Influence of the Physical and Chemical Properties of Composite Insoles on the Microclimate in Protective Footwear

The objective of the paper was to evaluate the influence of the physical and chemical prop erties of composite insoles on the microclimate in protective footwear under conditions of hard physical work. The study used the sorption kinetics of composite insoles using artificial sweat with acidic and alkaline pH, the porosity of the composite structure, and measurement of the microclimate inside the footwear in a test involving human subjects under laboratory conditions on a treadmill. The results revealed that sorption kinetics largely depend on sweat pH – sorption is slower at alkaline pH (less effective moisture transport across the insole) than at acidic pH (more effective moisture transport). Strong correlations were found between the sorption parameters of the composite insole at alkaline pH and the porosity parameters of its structure. The microclimate measurements showed optimum temperature and humidity levels inside the footwear, which remained within the thresholds of comfort of use defined in the literature. It was found that composite insoles containing a polycarbonate melt-blown nonwoven may be recommended in particular for non-permeable protective footwear in conditions of very intensive physical work, which is accompanied by a shift in pH from acidic to alkaline.