Improvement in Properties of Semi-Aromatic Liquid Crystal Polyesters

A new semi-aromatic LCP (new LCP) was synthesized by an improved reaction process consisting of divided additions of p-acetoxybenzoic acid to poly (ethylene terephthalate) (PET) in order to improve properties of the well-known p-hydroxybenzoic acid (PHB) / PET copolyester (old LCP). This new LCP which has a less blocky monomer alignment, exhibits greatly improved mechanical and thermal properties. The small particles comprising homopolymerized PHB blocks which do not melt at an injection molding temperature were considered to disturb the molecular orientation of the old LCP. Poor heat deflection temperature of old LCP may have been affected by a fraction of old LCP which doesn't have crystallinity.