Coarse-Grained Simulation Model for Crystalline Polymer\nSolids by Using Breakable Bonds

We propose a highly coarse-grained\nsimulation model for crystalline\npolymer solids with lamellar structures. The mechanical properties\nof a crystalline polymer solid are mainly determined by the crystalline\nlamellar structures. This means that coarse-grained models rather\nthan fine-scale molecular models are suitable to study the mechanical\nproperties. We model a crystalline polymer solid by using highly coarse-grained\nparticles, of which the size is comparable to the crystalline layer\nthickness. One coarse-grained particle consists of multiple subchains\nand is much larger than monomers. Coarse-grained particles are connected\nby bonds to form a network structure. Particles are connected by soft\nbut ductile bonds to form a rubber-like network. Particles in the\ncrystalline region are connected by hard but brittle bonds. Brittle\nbonds are broken when large deformations are applied. We perform uniaxial\nelongation simulations based on our coarse-grained model. As the applied\nstrain increases, crystalline layers are broken into pieces and nonaffine\nand collective motions of broken pieces are observed. Our model can\nsuccessfully reproduce yield behaviors that are similar to typical\ncrystalline polymer solids.