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Title: Tensile Fracture of Welded Polymer Interfaces: Miscibility, Entanglements, and Crazing

Large-scale molecular simulations are performed to investigate tensile failure of polymer interfaces as a function of welding time t. Changes in the tensile stress, mode of failure and interfacial fracture energy G I are correlated to changes in the interfacial entanglements as determined from Primitive Path Analysis. Bulk polymers fail through craze formation, followed by craze breakdown through chain scission. At small t welded interfaces are not strong enough to support craze formation and fail at small strains through chain pullout at the interface. Once chains have formed an average of about one entanglement across the interface, a stable craze is formed throughout the sample. The failure stress of the craze rises with welding time and the mode of craze breakdown changes from chain pullout to chain scission as the interface approaches bulk strength. The interfacial fracture energy G I is calculated by coupling the simulation results to a continuum fracture mechanics model. As in experiment, G I increases as t 1/2 before saturating at the average bulk fracture energy G b. As in previous studies of shear strength, saturation coincides with the recovery of the bulk entanglement density. Before saturation, G I is proportional to the areal density ofmore » interfacial entanglements. Immiscibiltiy limits interdiffusion and thus suppresses entanglements at the interface. Even small degrees of immisciblity reduce interfacial entanglements enough that failure occurs by chain pullout and G I << G b.« less
 [1] ;  [2] ;  [3]
  1. Johns Hopkins Univ., Baltimore, MD (United States). Department of Physics and Astronomy; Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Chemistry
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  3. Johns Hopkins Univ., Baltimore, MD (United States). Department of Physics and Astronomy
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0024-9297; 537227
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 47; Journal Issue: 19; Journal ID: ISSN 0024-9297
American Chemical Society
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States