Calorimetric investigations of hydrogen-bonded liquid crystal binary mixtures

Chandrasekar, G.; Prabu, N. Pongali Sathya; Mohan, M. L. N. Madhu

doi:10.1007/s10973-018-7688-7

Cited by 6 publications

(1 citation statement)

References 63 publications

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“…Liquid-crystalline (LC) compounds have been known for over 100 years, since they were discovered by Friedrich Reinitzer at the end of the 19th century [1]. Besides the low molecular mass liquid crystals, the solid polymeric liquidcrystalline materials are synthesized or analysed, including non-cross-linked and cross-linked ones with a variable density of cross-links [2][3][4][5][6]. Liquid-crystalline epoxy resins belong to a relatively new group of thermosetting materials, and their curing process is not yet completely understood.…”

Section: Introductionmentioning

confidence: 99%

Analysis of curing reaction of liquid-crystalline epoxy compositions by using temperature-modulated DSC TOPEM®

Mossety‐Leszczak

Kisiel

Lechowicz

et al. 2019

J Therm Anal Calorim

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The curing behaviour of the composition of a liquid-crystalline diepoxy monomer (LCEM) with the central triaromatic mesogenic group was studied using differential scanning calorimetry, conventional DSC and temperature-modulated TMDSC and nuclear magnetic resonance 1 H-NMR spectroscopy. The stoichiometric amount of primary aromatic diamine, 4,4 0-diaminodiphenylmethane (DDM), was used as a curing agent. TMDSC TOPEM Ò allowed the separation of the thermal effects related to reversible processes (e.g. phase transitions) from irreversible processes (cross-linking reaction) and determining that irreversible curing reaction occurs at the same time as reversible transition of the LCEM from crystal to the liquid-crystalline nematic phase. Additionally, 1 H-NMR analysis of the LCEM/DDM mixture preheated to a temperature from the temperature range of complex thermal changes was conducted. The obtained spectrum clearly showed the presence of partially cured products in the investigated samples and additionally proved that during the endothermic phase transition of the LCEM monomer an exothermic cross-linking reaction was occurring.

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