Mechanical Behavior and Surface Properties of Silicone and PVC Gastric Tubes Under Controlled pH Conditions

In this study, the mechanical behavior, wettability, and surface free energy (SFE) of gastric feeding tubes made of silicone and poly(vinyl chloride) (PVC) were investigated under controlled pH conditions and varying exposure times. Wettability was evaluated using contact angle measurements, and SFE was determined using the Owens–Wendt–Rabel–Kaelble (OWRK), Wu, and van Oss–Chaudhury–Good (vOCG) approaches. Mechanical behavior was analyzed by static tensile testing and stopper pull-off tests. The results showed distinct differences between the materials. PVC tended to exhibit a more stable mechanical response under the tested conditions, whereas silicone exhibited lower stiffness and greater sensitivity to environmental exposure. Surface analysis indicated that PVC maintained relatively stable SFE values (~41–45 mJ/m2 according to the OWRK model), whereas silicone exhibited more pronounced variations (~19–34 mJ/m2), primarily associated with changes in polar surface components. These modifications became more pronounced with prolonged incubation and occurred alongside changes observed in mechanical response. The findings provide insight into the long-term performance of gastric feeding tube materials and highlight the importance of considering both mechanical and surface properties during material evaluation.