Brown Spider Venom: The Identification and Biotechnological Potential of Venom Toxins

Abstract

The length change-sorbed water isotherm of glass-fiber reinforced polyester (GRP) composite at 23°C indicates that for equilibrium water contents higher than a certain critical value a marked decrease in the relative rate of swelling strain per unit rate of sorbed water occurs in both the control and the weathered material. The change in rate is attributed to the micro-heterogeneity of the matrix resin, which consists of a mixture of dense microgel particles (highly crosslinked resin islands) embedded in a less dense continuous resin phase (crosslinked to a lesser degree). At equilibrium concentrations lower than the critical value, most or possibly ail of the sorbed water is contained in the less dense phase of the resin, which is more easily penetrated by the water. As this phase is less restrained because there are fewer crosslinks, it swells to a greater extent than the microgel phase, which absorbs most of the water above the critical concentration. The amount of linear swelling in the weathered sheet is lower than that of the control sheet. Weathering also results in lower rates of swelling below the critical value of equilibrium sorbed water content, but induces considerably higher rates above that value.