Mechanical properties of Polyamide 12 after exposed to biodiesel

In this study, the mechanical properties of polyamide 12 (PA12) exposed to two types of fuel, B5 - market standard diesel with 5% biodiesel and B100 - pure biodiesel were investigated. The PA12 analyzed was a commercial grade VESTAMID (R) X7393, used for fuel hoses manufacturing. Samples for tensile and impact tests, obtained by injection molding, were immersed in two types of fuel (B5 and B100) contained in opaque vessels. Some vessels were stored at 100 degrees C in an oven and the others were stored at room temperature. After remained immersed for a set time (1000, 3000 and 5000hours), the samples were taken out of the vessels and characterized by mechanical properties (tensile and impact strength). PA12 samples aged in B5 and B100 at 100 degrees C presented a decrease in elongation at break and impact strength and an increase in Young modulus with increasing aging time. The tensile strength of PA12 aged in B5 and B100 decreased and increase, respectively, with increasing aging time. B5 was more aggressive than B100 for PA12. PA12 samples aged in B5 and B100 at room temperature presented a decrease in tensile strength with increasing aging time. From 3000 hours of aging, a decrease in Young modulus and an increase in impact strength was observed. This behavior was more pronounced for samples aged in B100.