The effects of unidirectional drawing process on fracture behavior of poly(L-lactide) (PLLA), critical J-integral at crack initiation, Jin in the directions perpendicular and parallel to the drawing direction, fracture micromechanism, and surface roughness, R a were investigated. Unidirectional drawing machine was used with variation of draw-ratio from 1 to 2.5 and initial notches were introduced in the direction perpendicular or parallel to the drawing direction. Jin was found to be directly proportional to the draw ratio for the perpendicular direction and inversely proportional for the parallel direction, while similar was the case with R a, suggesting that rough surface formation resulted in high energy dissipation during crack initiation. The elongation and scission of the oriented molecules due to drawing creating rough surface are found to be the primary mechanisms of the toughness improvement due to drawing.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering