Curing and Thermal Properties of PEPEB Liquid Crystalline Diepoxide/Aromatic Diamine

Abstract

The liquid crystalline epoxy resin p-phenylene di[4-2-(2,3-epoxypropyl)ethoxy] benzoate (PEPEB) was synthesized. The curing behavior of the liquid crystalline epoxy resin (LCER) with 4,4-diaminodiphenylmethane (DDM) was studied by fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and torsional braid analysis (TBA). Morphology of curing product was observed by polarized optical microscopy (POM) at different temperatures. Nonisothermal curing kinetics of this system were investigated by DSC. Results show that the PEPEB has a smectic liquid crystalline structure, and the melting point, T m , is 119 C, the clearing point is 184 C. The cured-system's gel point, T I , is 83.5 C; cure temperature, T P , is 111.6 C; and the disposal temperature, T f , is 145.8 C; activation energy of curing reaction is 4.84 KJ/ mol. Observation by POM shows that with the upgrade of initial curing temperature, the filament structure of this system transferred from anisotropy to isotropy.

Structural and electronic properties of carbon nanotube-reinforced epoxy resins

“…Epoxy resins serve as key elements in the field of high-performance materials, coatings, and composites. [1][2][3] The availability of a wide variety of epoxy systems, along with different physical performances associated with various cross-linking degrees, makes these thermosetting polymers extremely suitable for applications such as structural, medical, or aerospatial. Although epoxy resins are inherently brittle, curing processing in the manufacture of high-performance composites offers high modulus, stiffness and thermal stability.…”

“…Although epoxy resins are inherently brittle, curing processing in the manufacture of high-performance composites offers high modulus, stiffness and thermal stability. [1][2][3] In this regard, remarkable progress has been made in the curing of epoxy resins, and several studies have been performed to investigate the curing mechanism and the influence of various parameters on processing and material properties. 1,4 On the other hand, carbon nanotubes have been employed as reinforcers, which is connected to their unique properties and outstanding performance.…”

Curing and Morphology of BPA Epoxy Resin/LC Epoxy Resin PEPEB Composites

“…Liquid crystalline epoxy resin (BEPEB) was synthesized as known in literature [14,15] having melting point of 119 C and clearing point 184 C. The epoxy value of 0.385 mol=100 g was determined with Jay's method [16] . The molecular structure of BEPEB was characterized by 1 H NMR (Bruker 400 k, Switzerland) as follow: …”

Synthesis of multifunctional liquid crystalline epoxy resin embedded cyclic-siloxane chain with Tg-less behavior and enhanced toughness

“…Liquid crystalline (LC) epoxy resins are known to give both excellent mechanical and thermal properties due to the rigid mesogenic structure existing in the backbone moiety of networked polymer chains, such as biphenyl, 3 –7 stilbene, 8 –17 azomethine, 18 –27 ester, 28 –39 ketone, 40 and azo. 41,42 We have reported a remarkable improvement in fracture toughness and suggested the toughening mechanism of LC epoxy thermosets based on an analysis of the fracture process.…”