In situ formed internal water channels improving water swelling and mechanical properties of water swellable rubber composites

In this study, electrospun nanofibers of poly (vinyl alcohol) (PVA) and styrene–butadiene–styrene triblock copolymer (SBS) were employed in conventional water-swellable rubber (WSR) to design WSR composites with improved water swelling and mechanical properties. With the introduction of PVA nanofibers, considerable improvement in elasticity, strength, and water-swelling behavior was observed. After immersion, PVA nanofibers dissolved within the composite to in situ form water channels to connect isolated super-absorbent polymers (SAPs). Those water channels led to an increase in water uptake by the WSR composite. Furthermore, the secondary water-swelling behaviors of the WSR composite showed a remarkable increase in swelling rate as well as in mechanical properties. The addition of SBS nanofibers had a marked impact on the mechanical properties of the WSR composite. Their roles became more pronounced after water immersion. The proposed enhancement mechanism is also discussed.