DETERMINATION OF THE VISCOSITY TEMPERATURE COEFFICIENT (β) AND PSEUDOPLASTIC INDEX (n) OF POLY(LACTID ACID) (PLA)

Abstract

Poly(lactic acid) (PLA) is one of the most important ecological thermoplastics due to its good mechanical properties. In light of this, investigations related to the effects of PLA processing parameters are important as they affect the final product performance. This work aimed to determine the viscosity-temperature coefficient (β) and pseudoplastic index (n) of PLA and estimate its degradation rate during processing using an internal mixer. The viscosity coefficient was determined applying different processing temperatures at the same rotors rotation rate, which allowed estimating β = 0.048 ◦C−1. PLA’s pseudoplastic index (n) under the tested conditions suggested a value of approximately 0.71. PLA’s degradation rate was around 4% under rotor rate of 120 rpm and temperature of 190 ◦C.