There are many types of foam molding methods. The most commonly used methods are the pressure foaming method, in which foam resin is mixed with a foaming agent at high temperature and high pressure, and the normal pressure foaming method, which foams at high temperature without pressure. The polymer resins used for foaming have different viscosities. For foaming under normal pressure, they need to be designed and analyzed for optimal foaming conditions, to obtain resins with low melt-viscosity or a narrow optimal viscosity range. This study investigated how changes in viscosity, molding temperature, and cross-link foaming conditions affected the characteristics of the molded foam, prepared by blending rubber polymer with biodegradable resin. The morphologies of cross sections and the cell structures of the normal pressure foam were investigated by SEM analysis. Properties were also studied according to cross-link/foaming conditions and torque. Also, the correlation between foaming characteristics was studied by analyzing tensile strength and elongation, which are mechanical properties of foaming composites.

1. Introduction
2. Experimental Procedure
    2.1. Materials and formulation
3. Results and Discussion
4. Conclusion

• Dong Hun Han(Department of Organic Material Science and Engineering, Pusan National University, Busan 46241, Republic of Korea, Korea Institute of Footwear & