Phosphorus-Free Ellagic Acid-Derived Epoxy Thermosets with Intrinsic Antiflammability and High Glass Transition Temperature

Abstract

Because fossil-based resources are constantly declining, it has become a crucial issue in both academic and industrial fields to develop biobased polymers from renewable resources. Despite excellent comprehensive properties, diglycidyl ether of bisphenol A (DGEBA)type epoxy resin suffers from nonrenewability and flammability. To overcome these shortcomings, a biobased epoxy monomer (DGEEA) derived from ellagic acid (EA) was successfully synthesized and well characterized in this study. The DGEEA monomer was cured by 4,4′diaminodiphenylmethane (DDM) to obtain a biobased epoxy thermoset, with DGEBA cured by DDM as a control sample. The cured DGEEA/DDM product showed a high glass transition temperature of 220 °C, a high tensile strength of 75.8 MPa, and a high Young's modulus of 2.7 GPa, which outperformed the conventional petroleumbased DGEBA/DDM system. Compared with the cured DGEBA/DDM system, the cured DGEEA/DDM product also exhibited an excellent intrinsic antiflammability in terms of the significantly decreased peak heat release rate (77.7 W/g versus 513.9 W/g) and the notably improved limiting oxygen index (40.0% versus 23.0%). Furthermore, the cured DGEEA/DDM product could self-extinct in the UL-94 vertical burning test (corresponding to the V-0 classification), while the cured DGEBA/DDM system burnt out eventually (no classification). The current study provides a prospective path for synthesizing biobased resin with abundant aromatic structures and makes a contribution to the generation of biobased fire-safe epoxy thermosets with exceptional comprehensive properties.

Synthesis of High-Tg, Flame-Retardant, and Low-Dissipation Telechelic Oligo(2,6-dimethylphenylene ether) Resins for High-Frequency Communications

“…Similarly, the total heat released for the DOPO-containing thermosets is lower than that of OPE-2St. The flame-retardant property of a polymer can be well-explained from their heat release capacity (HRC). , HRC values of DOPO-containing thermosets are lower than that of OPE-2St, and the trend is very similar to that of pHRR and THR data. All the MCC data are in agreement with the limiting oxygen index (LOI) results obtained from CYs of thermogravimetric analysis (TGA) experiments: LOI = 1.75 + (0.4 × CY), where DOPO-free OPE-2St produced a lower LOI value than DOPO-containing thermosets, and it is noted that a low LOI means high flammability.…”

Facile Synthesis of Eugenol-Based Phosphorus/Silicon-Containing Flame Retardant and Its Performance on Fire Retardancy of Epoxy Resin

“…The development of functional materials with desirable fire resistance has been a cynosure. , It is the most common method to enhance the flame retardancy through introducing flame retardants into polymers. , Epoxy resin is currently a typical polymer that occupies a dominant position due to its excellent mechanical properties, chemical stability, and bonding ability. − With the urgent demands for high-performance epoxy resin in the cutting edge areas such as electronic information, aerospace, and transportation, its flammability is of special importance. − Therefore, the development of a highly efficient flame retardant has become an essential prerequisite for high-performance epoxy resin. , …”

Intrinsic toughened conductive thermosetting epoxy resins: utilizing dynamic bond and electrical conductivity to access electric and thermal dual-driven shape memory

“…23 This stable crosslinked structure can furnish the cure epoxy resin with preeminent strength and a superhigh modulus. [24][25][26] However, the high crosslinking density of epoxy resin leads to its low fracture toughness, poor flexibility, and difficult recyclability. [27][28][29][30] These depressing drawbacks make the cured epoxy resin subject to the intrinsic problems of easily cracking and being hard to reshape once it is cured, which greatly limit the application scenarios and service life of epoxy resin floors, for instance.…”