain a linear section, indicating phase separation. Analysis of the curves showed that the temperature coefficients of solubility of each component in the two layers have the same sign, which is possible only if there is one sided diffusion of one of the components. From the evidence presented it follows that PVC diffuses into PMMA, CA into NC and CA into PVA. This is accompanied by loosening up of one part of the transitional layer (in which diffusion takes place), with an endothermic effect, and compacting of the other part of the transitional layer, with an exothermic effect. This is in good agreement with the ideas developed by Voyutskii and Kuleznev.

Thermodynamic studies of reactions in filler containing polyvinyl chloride

Abstract Microcalorimetry and isothermal sorption have been used to study the enthalpy, free energy and entropy of the PVC reactions with aerosil, white carbon, chalk and kaolin. The thermodynamic parameters of these reactions were found to change a lot with the amount of filler and its chemistry. Negative heats and entropies of reaction in the range of low filler contents other than chalk are explained by the formation of adsorbed and oriented PVC layers on the filler surfaces. The positive values of these are typical for the system PVC-chalk as well as for larger contents of aerosil, white carbon and kaolin; they indicate the lack of any thermodynamic affinity of the components for each other and the thermodynamic instability of such compositions.

Temperature relation of thermodynamic functions of combining polymer systems with upper and lower critical temperatures of mixing

Abstract An apparatus was designed to measure vapour pressure over polymer solutions at high temperatures and pressures. Vapour pressures of solvents were measured above their boiling points for polyisobutylene (PI) solutions in iso-octane and benzene and polystyrene (PS) solutions in ethylbenzene and cyclohexane at temperatures of 25 to 165° in a wide range of concentration. Values of Δμ 1 , Δμ 2 and average free Energies, enthalpies and entropies of mixing and combinatorial values of S c and non-combinatorial entropies of mixing S nc were calculated. It was shown that for systems only having a lower critical temperature of mixing, long before this value is achieved, the thermodynamic affinity between components decreases continuously with an increase in temperature and enthalpies and entropies of mixing are negative over the entire range of temperature and concentration. For systems with upper and lower critical temperatures of mixing (CTM) thermodynamic affinity varies with temperature according to a curve with a minimum, decreasing in absolute value on approximating CTM. On increasing temperature, enthalpies and entropies of mixing change sign (from positive to negative). It was shown that for solutions of PI in iso-octane the non-combinatorial entropy of mixing is responsible for the variation of entropy of mixing with temperature and depends on the interaction between components. ΔS nc ∂ΔS nc / ∂T ΔS c is always positive and independent of temperature.

Effect of the thermodynamic affinity of plasticizers for polyvinyl chloride on the heat of its interaction with fillers

Abstract A microcalorimeter of the Calve type has been used to determine the heats of swelling of PVC in four plasticizers and heats of wetting by the latter of chalk, kaolin and Aerosil and the heats of the interaction of plasticized PVC with these fillers. It is shown that the energy interaction of PVC with the filler is due to the competing influence of its heats of swelling in the plasticizers and the heats of wetting by the latter of the fillers. For identical thermodynamic affinity of the plasticizers for PVC the global thermal effect of the interaction of plasticized PVC with filler is more negative the greater the heat of wetting by the plasticizer of the filler. For identical heats of wetting by the plasticizers of the PVC filler the worse PVC interacts energetically with the filler, the greater the thermodynamic affinity of the plasticizer and the greater the heat of swelling of PVC.

Effect of inorganic salt additives on the viscosity of cellulose acetate solutions

Abstract A study of the effect of Li, Na, Mg, Ca, Sr, Ba, La perchlorates and Li chloride and nitrate on the viscosity of 22% secondary cellulose acetate (CA) solutions in acetone, aqueous acetone mixtures and DMF shows that on increasing the amount of salt dissolved, the higher the valency of the cation, the greater the extent to which solution viscosity increases. This is the result of the formation of donor-acceptor bonds between cations of salts and donor solvents and between cations and donor groups of the CA chain; as a consequence solution cross linking increases. The anions are unable to provide solvated complexes with donor solvents (DMF and acetone) and therefore have no effect in practice on the viscosity of CA solutions in these solvents. In the presence in the solution of fairly large amounts of water the dependence of solution viscosity on the amount of salt added is expressed by a curve with a maximum, which is due to the competing ordering action of Mg 2+ cations and the disorganizing effect of perchlorate of the anion.

The effect of temperature on the water solubility of polyvinyl alcohol

QUITE a number of the reports published on polyvinyl alcohol (PVA) deal with its aqueous solutions, bu t there is still no clear knowledge of the effect cf tempera ture on the miscibili ty of the two substances. One of the invest igators indicated t h a t the solubili ty of P V A in water increases as a funct ion of t empera tu re [1]; while others reckon t h a t PVA dissolves bet ter in water during cooling [2, 3]. This contradic t ion was due firstly to the PVA samples used in these studies having had different numbers of acetyl groups, which must have affected their solubility in water, and secondly to the fact tha t different invest igators worked with solutions in different ranges of t empera ture and composition. The work described in this paper aims at s tudying the miscibili ty of P V A with water in a wide range of t empera tu re and composition. Apar t f rom the composi t ion d iagram of this system, we also examined the t empera tu re coefficients of light scat ter ing and of t h e r m o d ~ l a m i c affinity of the components .

Estimation of the packing density of solid polymers—IV. Isotactic polystyrene

From paper [1] it follows that atactic, amorphous, “glassy” polystyrene during sorption acts as an ultra-microporous sorbent, the summary pore-volume of which is 0.03 cm3/g. Such behaviour of atactic polystyrene is tied to loosely-packed, irregular, chain construction, randomly disposed in space, as with the larger phenyl substituted compounds. From this point of view, the study of the sorptive ability of isotactic polystyrene presented great interest. The present work was devoted to an investigation of the sorption of methyl alcohol vapour on amorphous and crystalline samples of isotactic polystyrene. From the Department of High Molecular Compounds in the Moscow State University we obtained samples of isotactic polystyrene which were freed from catalyst by boiling with toluene, followed by precipitation of pure, amorphous polystyrene with methyl alcohol. Crystallization of the polystyrene was carried out by heating for 5 hours at 116° in n-octane. The molecular-weights of the samples under investigation were determined by viscometry in benzene solutions. The dissolution of crystalline polystyrene was carried out at a temperature of 60°. In the calculation of the molecular weights the equation (η)=1.13 × 10−4M0.73 was used [2].