A non-cross-linked or partly cross-linked triaryl-s-triazine ring containing polymer or copolymer is prepared by cyclopolymerizing an aromatic nitrile-modified oligomer or precursor in the presence of excess molar amounts of aromatic nitrile at temperatures above 100.degree. C. to provide a non-cross-linked triaryl-s-triazine extended chain structure. The excess moles of aromatic nitriles above that required to endcap the oligomer results in an extended chain structure. The polymers are useful as a matrix laminating resin in composites containing carbon fibers and similar refractory filler materials to produce desirable refractory materials exhibiting thermal-oxidative stability at elevated temperatures.