Synthesis, phase behaviors, and mechanical properties of biphenyl‐type epoxy resins and composites

Abstract

Diglycidyl ether of 3,3 0 ,5,5 0 -tetramethyl-4,4 0 -biphenyl (TMBPDGE) which has been found great applications in semiconductor packaging was synthesized. The liquid crystalline phases of diglycidyl ether of 4,4 0 -dihydroxybiphenol (BPDGE) cured with phenol novolac (PN) were studied by wide angle X-ray diffraction (WAXD) and polarized optical microscopy (POM). BPDGE was in situ copolymerized with TMBPDGE to improve its thermal and mechanical properties by means of the LC domains retained in the crosslinked networks. The results indicated that a nematic phase was formed and fixed with proper curing schedule when BPDGE was cured with PN that had no neighboring active hydrogens and the LC domains could also be efficiently embedded into the composite systems. Dynamic mechanical properties showed that epoxy networks containing LC domains displayed higher a-relaxation temperature and linear elastic modulus traces. The impact toughness and T g were improved with the addition of BPDGE. Scanning electron microscope observation of the fracture surfaces showed that there was a change in failure mechanism in the composite systems.

Simultaneous reduction and surface functionalization of graphene oxide for enhancing flame retardancy and thermal conductivity of mesogenic epoxy composites

“…The epoxy monomer was 3,3',5,5'‐tetramethyl‐4,4'‐ biphenyl diglycidyl ether (TBDE), which was synthesized in our laboratory according to our earlier report . Scheme explains the chemical structure of the resultant synthesized epoxy.…”

Mechanical Properties and Morphology Studies of Thermosets from a Liquid‐Crystalline Epoxy Resin with Biphenol and Aromatic Ester Groups

“…In the nematic phase, as the 1/99 M1 /DGEBA in this study, however, the cross‐link motion was restricted in the direction perpendicular to the director and would result in a free energy penalty for disruption of the liquid crystalline phase. Nematic phase owned higher storage modulus than isotropic network 7, 31. Therefore, the rubbery plateau modulus of 1/99 M1 /DGEBA was higher than that of 10/99 M2 /DGEBA.…”

“…The formation of the cross‐linked network also enhanced steric shielding (the “screening effect”) and decreased the accessibility of hydrogen bonding between group pairs, resulting in a reduction of the specific interactions between M1 and epoxy resin chains and may resulting in higher T g in M1 /DGEBA blends 33, 34. However, it was hard to interpret these data conclusively since glassy deformations were primarily governed by intermolecular van der Waals forces and short‐range enthalpic deformations of the individual molecules including bending, rotating, and stretching of network strands 31. Specific intermolecular interactions in such systems were much more complicated than in linear polymer blends.…”

Anisotropic thermal conductivity and flame retardancy of nanocomposite based on mesogenic epoxy and reduced graphene oxide bulk

“…This monomer contains biphenyl mesogen. Its chemical structure was confirmed and liquid crystallinity was studied in our previous work [18,19].…”

“…Biphenyls mesogenic epoxy named 3, 3 0 , 5, 5' -tetramethyl-4, 4 0 biphenyl diglycidyl ether (TBDE) was synthesized in our laboratory according to our early reports [18]. Chemical structure of the resultant synthesized epoxy and harder used in this study were depicted in Scheme 1.…”