Improved processing of thermotropic liquid crystalline polyesters

A series of thermotropic liquid crystalline polyesters based on p-hydroxybenzoic acid, terephthalic acid, 2,6-dihydroxynaphthalene and containing small amounts of either Bisphenol A, 2,7-dihydroxynaphthalene, or polyethylene terephthalate (PET) as comonomers were prepared. The latter three materials were investigated as a means of lowering the spinning temperature of the base polymer without sacrificing properties. Samples containing 1–2.5% Bisphenol A or 2.5–5% 2,7-dihydroxynaphthalene retained most of the properties (modulus fell slightly), but spinning temperature reduction was minimal. Polymers containing 2.5–5% PET retained full properties at spinning temperatures 60–80°C below the control.