Mechanism of thermal stabilizers for poly(vinyl chloride). II. Synergistic effect of combination of metal soaps

The esterification of metal soaps, in the combination of zinc and calcium soaps, on poly(vinyl chloride) (PVC) has been carried out both in liquid and solid phase to determine why the reactivity of zinc soap decreases on addition of calcium soap, improving the long-run heat stability of PVC and causing the well-known synergism. It is suggested as the mechanism of synergism that metal soaps having low ionization-potential values, such as calcium soap, act as ester-exchangers of metal chlorides, such as zinc chloride, which is generated after the stabilization of PVC, and also decrease the reactivity of the zinc soap by forming a complex, as that of zinc soap—calcium soap. If a third material, such as organic ester silane, reacting as ester-exchanger on zinc chloride and preventing the formation of a zinc—calcium soap complex, is added to the system, these compounds have an excellent synergistic effect.     

Mechanism of the thermal stabilization of poly(vinyl chloride) with metal carboxylates and epoxy plasticizers

The chemical reactions responsible for the retardation of thermal discoloration in poly(vinyl chloride) (PVC) stabilized with a combination of an epoxy plasticizer and a heavy metal soap mixture of Group IIa and IIb metals have been studied. Allylic chlorides (a mixture of 4-chlorohexene-2 and 2-chlorohexene-3) are used as prototypes for the degrading segment of the polymer chain. The results confirm earlier reports that, when a mixture of a covalent and ionic metal soap is used as the stabilizer, the covalent moiety (e.g., Cd and Zn soaps) functions to esterify the allylic site of the degrading PVC model. A synergistic effect displayed by the ionic soap (e.g., Ca or Ba) is caused by a transfer of carboxylate ligands from the ionic soap to the depleting covalent species, which has been largely converted to the corresponding chloride. When an epoxy plasticizer model (cyclohexene oxide) is used in conjunction with the metal soap stabilizer, the preferred reaction is esterification. After a considerable build-up of ester, an α-chloroether, 2-hexenyl 4-(2-chlorocyclohexyl) ether, is formed by the reaction of cyclohexene oxide with the PVC model. This reaction was found to be catalyzed by cadmium chloride. The esterification and etherification reactions provide an explanation for the synergism observed in the stabilization of PVC containing a combination of an epoxy plasticizer with a covalent and an ionic metal soap.     

A study of the surface tension of the systems: “Water-lithium soaps and butanol-I”

Summary The surface tension of the solutions of lithium salts of fatty acids in the mixtures of water and butanol-I of varying composition has been studied. It has been suggested that the change in the nature of the micelles takes place at about 50% butanol-I concentration. Up to 50% butanol-I concentration hydrophilic oleomicelles are formed but above 50% butanol-I concentration lipophilic hydromicelles exist. A study of the effect of the concentration of the different soaps on the surface tension suggests that the surface tension of the solutions increases with the increase in the soap concentration. It has also been observed that the surface tension of the soap solutions increases with the increase in the number of carbon atoms in the soap.     

Dependence of the stability of a soap stock emulsion on the combined effect of sodium chloride and nonionogenic surfactant additives

Qualitative and quantitative compositions of soap stock were estimated by analytical methods and gas-liquid chromatography. The fat component of soap stock was isolated by conversion of the oil-in-water emulsion of the waste into that of the water-in-oil type under a combined effect of an electrolyte (sodium chloride) and a nonionogenic surfactant, oxyethylated nonylphenol (OP-7). A conclusion was made, on the basis of values obtained for the compression coefficient β and surface pressure π, that the emulsion system is hydrophobized and the linoleic acid monolayer contracts upon addition of sodium chloride and OP-7.     

