EFFECTS OF PLASTICIZERS ON THE MECHANICAL-PROPERTIES OF POLY(VINYL CHLORIDE) MEMBRANES FOR ELECTRODES AND BIOSENSORS

In electrodes and biosensors poly(vinyl chloride) (PVC) membranes were plasticized to 200 parts per hundred resin, independent of plasticize r specie. Puncture tests quantified five mechanical properties for at least eight levels of seven plasticizers. Using Citroflex B-6 at a phr ratio of 0.31, the strength and secant stiffness peaked at 9.63 N and 1250 N m(-1), respectively. At a phr ratio of 0.6 the toughness peake d at 48 N mm. These three properties decreased at higher phr ratios fo r all plasticizers. Tangent stiffnesses were generally 1.7 times secan t stiffnesses. For all plasticizers, ductility increased to a constant value of 15 mm at a phr ratio of two. The molecular structures of the plasticizers influenced the mechanical properties. For a given phr ra tio, plasticizers having lower hydrodynamic volumes increased the stre ngths, stiffnesses, and toughnesses of the membranes. Compared to prio r dielectric testing, the strength, toughness, and stiffness increased as the ionic resistivity increased. In electrodes and biosensors phr ratios should be reduced to a minimum of one. (C) 1997 Elsevier Scienc e Ltd.