Mechanical Characteristics of PVA/STMP Hydrogel in Tensile and Unconfined Compression

Hydrogels based on Poly(vinyl alcohol) (PVA) were synthesized using the combining method of chemical agent and freezing-thawing cycle. Sodium Trimetaphosphate (STMP) is a kind of crosslinking agent in this reaction. The resulting hydrogels were characterized in terms of tensile properties and compression stress-strain testing. The influences of STMP and water content on mechanical properties of hydrogels were investigated. It is suggested that PVA hydrogel has excellent tensile strength, higher elongation at break and viscoelastic materials’ stress-strain curve. Tensile strength of specimens without STMP increases from 4 to 6.8 MPa, as well as elongation increase from 300% to 458%, respectively. When the strain changes from 10% to 50%, tangent compressive modulus dramatically increases from 0.58 to 9.9 MPa for hydrogels with 80wt % water and 0.41 to 5.4 MPa for 85wt % water. Meanwhile, the addition of STMP can further improve the mechanical properties of PVA hydrogel.