Kinetics and mechanism of the emulsion polymerization of styrene in the aqueous media at 50°C and at low monomer concentration initiated by persulfate. I. Initiation

The mechanism of the water-soluble persulfate-initiated emulsion polymerization of styrene in the aqueous media at 50°C has been investigated kinetically by the conventional dilatometric and gravimetric methods at low concentration of the monomer (5% v/v). It has been found that the initial rate of polymerization V_p is approximately proportional to initiator concentration [I] to the 0.50 power, i.e., V_p ∝ [I]^0.50, and the viscosity-average molecular weight M _v is approximately inversely proportional to the 0.50 power of the initiator concentration, i.e., M _v ∝ [I]^?0.50. With the progress of the reaction, the initiator exponent of the reaction rate equation decreases gradually from 0.50 to 0.25, but that of the molecular weight (1) equation remains constant up to 20% conversion and thereafter begins to decrease. Since the kinetic data at zero conversion satisfy the steady-state kinetics of the free-radical-initiated homogeneous vinyl polymerization, it is suggested that the initiation of emulsion polymerization of styrene is a two-step process. It starts in the aqueous phase by the primary free radicals from the water-soluble initiator or secondary free radicals derived from the soap molecules. The second step occurs in the monomer-leaded micelles by the water-soluble or water-insoluble macroradicals or by radicals derived from the soap molecules. The latter are likely to be produced in the aqueous phase by the oxidation of soap with S₂O₈^2?ions or SO₄^? radicals. It has been noted that the rate of thermal decomposition of persulfate increases by a factor of 6–8 times under different experimental conditions in the presence of soap.     

Co-melting of solid sucrose and multivalent cation soaps for solvent-free synthesis of sucrose esters

Sucrose fatty acid esters, useful as mild surfactants, have been synthesised in good yields in a solvent-free medium. High contents of monoesters and low saponification rate have been observed. The co-melting of sucrose and a multivalent cation soap such as magnesium or zinc soaps, under basic conditions, allowed the formation of a homogeneous reaction mixture, where solid sucrose was fully dissolved. The kinetic monitoring profiles are similar to reactions in homogeneous solutions, with fast initial formation of monoesters. As a consequence, conversion of sucrose in sucrose esters occurred in good yields. The specificity of multivalent cation soaps compared to monovalent cation soaps, for example, potassium stearate, was pointed out.     

A study of conductivity of the systems: Water-0.2 N sodium salts of fatty acids and Butanol-I presence of free acids and alkali (Part I)

Summary The electrical conductance of the systems Water-0.2N sodium salts of fatty acids (sodium caprylate and caprate) and Butanol-I at different concentrations of Butanol-I has been studied. The effect of free acid has also been studied with a view to determine its effect on the behaviour of these systems. It has been concluded that two types of micelles are formed in such systems. Up to 50% Butanol-I concentration hydrophilic oleomicelles exist and above 50% Butanol-I concentration lipophilic hydromicelles are formed. It has also been observed that the conductivity of the solutions decreases with the increase in Butanol-I concentration as well as with the increase in the chain length of the soap. The results are in aggreement with viscosity and surface tension results of these systems.     

Rubbing-induced surface textures in nematic MBBA layers and their behaviour under applied d.c. or a.c. voltages

Surface irregularities (for example, rubbing-induced domains, and bumps) have been observed in MBBA nematic cells after special treatment of the electrodes using a conventional soap. Various techniques such as polarizing microscopy, the shadowgraph technique and computer processing of the images have been used. The behaviour of the rubbing-induced domains under a.c. or d.c. electric fields has been studied. A new flexoelectric effect has been observed leading to the dividision of the rubbing-induced domains. A simple model has been proposed (a modification of the Saupe model), which explains the structure and dividision of the rubbing-induced domains.     

Rubbing-induced surface textures in nematic MBBA layers and their behaviour under applied d.c. or a.c. voltages

Surface irregularities (for example, rubbing-induced domains, and bumps) have been observed in MBBA nematic cells after special treatment of the electrodes using a conventional soap. Various techniques such as polarizing microscopy, the shadowgraph technique and computer processing of the images have been used. The behaviour of the rubbing-induced domains under a.c. or d.c. electric fields has been studied. A new flexoelectric effect has been observed leading to the dividision of the rubbing-induced domains. A simple model has been proposed (a modification of the Saupe model), which explains the structure and dividision of the rubbing-induced domains.     

