Theory of Chain Pull-Out and Stability of Weak Polymer Interfaces. 1

Abstract

Polymer/polymer interfaces reinforced with block copolymers or grafted chains can fail by the pull-out of these chains. A number of constitutive models have been proposed in the literature to describe the pull-out of a single chain. In this paper, we use these models to construct a continuum theory of a weak interface, and we study the stability of such an interface subjected to a homogeneous deformation. We show tht if the perturbation contains a Fourier component with wavelength exceeding a critical value Λc, then the homogeneous deformation is unstable. The dependence of Λc on the geometry, the stiffness of the material outside the interface, and the pull-out models is derived. We also study the stress field near the tip of a preexisting interface crack using the different pull-out models.

Network Formation and Physical Properties of Epoxy Resins for Future Practical Applications

“…Since this feature is one of the greatest drawbacks for usage as a structural material and adhesive, it is desired to overcoming this problem. So far, many researchers have studied the fracture toughness for polymer glasses without any chemical cross-links. − Through a series of works, it is known that the toughness of polymer glasses depends on the molecular weight, or the apparent entanglement density, of chains. , This is explained in terms of the slippage of chains with others, induced by the deformation and/or craze formation. , Thus, once the chains are chemically cross-linked with one another, the chain slippage is expected to be suppressed, resulting in an improvement of fracture toughness. This strategy should work for epoxy resins but do not necessarily.…”

Adhesion and Debonding of Soft Elastic Films: Crack Patterns, Metastable Pathways, and Forces

“…9 The interfaces of weak polymers, however, behave differently. Debonding in weak polymer networks or in the peeling process of living cells under shear flow 10,11 leads to either complete pull out of polymer chains or cleavage of molecular bonds. Several models in the literature have been proposed regarding the rupture of such molecular bonds.…”

Coarse-Grained Molecular Dynamics Study of the Interface of Polymer Blends

“…For example, the effect of block copolymer reinforcement had been studied experimentally by Creton et al 1) and Washiyama et al, [2][3][4] who measured the fracture energy of the interface of polystyrene (PS) and poly(2-vinylpyridine) (PVP) reinforced by PS-PVP block copolymers with different molecular weight and interfacial densities. Theoretical studies of chain pull-out and crack growth along polymer interfaces have also been reported by Hui et al, [5][6][7] who found that the fracture toughness of the reinforced interface increased linearly with the areal density of block copolymer chains at the interface, and scaled with the square of the length of the shorter block of copolymers in the pull-out region, where the shorter block of copolymers was sufficiently short not to be entangled with other chains, and when no chemical bond scission occurred at the fracture.…”