Synthesis and Properties of a Liquid Crystalline Thermoset Epoxy Resin Containing 1,3,4-Oxadiazole Groups

Abstract

A new liquid crystalline thermoset (LCT) based on 1,3,4-oxadiazole was prepared from liquid crystalline epoxy resin containing oxadiazole and diaminodiphenyl methane. The LCT was characterized and compared with the conventional thermoset. The Time—Temperature Transformation diagram was constructed to determine an appropriate set of cure cycles. The goal of this paper was centered on the evaluation of the mechanical performances of this new class of thermoset. In the case of LC thermoset, a higher Tg and good fracture resistance were noticed than that of the conventional thermoset. The LC thermoset exhibited higher thermal stability when compared with the conventional non-LC thermosets. The results tempted to consider the LCT materials as potential candidates for advanced composites.

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

“…In correspondence with the peaks in the tan δ curve, E was slightly reduced with increasing of temperatures and dropped further in Figure 1 when going through the glass transition. An analogous result was found by some authors for the epoxy system, for which two peaks in the dynamic mechanical spectrum were observed 8, 19, 27. Since thermoset networks are believed to arise from a competition among kinetic and thermodynamic factors,26, 28 their mobility has been discussed in the presence of hydrogen bonding, ion‐dipole forces and electron donor‐acceptor interactions among the components 29.…”

“…Liquid‐crystalline epoxy resins (LCERs) are composed of an aromatic mesogenic group and a reactive oxirane ring which takes part in the curing reaction with the curing agent. Many studies reveal that the liquid crystalline domain structure can increase impact resistance without sacrificing other properties 7, 17–20. The well‐balanced physical performance between the liquid crystalline polymer and epoxy resin provides a matrix resin for high‐performance polymer composites 21.…”

Tough epoxy/cyanate ester resins with improved thermal stability, lower dielectric constant and loss based on unique hyperbranched polysiloxane liquid crystalline

“…Generally, there are two toughening approaches, one is intrinsic toughening, which achieves toughening effect through changing the molecular structure of thermosetting resins or designing new molecules; the other is introducing various toughening agents. As the former is usually accompanied with complex synthetic routes, thus it is not easy to get industrialization, while the latter has advantages of wide selection and capability of easily adjusting the properties of resin, and thus has been the main toughening method …”

Synthesis and phase behavior of chiral liquid crystalline polymeric networks derived from menthol

“…Over the last decade, research on the LCNs has expanded rapidly. 1–12 According to the crosslink density, two classes of LCNs emerge: highly crosslinked liquid crystal thermosets and lightly crosslinked liquid crystal elastomers (LCEs). Recently LCEs have been paid increasing attention because they give rise to new macroscopic features by combining the mechanical properties of polymer networks with the anisotropic structure of the LC phase, which make them candidates for several applications, such as flexible displays, electromechanical actuators, and artificial muscles.…”