Thermal and mechanical characteristics of polylactide filaments drawn at different temperatures

Polylactide (PLA) filaments produced by melt spin-drawing in different conditions (draw ratio, temperature of the draw roll) have been studied to demonstrate the influence of the process conditions on the tensile properties of the PLA filaments. Draw ratio varies from 2 to 3.5 and temperature of the draw roll from 80°C to 120°C. The thermal characteristics have been investigated using modulated differential scanning calorimetry (MDSC) and crystallinity using X-Ray Diffraction (XRD). Shrinkage of PLA multifilaments depending on the processing conditions is also investigated. It is demonstrated that the temperature of the draw roll is essential to obtain PLA filaments with optimum properties. At 80°C, the size of the lamellar crystals, measured using DRX, is not the highest. It is necessary to set the temperature of the draw roll at 110°C to obtain thick lamellar crystals. So, in those conditions, the PLA filaments have their optimum mechanical properties.