Pyrolysis – capillary gas chromatography combined with on‐line alkylation for the compositional analysis of liquid crystalline aromatic polyesters

Pyrolysis–capillary gas chromatography combined with on‐line alkylation has been employed for compositional analysis of liquid crystalline aromatic polyesters (LCPs) based on p ‐ hydroxybenzoic acid. The fundamental conditions were examined using an LCP prepared from p ‐hydroxybenzoic acid, terephthalic acid, and 4,4′‐biphenol and every constituent of a sample weighing ca. 50 μg was almost quantitatively recovered as its dimethyl derivative in the pyrogram obtained following pyrolysis at 400°C in the presence of 1 μl of 25% tetramethyl‐ammonium hydroxide in methanol. The compositions of a variety of terpolyesters and LCPs containing isophthalic acid or 2‐hydroxy‐6‐naphthoic acid units have been precisely deter‐mined by pyrolysis‐methylation GC.