High Tg nematic thermosets Synthesis, characterization and thermo-mechanical properties

In this paper the synthesis and characterization of a new family reactive nematic oligomers based on 4-hydroxybenzoic acid (4-HBA) will be presented We modified the backbone using para- and meta-substituted aromatic monomers such as terephthalic acid (TA) isophthalic acid (IA) hydroquinone (HQ) resorcinol (RS) 4 4'-bisphenol (BP) and 3-hydroxybenzoic acid (3-HBA) All oligomers with a target M-n of 5000 and 9000 g mol(-1) were end-capped with reactive phenylethynyl functionalities and synthesized using standard melt condensation techniques Curing of the phenylethynyl reactive functionalities proceeds through chain extension and crosslinking depending upon the temperature and time and can be carried out between 310 and 400 degrees C Fully cured nematic thermosets could be obtained with glass-transition temperatures previously not accessible (T-g > 400 degrees C) The cured polymers exhibit excellent tensile properties i e tensile strength (83 MPa) and elongation at break (9%) This approach allows us to prepare all-aromatic polymers with a combination of useful properties such as ease of processing high T-g's and excellent mechanical properties (C) 2010 Elsevier Ltd All rights reserved