Predicting embrittlement of polymer glasses using a hydrostatic stress criterion

Abstract

In this study, the aging‐induced embrittlement of three polymer glasses is investigated using a previously developed hybrid experimental–numerical method. The evolution of yield stress of unnotched tensile bars upon aging is coupled to the evolution of embrittlement of notched tensile bars using a numerical model combined with a critical hydrostatic stress criterion that determines the onset of failure. The time‐to‐embrittlement of notched tensile bars with a different notch geometry is predicted and in good agreement with the experimentally determined value. Next to that, the approach is extended to three polysulfone polymers, and it is shown that the value of the critical hydrostatic stress correlates well with the polymers entanglement density: : polymers with a denser entangled network display higher values, that is, a higher resistance against incipient cavitation. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47373.

Predicting plasticity‐controlled failure of glassy polymers: Influence of stress‐accelerated progressive physical aging

“…The determination of the EGP model parameters for PPSU are described in two previous publications, but for completeness, they are listed in Tables and and in the Appendix. The first remaining parameter to be identified is the aging‐dependent part of the activation enthalpy.…”

“…The improvement in life time is principally caused by an increase in yield stress and, unfortunately, comes at a cost; upon physical aging strain softening increases as well, and a stronger tendency to strain localization results, ultimately leading to brittle failure under impact conditions . However, with proper methods, this change in failure mode under impact conditions can be predicted: the increase in yield stress leads to increases in local hydrostatic stress levels and brittle failure is triggered when the hydrostatic stress exceeds a critical value …”

Effective Industry–Academia Collaboration Driving Polymer Innovation

“…Successful innovation partnerships based on open sharing of knowledge accelerate co-development of innovation. , The problems addressed during the collaboration need to be both scientifically relevant for the academic partner and impactful in the industrial business. For example, the work performed by Leo (Solvay) and Govaert (Eindhoven University of Technology) on embrittlement of polymer glasses has been carried out over many years because of its complexity and scientific relevance. − Couty (Michelin) and Malfreyt (CNRS, Université Clermont Auvergne) have worked on polymer and polymer nanocomposites over the last 10 years because it still remains a very active field of research. − At the experimental and synthesis level, it would take years to list all of the fruitful collaboration between universities, national laboratories, and industrial companies. The work of Piunova at IBM (now at Loliware) on biofouling protection, for example, is remarkable, , and the long-lasting collaborative work between Bates at the University of Minnesota and Dow, Inc. have been recognized by the ACS through the 2008 ACS Cooperative Research Award and many publications showcase the quality of this work. − …”

“…For example, the work performed by Leo (Solvay) and Govaert (Eindhoven University of Technology) on embrittlement of polymer glasses has been carried out over many years because of its complexity and scientific relevance. 15 − 17 Couty (Michelin) and Malfreyt (CNRS, Université Clermont Auvergne) have worked on polymer and polymer nanocomposites over the last 10 years because it still remains a very active field of research. 18 − 21 At the experimental and synthesis level, it would take years to list all of the fruitful collaboration between universities, national laboratories, and industrial companies.…”

Micromechanical analysis of age‐induced strength reduction in a multiaxially loaded short‐fiber reinforced thermoplastic

“…[31][32][33][34][35][36][37][38] This sensitivity can be intensified by physical aging, as demonstrated for polycarbonate, [39][40][41] amorphous poly(aryl-ether-ether-ketone) 42 and polysulfones. 43 The influence of multiaxial stress states on the strength of SFRTs has, however, not been systematically studied. Most studies on failure of SFRTs employ (phenomenological) criteria based on a maximum stress or strain using for instance Tsai-Hill, 44 Tsai-Wu, 45 Hashin, 46 or Hoffman 47 based criteria.…”