1] (OH) which did not appear in the FTIR spectra of DGEBF were observed.
Although the cured phosphorous-containing epoxy resin decomposed earlier than the control DGEBF at low temperature, significant improvement for thermal stability was detected at high temperature.
Furthermore, the char yield of the control DGEBF was only 0.
A phosphorus-containing epoxy resin was synthesized successfully by DOPO and DGEBF and its structure was confirmed by FTIR spectra.
Specimen Epoxy resin Curing agent S1 DGEBF DDS S2 P-DGEBF DDS TABLE 2.
Figure 2 also shows the glass transition temperature, which is assigned as the peak position of loss factor curve measured by DMA, of the DGEBF and the biobased neat epoxies cured with MTHPA.
Figure 4 shows the Izod impact strength of the anhydride-cured DGEBF and biobased neat epoxies.
Figure 5 shows SEM micrographs of the impact failure surfaces of the anhydride-cured DGEBF and biobased epoxy materials.
It is likely that the main epoxy matrix is more rigid than the separated ESO phase, since 100% ESO has much lower storage modulus at room temperature than DGEBF neat epoxy.
The DGEBF and ELO neat epoxies that did not have any phase separation exhibited a lower impact strength.
Figure 6 shows examples of load-crack opening displacement (COD) curves of the DGEBF and the biobased neat epoxies.
Figure 7 shows the fracture toughness of the anhydride-cured DGEBF and biobased neat epoxies.