The effect of addition of sodium hexadecyl sulfate on the performance properties of lauramidopropyl betaine

Palm fatty acid distillates can be used to produce fatty alcohol sulphates. The sodium hexadecyl sulphate (SHS) of the C16 fatty acid thus formed has a high Krafft point which limits its use in applications. Here we propose the use of C16 sulphate mixed with the amphoteric lauramidopropyl betaine (LAPB). The solubility of SHS in LAPB was determined and mixtures of the two were prepared to the extent of their solubility. The interfacial properties of the surfactant mixtures were investigated. The CMC of the surfactant mixtures was determined using dye solubilisation. The performance properties of the mixtures, such as foaming and viscosity, were analysed. It was concluded that the addition of even small amounts of SHS to LAPB causes a significant change in its CMC, although the performance properties of LAPB in terms of foaming and viscosity are maintained.