Solubility of sodium soaps in aqueous salt solutions

The solubility of sodium soaps in dilute aqueous salt solutions has been systematically investigated by direct visual phase behavior observations. The added electrolytes, including simple inorganic salts and bulky organic salts, influence the solubility of sodium soaps in water, as represented by the varied soap Krafft point. Two inorganic salts, sodium chloride and sodium perchlorate, demonstrate a "salting-out" property. On the other hand, tetraalkylammonium bromides show an excellent ability to depress the soap Krafft point and enhance the soap solubility in water. With increasing the tetraalkylammonium ionic size, the degree of "salting-in" of soaps in water increases. However, solubility of pure tetraalkylammonium bromide in water decreases as the length of the alkyl chains increases. Furthermore, in the ternary water-tetrapentylammonium bromide (TPeAB)-sodium myristate (NaMy) system, we observed an upper cloud point phenomenon, which greatly shrinks the 1-phase micellar solution region in the phase diagram. This miscibility gap, together with the organic salt solubility limitation, restricts the use of tetraalkylammonium bromides with alkyl chains longer than 4 carbon atoms as effective soap solubility enhancement electrolytes. We also found that for sodium soap with a longer hydrocarbon chain, more tetrabutylammonium salt is required to reduce the soap Krafft point to room temperature.     

Emulsion polymerization. I. Recalculation and extension of the Smith-Ewart theory

The most important assumptions underlying the Smith-Ewart theory are that the locus of chain propagation is the monomer-swollen latex particle, polymeric chains are initiated by radicals entering from the water phase into the particles, chain termination is an instantaneous reaction between two radicals within one particle, and particles are nucleated by radicals absorbed into monomer-swollen soap micelles. Right or wrong, these and other assumptions used by Smith and Ewart are retained in this paper. The newly derived and experimentally verifiable equations contain only such parameters which can be determined by experiments not involving emulsion polymerization. The proportionality constant between the particle number and the appropriate powers of soap and initiator concentrations is defined in terms of these independent parameters. Absolute rate equations are presented for the intervals before and after the completion of particle nucleation. To calculate these rates it is not necessary to have prior knowledge of the experimental particle number. The conversion at which particle nucleation is complete is calculated. The molecular weight is defined in terms of independent parameters. Predictions are made for the particle size distribution. It is shown that the validity of the theory is confined to specifiable intervals of conversion, to a certain range of monomer/water ratio, and to soap concentrations whose upper and lower limits are given.     

An HPLC Method for the Analysis of Glycerol and Other Glycols in Soap

Abstract

A method has been developed to separate and quantitate glycerol (1,2,3 Propanetriol) in soap via HPLC using refractive index detection. The method has good reproducibility and accuracy, and can be achieved in 30 minutes or less, including sample preparation, and compares well with standard methods. The detection of other glycols common to the soap and cosmetics industry is also described.     

金属皂非水体系的研究 Ⅰ. 一元油酸钴皂有机溶液的流变性质

本文研究了一元油酸钴皂的苯与庚烷溶液的流变性质。皂溶液粘度随放置时间而增大, 并趋于稳定的平衡值。稀的钴皂溶液已经表现出显著的非牛顿性。钴皂的增稠作用是皂分子因配位结合形成大分子链的结果。添加剂含有与钴原子配位结合强的基团时, 使皂溶液粘度降至与溶剂相近。     

