Crystallization of aromatic oligoester from bisphenol A and diphenyl terephthalate isophthalate mixtures

Wie succeeded in the crystallization of the title oligomeric ester, which w as denoted hereafter as polyarylate, and was sythesized by the melt condens ation polymerization of bisphenol A and diphenyl terephthalate/isophthalate (mole ratio 1/0.5/0.5) contacting with the proper solvent. Oligomeric poly arylate could be crystallized in a solvent whose solubility parameter was f rom 8 to 10. This oligomeric polyarylate had a heat of fusion from 2 to 20 J/g, and the melting temperature was changed from 140 to 220 degrees C depe nding upon the crystallizing solvent and the reduced viscosity of the oligo mer used. When the same oligomer was used for the crystallization, the melt ing point increased with the increase in the heat of fusion. However, with the increase in the reduced viscosity of the oligomer, the heat of fusion d ecreased, while the melting point and glass transition of the polymer incre ased with the increase in the reduced viscosity of the oligomer used, and f inally, both reached in the saturated points with the increase in the reduc ed viscosity of the oligomer used. The X-ray analysis for this solvent-indu ced crystalized oligomeric polymer showed partially crystalline nature. A s pherulite structure was observed using a photomicroscope, and a detailed st ructure of the crystallized structure was also discussed using a scanning e lectron microscope.