title: Multiple Cracks Propagate Simultaneously in Polymer Liquids in Tension.
abstract: Understanding the mechanism of fracture is essential for material and process design. While the initiation of fracture in brittle solids is generally associated with the preexistence of material imperfections, the mechanism for initiation of fracture in viscoelastic fluids, e.g., polymer melts and solutions, remains an open question. We use high speed imaging to visualize crack propagation in entangled polymer liquid filaments under tension. The images reveal the simultaneous propagation of multiple cracks. The critical stress and strain for the onset of crack propagation are found to be highly reproducible functions of the stretch rate, while the position of initiation is completely random. The reproducibility of conditions for fracture points to a mechanism for crack initiation that depends on the dynamic state of the material alone, while the crack profiles reveal the mechanism of energy dissipation during crack propagation.
authors: Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
authors: Qian
authors: Q
authors: Huang
authors: Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA.
authors: Nicolas J
authors: NJ
authors: Alvarez
authors: Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
authors: Aamir
authors: A
authors: Shabbir
authors: Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
authors: Ole
authors: O
authors: Hassager