Introduction of phosphorus into the polyethyleneterephthalate molecule via disodium 1,2-dicarbomethoxyethylphosphonate—I. A study on the influence of the modifier-disodium 1,2-dicarbomethoxyethylphosphonate-on the properties of the pre-condensate

The effect of the concentration of disodium 1,2-dicarbomethoxyethylphosphonate as modifier in the trans-esterification stage of polyethyleneterephthalate preparation has been studied. It has been found that trans-esterification proceeds normally at modifier concentrations of up to 9% by weight, in respect of the combined weights of dimethylterephthalate and ethylene glycol, thus affording a precondensate with good characteristics.