Degree Name

Master of Science (MS)

Semester of Degree Completion


Thesis Director

Ping Liu


The purpose of this research was to find a combination of poly (L-lactic acid), also known as poly-L-lactide or (PLLA) and antioxidants that would, together, produce a product whose degradation rate would be advantageous for use in biodegradable medical implants. Intrinsic viscosity tests were conducted on compression molded samples of PLLA that were molded at various processing parameters in order to find optimal parameters. The optimal processing parameters were found to be time 10 minutes, temperature 220°C, and pressure 1000 psi.

The molecular weight of PLLA sample was taken while pressure, time, and temperature were varied. As pressure increased, no significant change in molecular weight was noticed. When the time was increased, the molecular weight decreased. Then when temperature increased, the molecular weight of PLLA also decreased.

Compression molded samples were also made with a mixture of PLLA and antioxidants. At 0.6% of concentration, antioxidants in this study did not prove any benefits for PLLA to reduce the molecular degradation. All samples with 0.6% antioxidants showed lower molecular weight than pure PLLA.

Outcomes of this research provide a better understanding of biodegradable polymers and the factors that contribute to a successful mold. This research develops the best possible poly-L-lactic acid compression sample for further studies in the industry, including medical applications.