Effect of Cyclotrimerization of Bisphenol-A Dicyanate Monomer on Poly(ethylene terephthalate) Chain Extension

The engineering application of poly(ethylene terephthalate) (PET) was limited by its low melt viscosity and strength. Numerous chain extenders were used to enlarge the molecular weight so as to overcome these shortcomings including bisphenol-A dicyanate (BADCy), which was proven effective in one of our previous work. It was considered that tri-mer of BADCy through cyclotrimerization might strengthen the effectiveness in chain extender for PET, and the effect of BADCy tri-mer was studied in this work. With increasing the cyclotrimerization reaction temperature of BADCy monomer, the conversion to tri-mers was increased. With a fraction of BADCy tri-mer in the chain extender, the modified PET exhibited higher melt torque, intrinsic viscosity, melt modulus, and melt viscosity than those modified by BADCy monomer alone. BADCy tri-mer had a positive effect on the chain extension of PET. However, the fraction of tri-mers in the monomer/tri-mer mixture should be limited to a certain value; otherwise, the chain extension would be weakened. POLYM. ENG. SCI., 51:1791-1796, 2011. (C) 2011 Society of Plastics Engineers