The mechanical properties of the PVA/PAA blend films were investigated
using a universal testing machine; the results are depicted
in Fig. 9. The tensile strength and elongation at break of pure
PVA are 5.7 MPa and 200%, respectively. For the blends, the tensile
strength increases with increasing PAA content, whereas the
elongation at break decreases. Related to the crosslinking and strong intermolecular interactions between PVA and PAA, the polymer chains become more tightly packed and increasingly rigid with increasing PAA content.18 Therefore, the blend films exhibit decreased ductility and become brittle as a result of the extensive crosslinking.24