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These compounds with various connecting groups between the two lipophilic groups were prepared by the reaction of glycol diglycidyl ethers with long-chain alcohols, followed by sulfation with chlorosulfonic acid or with a mixture of chlorosulfonic acid and acetic acid. The Krafft point of all these new amphipathic compounds was below 0~ and they had good water solubility. These compounds were superior in surface active properties to general anionic surfactants with one lipophilic chain and one hydrophilic group, such as sodium dodecylsulfate. The effect of the structure of the connecting group on CMC, YCMC, foaming properties and wetting ability was investigated. They also showed excellent lime-soap dispersing ability.

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Novel surfactants with two long-chain alkyl groups and two sulfonate groups were synthesized by reactions of oligo (ethyleneglycol) diglycidyl ethers or bis (2, 3-epoxypropyl) ether with long-chain fatty alcohols, followed by reaction with propanesultone. The double-chain compounds showed good water solubility, excellent micelle forming properties and the higher ability to lower surface tension than general sulfonate type of single-chain surfactants. The effects of structural factors of these surfactants on surface active properties are discussed. These compounds were soluble and showed surface active properties in hard water above 5555 ppm of total hardness as CaCO3. They had better lime-soap dispersing ability than sodium 1-dodecene sulfate or sodium 1-dodecane sulfonate. Table-3 Foaming properties and LSDR of compounds 3a-g at 20•Ž and sodium dodecyl sulfonate at 45•Ž.

Bis(sulfonate} types of amphipathic compounds with three long-chain alkyl groups were prepared by the reaction of N-(long-chain acyl}diethanolamine diglycidyl ethers with long-chain fatty alcohols, followed by the reaction with propanesultone. The diglycidyl ethers were easily obtained from the corresponding N-acyldiethanolandnes and epichlorohydrin in the presence of a phase-transfer catalyst. The same types of compounds with two longchain alkyl groups were also prepared from Nacetyldiethanolamine according to similar procedures. All these new double-or triple-chain surfactants were soluble in water and showed much better micelle forming and ability to lower surface tension than general types of single-chain surfactants with one sulfonate group. The critical micelle concentration (CMC) and ~' CMC values of the triple-chain compounds were still much smaller than those of the corresponding double-chain compounds with two common alkyl groups. The efficiency of adsorption at the water/air interface (pC20) of these surfactants was very high. Their foaming properties, wetting ability toward a felt chip, and lime-soap dispersing ability were measured.

Open cell foams with auxeticity and modulus 5 times larger than the stiffest auxetic polymeric open cell foam featured in scientific literature are developed in this paper by using vacuum bags and autoclave following a thermoforming process. The resulting foam is transverse isotropic with microstructures exhibiting elongated semi-reticulated configurations, and contains a plane in which the auxetic behavior is evident. Tensile and compression quasi-static tests were carried out on samples cut along different directions and with different thicknesses. Foams have been also subjected to tensile training at different maximum strains to assess their mechanical performance. The tensile modulus and Poisson's ratio values of the auxetic foams produced in this work can reach 25MPa and -0.4 in one plane and can feature a negative Poisson's ratio up to -1.3 for thinner specimens. Smaller thicknesses and higher tensile training strains can also reduce the stiffness but enhance the auxeticity of this porous material.

The Nonlinear Output Frequency Response Functions (NOFRFs) are a concept which provides a new extension of the well-known concept of the Frequency Response Function (FRF) of linear systems to the nonlinear case. The present study introduces a NOFRFs based approach for the analysis of nonlinear systems in the frequency domain. It is well known that a nonlinear system can, under rather general conditions, be represented by a polynomial type Nonlinear Auto Regressive with eXogenous input (NARX) model. From the NARX model of a nonlinear system under study, the NOFRFs based approach for the frequency analysis of nonlinear systems involves solving a set of linear difference equations known as the Associated Linear Equations (ALEs) to determine the system nonlinear output responses and then the NOFRFs of the system up to an arbitrary order of nonlinearity of interests. The results enable a representation of the frequency domain characteristics of nonlinear systems by means of a series of Bode diagram like plots that can be used for nonlinear system frequency analyses for various purposes including, for example, condition monitoring, fault diagnosis, and nonlinear modal analysis.

Unusual behaviour in which the critical micelle concentration (CMC) values in water for a homologous series of the title amphiphiles increased with an increase in the number of carbons of the lipophilic alkyl chains was observed when these data were obtained by the common surface tension method using a Wilhelmy tensiometer.