Mechanical behavior of epoxy resin with graphite additive subjected to water absorption

Epoxy resin-based composites find extensive applications across various industries due to their unique mechanical properties. They are commonly used in gas and petrochemical industries for pipes and fittings in transmission lines. The primary objective of this study is to investigate changes in the mechanical properties of epoxy resin-based composites under different environmental moisture conditions. To achieve this, epoxy resin with varying weight percentages of graphite additive (0, 5, 10, 15, and 25 wt%) was used. The water absorption characteristics of the specimens were assessed by immersing samples in potable water (PW), distilled water (DW), a 10 vol% alkaline solution (NaCl), and a 10 vol% acidic solution (HCl), following ASTM standards. Both dry and wet samples were examined for various mechanical strengths. The results indicate that, for all weight percentages of graphite additive, water absorption follows the increasing order: NaCl < PW < DW < HCl, as compared to the blank resin case. In terms of mechanical testing, increasing the weight percentage of graphite additive resulted in a 24 % decrease in Barcol hardness and a 39 % decrease in impact strength, while the hot deflection temperature (HDT) increased for 5 wt% and showed no significant effects for the other cases.