A MODEL OF WATER-VAPOR TRANSMISSION IN HYDROCOLLOID WOUND DRESSINGS

Hydrocolloid wound dressings (HWDs) are used extensively in the treatm ent of skin trauma. They have laminated structures consisting of an in ner (hydrocolloid) layer which absorbs wound exudate and an outer laye r (typically polyurethane) which acts as a rate limiting barrier and p rovides mechanical strength. Water vapour transmission is an important performance parameter and for HWDs the transport process is complicat ed by the swelling of the hydrocolloid layer. A model was developed to predict this process and takes into account concentration-dependent d iffusivity and solubility, moving boundary and convection effects. A f inite difference solution to the model was obtained and validated by e xperiments on a widely used HWD, Duoderm CGF. A parametric study was c arried out and it was found that the most sensitive parameters were th e diffusivity and solubility of the hydrocolloid layer. It is expected that the model developed and the results obtained will further the kn owledge of water vapour transport within wound dressings and will assi st in material selection and design of new dressings.