Jintao Wan

A novel biobased epoxy resin with high mechanical stiffness and low flammability: synthesis, characterization and properties

Exploring renewable biobased epoxy resins possessing intrinsic fire retardancy and high mechanical and thermal properties will greatly advance their potential to satisfy sustainability demands. Herein we develop a biobased route to synthesize a novel eugenol-based difunctional epoxy resin (TPEU-EP) with a full aromatic ester backbone. With 3,3′-diaminodiphenyl sulfone (33DDS) as the curing agent, TPEU-EP is compared with a standard bisphenol A epoxy resin (DGEBA) regarding their cure reactions and ultimate properties. The results show that TPEU-EP/33DDS expresses a higher reaction activation energy and a slower curing rate than DGEBA/33DDS. The isothermal cure reaction of TPEU-EP/33DDS is found to be autocatalytic. We accurately model the curing kinetics and elaborate on the related mechanisms based on the isoconversional analysis. The structure–property study reveals that TPEU-EP/33DDS manifests a 27%, 20% and 17% higher storage modulus (30 °C), Youngs modulus and hardness than DGEBA/33DDS, respectively. TPEU-EP/33DDS displays a high glass temperature (168.4 °C) and thermal stability (up to 300 °C), and shows a much higher damping than DGEBA/33DDS in the glassy state. Moreover, compared with DGEBA/33DDS, TPEU-EP/33DDS shows a 130% and 3.3 increase in char yield (in N2) and limiting oxygen index and a 68% and 40% decrease in the heat release rate and total heat release (microscale combustion test), respectively. Impressively, TPEU-EP/33DDS can self-extinguish in a vertical burning test, and the cone calorimeter test further confirms that TPEU-EP/33DDS has a much improved flame retardancy with a notably lowered smoke production. In brief, TPEU-EP possesses good intrinsic flame retardancy, low smoke production, and excellent mechanical properties, showing high promise for application. Our contribution will open a new avenue to develop sustainable high-performance flame-retardant epoxy resins.

Synthesis and characterization of functional eugenol derivative based layered double hydroxide and its use as a nanoflame-retardant in epoxy resin

Aiming to develop a multi-functional flame retardant for epoxy resins, a novel bio-based eugenol derivative containing silicon and phosphorus [((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(2-methoxy-4,1-phenylene)bis(phenylphosphonochloridate), SIEPDP] was synthesized, and was further used to modify Mg–Al layered double hydroxide (SIEPDP-LDH). This modified SIEPDP-LDH was used as a novel nanoflame-retardant for bisphenol epoxy resins and compared with unmodified pristine LDH. X-ray diffraction (XRD) analysis justified that intercalation of SIEPDP into LDH increased the interlayer distance to 2.95 nm. Morphological analysis (XRD and TEM) revealed that the SIEPDP-LDH was dispersed well in the epoxy matrix in a partially exfoliated manner. Results from the cone calorimeter tests showed that even a low loading of SIEPDP-LDH into epoxy resin led to a significant decrease in heat release rate and total heat release compared to unmodified LDH/epoxy composites. More interestingly, SIEPDP-LDH/epoxys UL-94 classification passed V-0 with only 8 wt% loading. Moreover, the addition of SIEPDP-LDH enabled the increase in the impact strength and modulus of the cured epoxy. These data indicated that SIEPDP-LDH could serve as not only a nanoflame retardant but a good reinforcing agent as well.

Synthesis and characterization of a Eu-containing polymer precursor featuring thenoyltrifluoroacetone and 5-acrylamido-1,10-phenanthroline

A polymerizable ligand, 5-acrylamido-1,10-phenanthroline (L), was synthesized. Its Eu(III) complex with 2-thenoyltrifluoroacetone (HTTA) was prepared and characterized by elemental analysis, IR, MS, and (1)H NMR spectra. The photophysical properties of the complex were studied in detail by using UV, luminescence spectra, luminescence lifetime and quantum yield. The complex shows a remarkable luminescence quantum yield at room temperature (40.1%) upon ligand excitation and a long (5)D(0) lifetime (590 μs), which makes it not only a promising light-conversion molecular device but also an excellent luminescent polymer precursor.