VISCOSITY OF POLYALKYL METHACRYLATE PLASTICIZED WITH DIETHYL PHTHALATE. I. POLY-n-BUTYL METHACRYLATE

Abstract

A. TERAMOTO, R. OKADA, AND H. FUJITA Vol. 67 indicate that equation 4 instead of equation 5 should be used to evaluate the electrophoretic effect. Kay and Dye5 reached the same conclusion in their analysis of data for the alkali halides. These results also indicate that the inclusion of the (1 + FC) term cannot be used to explain the rather lorn d values obtained for the relatively large ions involvedo. For example, if 8 ( J ) for Bu4n'Cl is increased by 1 A. due to the inclusion of this term, A, as calculated from equation 4 would be 0.25 lower than the experimental value obtained from transference numbers. This is a significant difference and indicates that the same values of 8 would not fit both conductance and transference data. This result will cast considerable doubt on the validity of the 1 + FC term for nitromethane solutions if it is shown from viscosity measurements to be large. Since equation 4 rather than equation 5 appears to give the better evaluation of the electrophoretic effect, possibly a better method of handling equation 6 would be t o plot A* given by against C/(1 -~Y C~'~) using an initial value of d to calculate he if transference data are not available. From the slope J' a better value of d could be obtained and convergence should be rapid since he is insensitive to 8.The viscosity of a sample of poly-n-butyl methacrylate (PBMA) in diethyl phthalate (DEP) was measured, using six different kinds of viscometer, over the complete range of composition ( i e . , 0 to 100% in polymer weight fraction) and over the temperature range from 0 to 120'. Plots for the logarithm of viscosity os. weight fraction of polymer a t temperatures above 60' showed a curvature convex downward in the region approaching pure solid. This type of viscosity-concentration relation had not been observed in previous studies on other typical amorphous polymers, but is similar to that found very recently for polyethylene mixed with low molecular weight paraffin. The free volume theory of Fujita and Kishimoto for the viscosity of very concentrated solutions of an amorphous polymer has been modified so that effects of the density of chain entanglements may be taken into account. The assumption that the free volumes of polymer and plasticizer are additive has also been discarded. Instead, it has been assumed that the free volume of a given polymer-plasticizer mixture increases linearly with temperature. The free volume theory SO modified was found to account well for experimental data in the region where the volume fraction of DEP is snialler than about 0.2. Beyond this limit the analysis in terms of the modified theory led to an anomalous conclusion that the dilution of the density of chain entanglements produces an increase of the viscosity of this polymer-plasticizer system. This appears to indicate that the range of concentration in which the free volume theory may be applied may not be as wide as so far supposed.

Free volume treatment of concentrated polymer solutions

“…' However, it has been found experimentally that the F-K equations can be applied only within quite narrow ranges of concentration, typically between the pure polymer of & = 0.8.53. 9 It is known the WLF equation applies to pure polymers having fractional free volume less than 0.08, and Ferry and Stratton4 have supposed that a similar limitation should also hold for the concentrated solutions of polymers, so that the above F-I< treatment should riot be applicable to concentrations less than 0.8 by v01ume.~…”

“…I n the Kelley-Bueche (hereafter referred to as K-B) treatment2 the viscosity of a solution of entangled macromolecules is given by 71 = k&4M3.45 (9) which, combined with eqs. (2) and (5) (10) can be written…”

“…I n the Kelley-Bueche (hereafter referred to as K-B) treatment2 the viscosity of a solution of entangled macromolecules is given by 71 = k&4M3.45 (9) which, combined with eqs. (2) and (5) (assumption of the Doolittle equation for 5 and of the additivity of free volumes) gives In (7/k1143.4) = 4 In h + (f242 + fi4d-' (10) The validity of the treatment is tested in the following way.…”

Thermodynamic characteristics of the interaction coefficient from plasticizer viscosity measurements for the generalized viscosity model

“…Several studies in the literature (Ferry et al, 1954;Spencer and Williams, 1947;Bueche, 1953Bueche, , 1955Brockmeir and Westphal, 1974;Teramoto et al, 1963) have also evaluated the viscosity of suspensions and/or solutions over very large concentration ranges. However, only a limited number of studies in the literature (Bueche, 1955;Brockmeir and Westphal, 1974; The current issue and full text archive of this journal is available at www.emeraldinsight.com/0369-9420.htm The author would like to acknowledge the Aldrich Chemical Company, Inc. for supplying the viscosity data of diethyl phthalate at different temperatures that was presented in this study.…”

“…However, only a limited number of studies in the literature (Bueche, 1955;Brockmeir and Westphal, 1974; The current issue and full text archive of this journal is available at www.emeraldinsight.com/0369-9420.htm The author would like to acknowledge the Aldrich Chemical Company, Inc. for supplying the viscosity data of diethyl phthalate at different temperatures that was presented in this study. Teramoto et al, 1963) that have actually evaluated the viscosity of suspensions or solutions over the whole concentration range from 0 to 100 per cent solute. This later observation is particularly important since many practical applications for plasticized polymers often require the evaluation of viscosity at very high concentrations of polymer or very low concentrations of plasticiser.…”