The Influence of Different Concentrations of Orotic Acid on the Poly- Lactic Acid Crystallinity Development During Vibration Assisted Injection Molding

F.J. Alzahrani, P. Gao, A. Duhduh, J.P. Coulter
Lehigh University,
United States

Keywords: injection molding, orotic acid, poly-lactic acid


This research investigated the effect of the addition of different concentrations of Orotic Acid (OA) on the crystallization kinetics of Poly-lactic Acid (PLA) in non-quiescent conditions. DSC technique was utilized to capture the crystallinity, melting point, and other thermal parameters of PLA-OA blends. The influence of adding OA into PLA under non-quiescent conditions was investigated by using conventional injection molding (CIM) and vibration-assisted injection molding (VAIM). Two concentrations of orotic acid, 0.3 wt% and 0.7wt% were mixed with neat PLA and then molded at two different mold temperatures as following 80°C and 90°C. It was observed that the VIAM improved the overall cycle time by reducing the incubation time with maintaining the degree of crystallinity. At 90°C mold temperature, cooling time was reduced to 50% for both blends compared to samples molded at the 80°C mold temperature. For 2500HP PLA, Orotic acid (OA) showed to be an effective nucleating agent. A small amount (0.3 wt%) of Orotic acid was sufficient to achieve 61% of crystallinity in conventional injection molding at 80°C mold temperature for 100 seconds of cooling time. Also, the blend of PLA/0.3OA at 90°C mold temperature, able to achieve 50% of crystallinity during VAIM within only 45 seconds of cooling time.