In the face of ever-growing concerns for environmental concerns, the need for eco-friendly materials is continually increasing. There is a call for polymers that are bio-resource based as opposed to the traditional petroleum-based plastics. However, performance issues of bio-based polymers indicate that blending with petroleum-based polymers would be beneficial. The outcome is a polymer with good performance, that also offsets petroleum incorporation in its derivatives. Two relevant candidates for blending are bio-based Poly(lactic acid) (PLA) and petroleum-based Acrylonitrile Butadiene Styrene (ABS). However, a major challenge in blending these two polymers is the choosing of optimal processing conditions. The gap between the melting temperatures of the constituent polymers creates a processing window in which there is a tradeoff between degree of mixing and the thermal degradation of the PLA. This thermal degradation of the PLA becomes prevalent especially at higher temperatures, causing a reduction in the molecular weight and the overall mechanical properties. This study aims to correlate to degree of degradation in parallel plate rheology to twin-screw extrusion at different temperatures in order to predict the effect of processing on the degradation of PLA. The rheological data has shown that the PLA shows a reduction in viscosity due to degradation of 87% at 220°C while only reducing by 37% at 180°C. The effect of blending with ABS on the degradation is studied, along with the subsequent effect of degradation on mechanical properties of the blends.