Mechanism for defoaming by oils and calcium soap in aqueous systems

The effect of oils, hardness, and calcium soap on foam stability of aqueous solutions of commercial surfactants was investigated. For conditions where negligible calcium soap was formed, stability of foams made with 0.1 wt% solutions of a seven-EO alcohol ethoxylate containing dispersed drops of n-hexadecane, triolein, or mixtures of these oils with small amounts of oleic acid could be understood in terms of entry, spreading, and bridging coefficients, i.e., ESB analysis. However, foams made from solutions containing 0.01 wt% of three-EO alcohol ethoxysulfate sodium salt and the same dispersed oils were frequently more stable than expected based on ESB analysis, reflecting that repulsion due to overlap of electrical double layers in the asymmetric oil-water-air film made oil entry into the air-water interface more difficult than the theory predicts. When calcium soap was formed in situ by the reaction of fatty acids in the oil with calcium, solid soap particles were observed at the surfaces of the oil drops. The combination of oil and calcium soap produced a synergistic effect facilitating the well-known bridging instability of foam films or Plateau borders and producing a substantial defoaming effect. A possible mechanism of instability involving increases in disjoining pressure at locations where small soap particles approach the air-water interface is discussed. For both surfactants with the triolein-oleic acid mixtures, calculated entry and bridging coefficients for conditions when calcium soap formed were positive shortly after foam generation but negative at equilibrium. These results are consistent with the experimental observation that most defoaming action occurred shortly after foam generation rather than at later times.     

Improved sample treatment for the determination of insoluble soap in sewage sludge samples by liquid chromatography with fluorescence detection

A new selective and sensitive method for the determination of insoluble fatty acid salts (soap) in sewage sludge samples is proposed. The method involves a clean up of sample with petroleum ether, the conversion of calcium and magnesium insoluble salts into soluble potassium salts, potassium salts extraction with methanol, and a derivatization procedure previous to the liquid chromatography with fluorescence detection (LC-FLD) analysis. Three different extraction techniques (Soxhlet, microwave-assisted extraction and ultrasounds) were compared and microwave-assisted extraction (MAE) was selected as appropriate for our purpose. This allowed to reduce the extraction time and solvent waste (50 mL of methanol in contrast with 250 mL for Soxhlet procedure). The absence of matrix effect was demonstrated with two standards (C_13:0 and C_17:0) that are not commercials and neither of them has been detected in sewage sludge samples. Therefore, it was possible to evaluate the matrix effect since both standards have similar environmental behaviour (adsorption and precipitation) to commercial soaps (C_10:0-C_18:0). The method was successfully applied to samples from different sources and consequently, with different composition.     

The Potentiometric Titration of Soaps Using a Liquid Membrane Electrode

Abstract

A liquid membrane soap or surfactant sensitive electrode capable of working throughout the pH range 1–13 has been developed. The active substance of the electrode is the ion-association complex of dodecylbenzene sulphonate with bisdimethylglyoxime-o-phenanthroline-cobaltate(III). The electrode enables soap or surfactant titration depending on the pH.     

(Series Editor) Transform Techniques in Chemistry,P.R. Griffiths,D. Hercules (Eds.), in: Modern Analytical Chemistry Series,Plenum, New York,NY (1978), 385 pp. $47.40

Concentration potentials in zinc sulphate, copper sulphate, nickel sulphate and cobalt sulphate solutions across liquid membranes based on myristates and laurates of zinc, copper, nickel and cobalt and caprate and caprylate of copper have been studied in concentration cells in which the liquid membrane separates the two solutions of the same electrolyte. The behaviour of the cell with heavy metal soap liquid ion-exchange membranes becomes more and more nernstian as the number of carbon atoms in the hydrocarbon chain of the fatty acid soap increases. Concentration potential values with copper, zinc, nickel or cobalt soap follow the order of their insolubility in water. The failure to record the theoretical potentials as calculated by Nernst's equation has been explained by considering the transport of water across organic phase by hydrated ions and the dissolution of heavy metal soaps in aqueous solutions. Liquid membranes based on heavy metal myristate soaps when used in concentration cells could measure the activities of zinc, copper, nickel and cobalt ions in the concentration range of 10^?4–10^?1M.     

