The importance of hydrodynamics and mechanical action in fabric washing

  • Jo Douglas

Student thesis: Doctoral ThesisPhD


Washing fabrics is a ubiquitous process that has been found to have been common even in early civilisations. The process can be performed by hand or with the aid of a washing machine, giving rise to a wide range of wash conditions. Although this process is very common the mechanisms involved are poorly understood, but are thought to involve chemical, mechanical and hydrodynamic inputs. The main aim of this project is to test whether these inputs can be used to improve the efficiency of cleaning fabrics at lower temperatures, and to better understand the mechanisms involved in these individual actions.The cleaning of polyester and cotton fabrics soiled with artificial sebum has been investigated with 20 °C, 40 °C and 60 °C wash solutions. Fabrics have been cleaned with a model surfactant system consisting of Linear Alkylbenzene Sulfonate (LAS) at 0.1 times and twice the Critical Micelle Concentration (CMC), and results compared to water. Bespoke rigs to simulate rubbing, stretching and flow have been optimised and methods developed for cleaning and analysis of fabrics. Cleaning has been characterised by mass change, colour change and resistance change. Mass change gives an indication of the overall removal, whereas colour gives an analytical measure of the difference in the appearance of the fabrics, and change in resistance to flow of water through the fabric shows how much sebum has been removed from the pores. Additional analysis has been completed on the fabrics including FTIR, mass per unit area, SEM and zeta potential measurements. Removal was highest when the fabric was washed at 60 °C with a high concentration of surfactant. Soaking alone removed some of the mass, but this increased when mechanical action was also used. Of the mechanical actions, rubbing was found to be the most effective under most conditions. On the whole, cleaning was more effective at 40 °C than 20 °C, and a higher concentration of surfactant aided removal of soil to a greater extent that at a lower concentration or with water alone. However, some exceptions to these trends have been identified.
Date of Award27 Jun 2017
Original languageEnglish
Awarding Institution
  • University of Bath
SupervisorMichael Bird (Supervisor) & John Chew (Supervisor)

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