Influência da concentração de fosfito de trifenila e das condições de processamento na extensão de cadeia do poli (tereftalato de etileno).

Abstract

This work deals with reactive processing of virgin PET with triphenyl phosphite (TPP). Processing was performed without inert atmosphere injection in the mixing chamber of a Haake Torque Rheometer. PET chain extension was investigate as a function of TPP concentration, processing time and temperature, rotor speed, identity and content of stabilizers. Our results confirm that processing of PET in the presence of TPP results in chain extension, as confírmed by carboxyl end-group analysis. It was shown that chain extension takes place a few minutes after TPP addition and the amount of extension is highly dependent on TPP content, processing time and temperature and rotor speed. Maximum chain extension was obtained for PET processed with 1% TPP for 11 minutes at 260°C and 60rpm. The stabilizers employed, Irganox 11425 e Irgafos 168, did not effectively stabilize PET processed with TPP. According to the data obtained for carboxyl end-group concentration, PET processed with TPP, considerably degrades during 32 weeks storage under local conditions of humidity and temperature.