Polymerisation of liquid crystalline phases in binary surfactant/water systems

The polymerisation of a polymerisable fatty acid surfactant (sodium 10-undecenoate) has been studied in both its self-assembled and non self-assembled forms. Polymerisation in non self-assembled solution was achieved to near completion. The polymerisation produces a surface active polymer. The self-assembling behaviour of this pre-polymerised form differs markedly from that observed for the monomeric surfactant [1]. A lamellar phase only is formed in the polymeric phase diagram with no hexagonal or lamellar gel phases being observed. Polymerisation in the different self-assembled forms of sodium 10-undecenoate reached a limit of approximately 30% only, i.e., the surfactant aggregates act to inhibit the polymerisation. The nature of the hydrocarbon chain was found to play a critical role in determining the effect that polymerisation had on the underlying geometry of the surfactant molecules. When the chains are in a fluid-like state (as for the micellar and hexagonal phases) the original monomeric matrix remains largely unchanged. Whereas partial polymerisation of the lamellar gel phase results in a phase transformation.In addition the hydrolysis of the fatty acid soap at low concentrations (close to the critical micelle concentration) has been investigated. Hydrolysis was shown to produce both the parent fatty acid and an acid soap dimer. The presence of these species greatly affects the solution behaviour in this region of the phase diagram shifting the critical micelle concentration to very high concentrations of sodium 10-undecenoate (ca. 0.4 M).     

Effect of surface mobility on the uniformity of a thin film under a bubble

The shape of a soap bubble placed on a solid surface is familiar to everyone-a thin hemispherical dome that thickens near the solid surface. This structure is stabilized by the balance between the film's elasticity, provided by surfactant molecules, and the pressure inside the bubble. However, there is also a soap film on the flat solid surface that has been mostly ignored in previous studies; its thickness is typically assumed to be constant or varying monotonically. In this letter, for the first time, we show that the thickness of this film is not always monotonic. Depending on the surfactant type, it can exhibit a significant dip, similar to marginal pinching. This finding has a significant influence in numerous applications in which solid/foam interactions are important, such as oil extraction or foam-based drug delivery.     

Emulsion polymerization. II. Review of experimental data in the context of the revised Smith-Ewart theory

Tables are presented for convenient calculation of the basic parameters of the revised Smith-Ewart theory. For the methyl methacrylate (MMA)/sodium lauryl sulfate (SLS)/K₂S₂O₈, and for the styrene/SLS/K₂S₂O₈ reaction mixtures parameters are presented from which the absolute values of the following quantities can be conveniently calculated for any temperature, soap, and initiator concentration: particle number, particle radius, conversion where particle nucleation stops, rate and molecular weight in interval II, the interval after completion of particle nucleation and before the disappearance of monomer droplets. The theoretical predictions are compared to new experimental data and to those from the literature. The available data confirm the theoretical prediction that particle nucleation stops after a very small amount of polymer is formed, of the order of 0.01 cc. polymer/cc. water in most recipes. The theory and experiments are in good qualitative agreement for the conversion rate prior to completion of particle formation: the conversion rate rises with time and, when particle nucleation stops, it levels off. Excellent quantitative agreement can be obtained between theoretical and experimental particle size values. In the experiments of this laboratory the SLS concentration was varied 60-fold, the K₂S₂O₈ concentration was varied 140-fold and the difference between theoretical and experimental poly(MMA) particle radii was always less than about 20%. Similar good agreement was obtained for polystyrene over the temperature range 30–90°C. Some polystyrene data from the literature with carboxylic soaps give just as good fit as the data with SLS of this laboratory. The predicted proportionality between particle number and the product of 0.6 power of soap concentration and of 0.4 power of initiator concentration was observed for several monomers. The theoretical predictions for the rate and molecular weight obtained in interval II are valid only for relatively low initiator and high soap recipes. For recipes for MMA and styrene the rate data are in good agreement with those calculated from the theory. The theory also correctly predicts the order of magnitude of the experimental molecular weights. For several monomers the rate and molecular weight vary with initiator and soap concentrations in a manner close to theoretical predictions.