Radiotracer detergency testing in a horizontal-axis washing machine

Proposed regulations by the U.S. Department of Energy have spurred development of energy-efficient washing machines that utilize less water and operate with lower energy requirements than conventional machines. As a result, major changes in washing machine design are required. Among expected changes are increased use of a horizontal-axis wash tub, an increase in fabric-to-wash liquor ratio, greater surfactant concentration in the wash water, and reduced average washing temperatures. As a result, surfactants used in future detergent formulations will be required to clean effectively in this new regime while producing minimal foam. Detergency test methods utilizing radiotracer techniques have been developed to study the detergency process in energy-efficient washing machines. Detergency and redeposition of radiolabeled oily soils can be determined in a full-size horizontal-axis washing machine through scintillation counting of wash and rinse water samples. Measurements can be made after each wash process step and combined to determine total cycle detergency. This is a distinct advantage over conventional reflectance detergency methods where only total detergency at the end of the entire washing and rinsing process can be conveniently measured. Also, in contrast to indirect reflectance methods, measurements of absolute soil removal are obtained with the radiotracer method. In this study, soil redeposition was determined by measuring residual radioactivity on fabric swatches and then performing a material balance on the oily soil.     

Clearning performance and foaming properties of lauroylamidopropylbetaine/nonionics mixed systems

Lauroylamidopropylbetaine (LPB) has good cleaning and foaming performance with excellent low skin irritation. We have investigated the relationship between cleaning performance and foaming properties of aqueous solutions containing binary and ternary LPB/nonionic surfactant systems. Foaming properties were evaluated by observing dynamic surface tension and aqueous core thickness of a vertical foam film measured by Fourier transform infrared spectroscopy. The LPB/lauroyldiethanolamide (LDE) system has a positive synergistic effect on cleaning performance and foam stability, estimated from the grease removal test and dishwashing test for a light-duty detergent. However, this system shows very poor initial foam performance in both the sponge test and Ross-Miles foam test. This disadvantage of the LPB/LDE system was improved using C12En (polyoxyethylene dodecyl ethers). Addition of C12En promoted dynamic surface tension lowering, indicating an improvement in the initial foaming performance, while maintaining cleaning performance and foam durability. Thus, the LPB/LDE/C12En ternary system has an excellent cleaning and foam performance as a light-duty liquid detergent.     

Ester alkoxylation technology

Conventional ethyoxylation technologies, when used on fatty methyl esters, produce poor yields as well as flat ethoxymer distributions. Peaking ethoxylation catalysts have been successful in efficient conversion of methyl esters into the ethoxylates possessing peaked ethoxymer distribution. Surfactant performance of methyl ester ethoxylates was evaluated. Results generally show these to behave similarly to alcohol ethoxylates, with the exception of exhibiting a lower foam profile. This ester ethoxylation technology has been successful in ethoxylating esters of varying steric environments. Triglyceride ethoxylates have been partially saponified as well as glucaminolyzed to produce mild surfactant blends. Samuel Rosen Memorial Award Presentation, at the 90^th American Oil Chemists' Society Annual Meeting and Expo, Orlando, FL, May 1999. The author dedicates this paper to the memory of the late Professor William H. Wade of the University of Texas, Austin, TX.     

Impact of composition on the performance of sodium linear alkylbenzenesulfonate (NaLAS)

Like other commercial surfactants, commercial linear alkylbenzenesulfonate is not a single compound but a mixture of components. This mixture comprises different carbonchain homologs, different phenyl isomers, and, in addition, the manufacturing co-product, dialkyltetralin sulfonate. Current manufacturing technology makes it possible to easily vary the average carbon chainlength. On the other hand, the phenyl isomer distribution and dialkyltetralin sulfonate content can be changed only within a certain range. Each of these variations in composition affects performance. This study reports on the effect of commercial alkylbenzenesulfonate composition on surface tension, solubility, viscosity, foam stability, and detergency. The study shows that average carbon chainlength affects all performance properties. Phenyl isomer distribution and dialkyltetralin sulfonate content affect only solubility and viscosity. Presented May 1, 1996, at the Annual Meeting of the American Oil Chemists’ Society, Indianapolis, Indiana.     

