Polymer Engineering and Science, Vol.38, No.2, 311-321, 1998
Free radical branching of polylactide by reactive extrusion
The reactive extrusion of polylactide (PLA) with a free radical initiator resulting in a branched polymer was accomplished. Reaction conditions were in the range of 160 degrees C to 200 degrees C with an initiator concentration between 0.0 and 0.5%. Triple detector size exclusion chromatography, melt flow index, thermal gravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis were used to characterize the polylactide polymers. PLA without initiator showed extensive degradation as was evidenced by a decrease in both molecular weight and melt viscosity. The optimum range for branching resulting in a high molecular weight and low melt flow index polylactide was found to be around 170 degrees C to 180 degrees C and 0.1 to 0.25% initiator.