Chemistry Reference
In-Depth Information
Figure 8.14
Impact strength of the four TO-based resins with different styrene
concentrations.
the best stiffness in the four resins, although it had a moderate cross-link
density (Table 8.2). Hence, phase separation obviously had the dominant
effect on the tensile and flexural properties of the four resins rather than
cross-link density.
The change in impact strength of the four resins is depicted in Figure 8.14.
The impact strength can reflect the toughness of a polymer matrix. The
TOPERMA70-ST30 and TOPERMA60-ST40 polymers had higher impact
strengths than the TOPERMA67-ST33 polymer, although they also had
higher cross-link densities. This is because the rubber TOPERMA-rich phase
absorbs the impact energy and improves the impact strength of the two
polymers.
10,23
The TOPERMA80-ST20 matrix had the lowest cross-link
density and the highest extent of phase separation, but showed the worst
toughness, which may be caused by having the lowest content of styrene and
the highest plasticizing effect of the pendant fatty acid chains.
8,24
Overall,
the effect of phase separation plays an important role in the mechanical
properties of TO-based thermosets.
8.3.3 Structure and Properties of the Cured DCPD-UPR-TO
Thermosets
8.3.3.1 SEM Analysis
The surface morphologies of the matrices obtained from DCPD-UPR-TO
polymers with different TO contents were investigated by SEM. Figure 8.15
shows the failure surface morphologies after the completion of impact tests.
In Figure 8.15(a), the surface of the DCPD-UPR matrix was generally flat and
