Chemistry Reference
In-Depth Information
8.3.3.4 Effect of TO Content on Mechanical Properties
The changes in tensile and flexural strength and modulus of the matrices
obtained from DCPD-UPR-TO polymers with different TO contents are il-
lustrated in Figure 8.18. All these properties decreased as the TO content
increased, indicating a decrease in stiffness for all DCPD-UPR-TO polymer
matrices. This is mainly due to the decrease in cross-link density. Interest-
ingly, the decrease in stiffness showed two distinct regions: at TO contents
below 10 wt%, the stiffness of DCPD-UPR-TO bio-materials gradually de-
creased; at TO contents above 10 wt%, the stiffness decreased rapidly. This
phenomenon can be attributed to the phase separation, as indicated in the
SEM images (Figure 8.15). As mentioned above, the introduction of a second
rubber-like, oil-rich phase would sacrifice the stiffness of a polymer matrix.
Compared to the neat DCPD-UPR matrix, the DCPD-UPR-TO10 matrix
demonstrated decreases of 5.3% and 18.8% in tensile and flexural strength,
and 19.3% and 16% in tensile and flexural modulus, respectively.
The changes in impact strength and tensile failure strain of the DCPD-
UPR-TO polymer matrices are shown in Figure 8.19. All these properties
increased as the TO content increased suggesting an increase of toughness
for all the DCPD-UPR-TO polymer matrices. Similar to the stiffness shown
above, the increase of toughness could be divided into two distinct regions,
which was also caused by the effect of phase separation. Compared to the
neat DCPD-UPR matrix, the DCPD-UPR-TO10 matrix showed increases of
72.5 and 91.3% in impact strength and tensile failure strain, while the in-
creases for the DCPD-UPR-TO20 matrix were 373 and 875%, respectively.
Hence, the toughness of the DCPD-UPR matrix was greatly improved by the
chemical approach we employed. Such a large improvement in toughness is
Figure 8.18 Tensile and flexural properties. (a) Strength and (b) modulus of the
polymer matrices obtained from DCPD-UPR-TO polymers with different
TO contents.
