Publications Details

Crack propagation in highly cross-linked polymers under uniaxial deformation

Tsige, Mesfin; Stevens, Mark J.

Fracture of materials has a huge consequence in our daily life ranging from structural damage to loss of life. Understanding the mechanism of crack initiation and propagation in materials is very important. Great effort, both theoretically and experimentally, has been made to understand the nature of crack propagation in crystalline materials. However, crack propagation in disordered systems such as highly cross-linked polymers (e.g. epoxies) is less understood. Many composites such as carbon fibers have an epoxy matrix, and thus it is important to understand the epoxy properties by themselves. We study fracture in highly cross-linked polymer networks bonded to a solid surface using large-scale molecular dynamics simulations. An initial crack is created by forbidding bonds to occur on a fraction of the solid surface up to a crack tip. The time and length scales involved in this process dictate the use of coarse grained bead-spring model of the epoxy network. In order to avoid unwanted boundary effects, large systems of up to 300 000 particles are used. Stress-strain curves are determined for each system from tensile pull molecular dynamics simulations. We found that crack propagation and also formation of voids ahead of the crack are directly related to the network structure.