Akira Shinozaki

Simulation of Deformation Behavior of Polymeric Materials by Chain Network Model

The mechanical properties of polymers are strongly influenced by meso-scale (10-9~10-3 m) structure such as entanglement, molecular weight distribution, orientation, etc. It is important to understand the relationship between the mechanical properties of polymeric material and meso-scale structure. Some studies related to the relationship have been made. However detail of the relationship is still unclear. Especially, the studies emphasize on entanglement and branch are few. This study aims to clear the role of entanglement and branch for mechanical properties by simulating the meso-scale structure using 3D network models. In the models, there are two structures considered. One of them has no branch, and, others have branch. Large strain deformation of network models is evolved via improved molecular dynamics analysis.

Analysis of The Relationship Between Optical Property and Deformation Behavior of Polymeric Materials by Network Model

Polymeric materials are used in several parts because their flexibility, low cost and excellent in processing. It is important to understand the some properties of polymeric materials for optimized design. The properties of polymeric materials are strongly influenced by meso-scale (10-9-10-3 m) structure such as entanglement, molecular weight distribution, and orientation, etc. But it is difficult to investigate the relationship by experimental methods because the structures are micro scale. For this reason, the detail relationship between the properties and meso-scale structure is not clear. Computing power increases and increases, therefore it is possible to calculate behaviors of molecular chains. In this study, it is aimed to clear this relationship by the simulation. Mechanical properties are one of the important properties of polymeric materials. Therefore, the relationship between the mechanical properties and meso-scale properties has been investigated. But optical property is also important as well as mechanical property. In this study, we propose simulation method to investigate the relationship between the optical property and meso-scale structure. Polymeric materials are modeled by networks of molecular chain considered the meso-scale structure. In addition, polymeric materials are birefringence material. When the polymeric materials are elongated, refraction indexes of several directions become different values. A modeling of this change of refraction index is proposed. From these modeling, the light intensity distribution in a cross-section of square optical-waveguide is obtained. Then, the relationship between the change of structure of molecular chain scale and light intensity is investigated.

A Study of Deformation Behavior in Polymer

The mechanical properties of polymers are strongly influenced by meso-scale (10-9-10-3 m) structure such as entanglement, molecular weight distribution, orientation, etc. It is well known that sunlight induces the UV degradation of polymers. The mechanical properties of polymer are strongly influenced by UV irradiation because of chemical change of meso-scale structure. However the detail relationship between the mechanical properties and chemical change of meso-scale structure is not clear. In this study, it is aimed to clear this relationship by the simulation. Network models considered the meso-scale structure are constructed. Degradation is described to delete the chain elements in the network model. Large strain deformation of these network models is evolved via molecular dynamics analysis improved by us. It is possible to describe the degradation by this method.

Tensile Simulation of Polymeric Material Considering the Meso-Scale Structure

Several studies related to meso-scale structure and mechanical properties have been made. De Gennes[1] discussed the motions for one chain performing wormlike displacements inside a strongly corss-linked polymer gel. Theodorou and Suter[2] suggested the method for the detailed atomistic modeling of well-relaxed amorphous glassy polymers. Using molecular dynamics simulations, Stevens[3] studied the effect of interfacial bond density and network size on interfacial fracture. Hiroo[4] studied the coarse-graining is applied to flexible polymer chains. Yashiro[5] discussed the mechanical properties from atomistic scale. Marc [6] studied the orientation and crystallization of polyethylene during uniaxial extension. These works have been clarified some aspects of mechanical properties.

Analysis on Mechanical Behavior of Polymer by Molecular Chain Network Model : Effects of Molecular Weight Distribution and Ultra-Violet Degradation

A computational procedure for analyzing deformation and fracture behavior of solid polymers is developed based on a molecular chain model. In the model, the polymer solid is reprenented by a network of non-linear elastic chains. Van der Waals force and viscous force acting on the chains are taken into account and are approximated to act at the node points of the network. The stiffness equation is derived by employing the principle of virtual work, in which geometrical non-linearity due to large deformation are considered. The chain slippage and the chain session are also taken into consideration. A cellular automaton modeling is introduced to generate the network of polymer chains. The effects of molecularweght distribution and molecular chain session due to ultra-violet degradation are discussed through numerical analysis.

Effects of Meso-Scale Structure and Interactions on Macro-Scale Mechanical Properties in Polymeric Materials

The mechanical properties of polymers are strongly influenced by meso-scale structure such as entanglement, orientation, folded chain, etc. However, the relationship between the meso-scale structure and macro-scale mechanical properties of polymers has not been clarified. In this paper, network models of polymer chains are introduced to simulate the meso-scale interactions. From the FEM analysis of this model, the effects of interactions on macro-scale mechanical properties are investigated.