四冲程摩托车发动机油行车试验研究

本文介绍了几种商品四冲摩托车专用润滑油在嘉陵ＪＨ１２５Ｄ型摩托车上的行车试验研究。试验结果表明,运用合理的添加剂配方技术,提高润滑油的抗氧化能力是改善四冲程发动机油清净性和抗磨性的关键。     

Fatty Acid soil detergency performance of poly(sodium α-hydroxyacrylate)

Effects and properties of poly(sodium α-hydroxyacrylate) (PHA) on removal of stearic and oleic acids from cellulosic filter paper under various wash conditions were evaluated and compared with those of sodium dodecyl sulfate (SDS) by using differential scanning calorimetry. PHA had a much greater effect on the removal of stearic and oleic acids than SDS under the same washing conditions. PHA produces complexes with fatty acids on filter paper during the washing process, and in DSC these complexes have endothermic peaks at temperatures higher than the melting point of the fatty acids. The complexes are formed at temperatures both below and above the melting point of the fatty acid and are removed completely from filter paper by rinsing. The conditions of temperature, time, and PHA concentration during washing all affected the formation of the complex and the removal of fatty acid. Whether the fatty acid chain was saturated or not did not affect the formation of a complex.     

Properties of Didecyldimethylammonium Formate and Sodium Fatty Alcohol Ether Carboxylate Mixed Systems

The surface activities and application properties of didecyldimethylammonium formate (DDAF) and sodium fatty alcohol ether carboxylate (AEC-9Na) mixed systems were measured. The results showed that the critical micelle concentration and surface tension of mixed systems have lower values than that of a single surfactant solution, which is attributed to the synergism of DDAF and AEC-9Na. It was found that the emulsifying properties for kerosene and wetting properties of the mixed systems were also better than single component surfactants. In addition, the mixed systems of AEC-9Na (16 wt%) with DDAF showed both better detergency and excellent antibacterial properties.     

The effect of micellar lifetime on the rate of solubilization and detergency in sodium dodecyl sulfate solutions

The slow relaxation time (τ₂) of sodium dodecyl sulfate (SDS) micelles, measured by the pressure-jump technique, was maximum at 200 mM concentration at 25°C, indicating that the most stable micelles are formed at this concentration. This is presumably related to the optimum molecular packing in the micelle. The rate of solubilization of benzene and Orange OT dye into SDS solutions was also maximum at 200 mM concentration. The results are explained as follows: The distance between micelles (i.e., intermicellar distance) decreases as the surfactant concentration (or the number of micelles) increases, resulting in a stronger electric repulsion between micelles. Therefore, the micelles become more rigid, due to the compressive force of intermicellar repulsion, as the concentration increases up to 200 mM SDS. With further increase in the SDS concentration, the micellar shape changes from spherical to cylindrical to accommodate more surfactant molecules in the solution and to minimize the free energy of the system. The interior of the tightly packed micelles is more hydrophobic than that of loosely packed micelles and, therefore, the tightly packed micelles induce rapid solubilization of nonpolar molecules (e.g., benzene, Orange OT) into these micelles.     

Surface Activity and Performance Properties of Gemini Salts of Linear Alkylbenzene Sulfonate in Aqueous Solution

Gemini salts of linear alkylbenzene sulfonate (LABS) were prepared by neutralization of sulfonic acid with a series of low-molecular-weight diamines in aqueous solution. The equilibrium surface activity of Gemini salts of LABS was determined by measuring the surface tension as a function of surfactant concentration to determine the critical micelle concentration (CMC), surface tension at the CMC (γ_CMC), and the area per molecule at the air-water interface (Ų). Electrical conductivity was measured as a function of surfactant concentration to determine the CMC and counterion binding. Dynamic surface tension was measured using a bubble pressure tensiometer to infer the rate at which the surfactant migrates to the air-water interface. Equilibrium interfacial tension against mineral oil was measured using a spinning drop tensiometer. Dynamic interfacial tension was measured using a drop volume tensiometer. The surface tension, CMC, and interfacial tension of Gemini salts of LABS decreased compared to monovalent organic and inorganic salts. The CMC decreases with increasing molecular weight of the diamine spacer group. Dynamic surface and interfacial tension of Gemini salts of LABS are lower than monovalent salts. The foam volume of Gemini salts of LABS was determined using a high shear blender test. The foam volume of Gemini salts of LABS is lower than monovalent salts and depends on the size of the spacer group. Hard-surface cleaning was measured using artificial soil applied to white Formica tiles. Soil removal was determined by optical reflectance as a function of abrasion cycles. Gemini salts of LABS show reduced hard-surface cleaning performance compared to monovalent salts. Detergency of different types of soils on cotton and polyester/cotton fabric was determined by optical reflectance measurements. Gemini salts of LABS show improved cleaning performance compared to monovalent salts. Cleaning performance increases with increasing molecular weight of the diamine spacer group. In situ neutralization of LABS with organic diamines is a simple and efficient way to prepare anionic Gemini surfactants for industrial scale applications.