Fig. 5 presents the SEM images of a liquid nitrogen fractured
surface of the CG-g-PVA with different CG:PVA ratios. At a low amount of CG in the blend, the CG was chemically compatible to
PVA, and the hydroxyl groups from the PVA and CG were essentially
within the hydrogen bond network. Therefore it was hard to connect
the hydroxyl groups from both components by building new
hydrogen bonds and chemically bonding them. This resulted in an
inferior interfacial interaction of the polymer hydrogel (Pas¸ cal˘au
et al., 2012). When the CG in the graft copolymer increased, a phase
separation of the polymer hydrogel occurred as seen in the SEM.
These results were a reflection of the tensile strength.