Anomalous ductility in thermoset/thermoplastic polymer alloys: An explanation based on overlap concentration and cavity growth

Debashish Mukherji; Cameron F. Abrams

doi:10.1209/0295-5075/88/56001

All issues

Volume 88 / No 5 (December 2009)

EPL, 88 5 (2009) 56001

Abstract

Issue		EPL Volume 88, Number 5, December 2009


Article Number		56001
Number of page(s)		5
Section		Condensed Matter: Structural, Mechanical and Thermal Properties
DOI		https://doi.org/10.1209/0295-5075/88/56001
Published online		07 December 2009

EPL, 88 (2009) 56001

Anomalous ductility in thermoset/thermoplastic polymer alloys: An explanation based on overlap concentration and cavity growth

Debashish Mukherji and Cameron F. Abrams

Department of Chemical & Biological Engineering, Drexel University - Philadelphia, PA 19104, USA

Corresponding author: debashish.mukherji@drexel.edu

Received: 4 September 2009
Accepted: 9 November 2009

Abstract

Using large-scale molecular-dynamics simulations, we investigate the mechanical behavior of thermoset/thermoplastic polymer alloys. We focus here on the effect of linear-chain mass fraction $\Gamma _{l}$ , for different chain lengths N_l, and strain rates $\dot{\varepsilon}$ . Our results show that tensile strain (i.e., strain to break) decreases with increasing $\Gamma _{l}$ up to a threshold value $\Gamma ^{*}_{l}$ , beyond which it increases with $\Gamma _{l}$ . This non-monotonic behavior, which we call “anomalous ductility", is qualitatively independent of $\dot{\varepsilon}$ and N_l, so long as fracture occurs in bulk. However, for larger strain rates (i.e., $\dot{\varepsilon} \geqslant 5 \times 10^{-4} \tau^{-1}$ ) adhesive fracture occurs and no anomalous ductility is observed. $\Gamma ^{*}_{l}$ decreases with increasing N_l and we observe microscopic evidence that $\Gamma ^{*}_{l}$ signifies the onset of interchain interactions. A simple scaling argument suggests that $\Gamma ^{*}_{l}$ is related to the overlap concentration c^* of the thermoplastic homopolymer in the cured thermoset matrix.

PACS: 61.41.+e – Polymers, elastomers, and plastics / 87.15.La – Mechanical properties / 87.10.Tf – Molecular dynamics simulation

© EPLA, 2009

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