Molar mass determination of polylactic acid alternatives by capillary viscometry method

Abstract

The molar mass of polymers is a basic property that defines the appropriate processing method and the field of application of polymers. Therefore, the measurement of molar weights is a crucial point of polymer synthesis. In absence of modern but expensive equipment a rheology-based method can be used to define the molar mass with reliable result. By evaluation of molar mass, the entire polymerization can be monitored and controlled. During my experiments polylactic acid alternatives (PLLA, PDLA, PDLLA) have been synthesized by direct polycondensation methods. According to the relevant literature, by this method and with the adequate setup of its parameters 104-105 g•mol-1 molar mass can be reached. The two most important parameters are the process time and temperature that strongly effects on the value of molar mass of polymer. In this work standard polycondensation method has been used to produce the mentioned polylactic acid alternatives then the molar masses of polylactic acid polymers were calculated by followed the correlation of Mark - Houwink relation.