Chemistry Reference
In-Depth Information
1.3 Rosin-derived Rigid Curing Agents
Petroleum-based aromatic and cycloaliphatic anhydride compounds are often used as
curing agents for epoxies. Among those compounds BTCA, CHDA and their various
derivatives are two important types of curing agents widely used in industry. Through
relatively simple reactions, rosin acids can be converted to compounds of similar
functionality and structures [6].
Figure 1.6
shows two rosin derivatives, maleopimaric
acid (MPA) and MMP which respectively resemble BTCA and CHDA in structure
and functionality, but have bulkier molecular structures.
Figure 1.6
Rosin-derived anhydrides and their petrochemical analogues
Figure 1.7
compares the nonisothermal curing behaviours of these curing agents
with a liquid epoxy (DER332E, DuPont). The curing of DER332/CHDA, DER332/
BTCA or DER332/MMP each displayed a single exothermic peak in the DSC
thermograms, while the curing of DER332/MPA exhibited a double peak. The peak
at the lower temperature was associated with the cure reaction between carboxylic
acid and epoxide, whereas the peak at the higher temperature was attributed to the
cure reaction of anhydride and epoxide. Unlike MPA, the carboxyl and anhydride
