Reduction of cycle times in injection molding of PLA through bio-based nucleating agents

An approach to reduce cycle times in injection molding of poly (lactic acid) through the use of bio-based nucleating agents is presented. Talc is commonly used as nucleant and will be used as the reference in this study. The other investigated additives are kraft lignin, lignosulfonate, and carbon black. This is an in-depth study of certain bio-based nucleating agents for use with poly (lactic acid) under various processing conditions. Bio-based compounds of poly (lactic acid) and different nucleating agents were produced via twin-screw extrusion. Subsequent injection molding yielded standard samples for tensile testing; cycle times were recorded during injection molding. Thermal and mechanical testing showed direct dependence upon the degree of crystallinity in the matrix polymer. The ability of certain bio-based nucleating agents (e.g. kraft lignin) to reduce the cycle time in injection molding was proven.