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INDUSTRIALAND ENGINEERING CHEMISTRY 473 nated rubber, the solvent strength as measurd by the dilution ratio is of considerable importance.2. The compatibility of blown castor oil with chlorinated rubber, some other blown oils, and some alkyds, is dependent upon the strength of the solvent used. Strong solvents as measured by their dilution ratio enhance compatibility.3. No particular plasticizer is best for use with chlorinated rubber. Different plasticizers impart totally different results at different loading percentages. The choice of plasticizers will be dictated by the ultimate properties desired. More frequently than not, the use of two or more plasticizers will be necessary to obtain the optimum properties for any given application. 4. Consideration of the fundamental principles and trends presented in this paper will be helpful in the formulation of chlorinated rubber finishes for a wider variety of uses, and products of an improved nature will be the result.

223 S = channel slope t = time U = mean velocity in z direction v = turbulent velocity component perpendicular to direction of w2 = mean square value of e, Y2 = mean square value of transverse spread of diffusing matter 2 = distance downstream from point a t which diffusing matter mean flow -is injected xo = scale of turbulence defined by Rdx e = kinematic eddy viscosity p = fluid density T = unit shear in fluid LITERATURE CITED (1) Dryden, H. L., IND. ENQ. ONDENSATION products or polymers of C lactic acid are important because: (a) They occur in all aqueous solutions of lactic acid containing approximately 18% lactic acid or more. (b) They are promising chemical intermediates. (c) The condensa-The preparation, properties, and reactions of condensation polymers of lactic acid are reviewed; batch and continuous methods for converting lactic acid into its condensation polymers are described. Removal of water during the dehydration or self-esterification of lactic acid is facilitated by relatively high temperature, reduced pressure, sulfuric acid or similar esterification catalyst, and an entraining agent, such as benzene or toluene. The resulting condensation polymers, which react readily with methanol, are useful for making methyl lactate. tion polymers of intermediate molecular weight can be used as such or after slight alteration as plasticizers. (d) The condensation products of higher molecular weight can be converted into useful plastics by condensation with certain vegetable oils, glycols, and other chemicals. (e) They are excellent for storing and transporting lactic acid in a highly concentrated condition; the completely polymerized linear product (I) and lactide (11) are equivalent to 125% lactic acid:Our interest in the production and properties of polymerized lactic acid was created largely by finding that the linear condensation polymers constitute an excellent starting point for making methyl lactate (19). When methyl lactate is formed by the interaction of polylactic acid and methanol, probably alcoholysis as well as esterification is involved, and only small quantities of water are formed in the reaction. Absence of water is advantageous because methyl lactate is readily hydrolyzed during distillation when appreciable quantities of water are present. Moreover, methyl lactate and water distill as an azeotropic mixture. The present paper summarizes earlier information on polylactic acid, much of which (3, 6) has not been readily available and describes both batch and continuous methods for dehydrating or polymerizing lactic acid. PREVIOUS INVESTIGATIONSAlthou h the reported findings o f previous workers are not in complete agreement, aqueous lactic acid solutions and dehydrated lactic acid appear to consist mainly of "free lactic acid:' (monomeric a-hydrox onic .acid), water, an^^^^^^ condensation or self-esterification products, such as lactyl lactic acid and lactyl lactyl lactic acid, 111: HOCH(CHs)COOCH(CHs)COOCH(CHs)COOH (111)These three components occur in various proportions, the extreme limits b...

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Articles you may be interested inOptogalvanic signal in the BX system of HgBr: Effect of discharge voltage and laser power AIP Conf.A kinetic model of the sustained discharge HgBr laser Geometrical considerations are important with respect to the stability and efficiency of avalanche electric discharge lasers. Parameters such as the electrode contours and the distribution of preionization electrons affect excitation rates through the relative values of the local electric field, local depletion of initial species, and through the response of the discharge circuitry to spatially dependent conditions within the plasma. Constriction of the discharge and subsequent impedance mismatch of the discharge to the pulse forming line result from these spatial nonuniformities. In this paper geometrical effects in the mercury bromide electric discharge laser are examined by comparing the results from a multidimensional discharge and kinetics model with experimental observations. The code models electron and heavy particle kinetics and laser intensity in time and one spatial dimension: parallel to the electrodes and perpendicular to the optical axis. Quantities whose spatial dependence is perpendicular to this dimension, such as the contours of the electrodes, are accounted for through their impact on the local electric field. HgBr laser efficiency and spatial characteristics are examined as a function of stored electrical energy, the impedance of the pulse-forming circuitry, electrode contours, and profile of the preionization electron density. Parasitic discharges within the gas, but exterior to the optical cavity, are examined as a mechanism through which the magnitude of the preionization density can effect laser efficiency.