Effective Factors on Molecular Packing and Its Effect on Mechanical Properties of Epoxy

Cured epoxy is a thermosetting polymer with amorphous structure. The amorphousphase structure reflects the mechanical thermal history of a polymer. Many parametersin the structure of the amorphous phase affect physical and mechanical properties. One ofthe rarely considered parameters is molecular packing. The purpose of this study is toinvestigate the factors affecting molecular packing, which leads to changes in mechanicalproperties. The measurement of molecular packing by x-ray diffraction is carried outusing the Bragg equation and its approximate estimation is acquired using macroscopicdensity. Other equations for calculating chain diffraction and crystal size are introducedin semi-crystalline systems. Studies have shown that the presence of rigid structures inthe backbone increases the tendency for arrangement. In addition, the branch tends toincreased packing and mechanical properties when it is smaller than the free space betweenthe chains. Generally in adding additive, the effect increases on molecular packing byreducing the particle scale. Also, the presence of surface modifiers on particles, especiallyin nanoscale particles, results in a matrix arrangement around the particle, an increase inmolecular packing and mechanical properties. The addition of a plasticizer in the system inthe case of fuzzy separation, as the bubble phase becomes larger, there is a reduction in the amount of packing in the chain and displaces the amorphous halo towards smaller angles.