Synthesis Of Rosin-based Curing Agents And The Curing Behavior With Epoxy Resin

In the current situation, as non-renewable resources such as petroleum dried up gradually, as well as the growing awareness of the growing importance of environmental protection, bio-based synthetic material polymer has become a hot research field. As we know, rosin is an important natural product, also a renewable resource. Due to their large hydrogenated phenanthrene ring structure, rosin acids are similar in rigidity to petroleum-based cycloaliphatic or aromatic compounds. As a result, rosin for the synthetic polymer research is causing great attention. In this paper, rosin acid as alternatives to petrochemical to modify epoxy curing agents, and rosin-based ester anhydride curing agent, rosin-based imide amine-type curing agent, rosin-based imido amine-type curing agents were synthesized, and study the curing behavior with epoxy resin.The main research results were described as the below:1. Synthesis of rosin-based ester anhydrides Rosin ester anhydrides were started from the esterification of abietic acid with polyol followed by the Diels-Alder reaction with maleic anhydride. The product was used to cure bisphenol A epoxy resin. Their chemical structures were confirmed by FTIR and XPS. TGA plot of the curing product showed that the thermal degradation temperature, T5% is beyond 300℃which proved that the epoxy resin cured with rosin-based ester anhydrides have excellent thermal stability.2. Synthesis of rosin-based imide amine-type curing agent Rosin-based amido were synthesized by Diels-Alder reaction between rosin and fumaric acid or acrylic acid, and then the product was reacted with diamine. Their chemical structures were confirmed by FTIR and XPS. The product was used to cure bisphenol A epoxy resin. TGA plot of the curing product showed that the thermal degradation temperature, T5% is beyond 300℃which proved that the epoxy resin cured with rosin-based ester anhydrides have excellent thermal stability.3. Synthesis of rosin-based imido amine-type curing agents and the curing behavior with epoxy resin Rosin-based imido amine-type was synthesized by Diels-Alder reaction between rosin and maleic anhydride and then product was reacted with diamine. The chemical structure was confirmed by 1 H NMR, FT-IR and ESI-MS. The curing behavior with diglycidyl ether of bisphenol-A epoxy was studied, as comparison, the curing behavior of another kind of rosin-based anhydride curing agent, MPA and a kind of commercial aromatic curing agent, diaminodiphenyl methane (DDM) were also studied using differential scanning calorimetry. The activation energy and the pre-exponential factor (A) of the DGEBA1075/MPA-ED, DGEBA1075/DDM, DGEBA4000/MPAIA, DGEBA1075/MPA systems were determined by both Kissinger's and Ozawa's methods for accuracy of results, equation of DGEBA1075/MPA-ED was also obtained. The thermal mechanical properties and thermal stability of the cured epoxy resins were evaluated using dynamic mechanical analysis and thermogravimetric analysis, respectively. Cured products have good thermal stability due to the presence of imide group and the bulky hydrogenated phenanthrene ring structure. Rosin acids have a great potential in the synthesis of epoxy curing agents to take place some of current commercial aromatic or cycloaliphatic analogs.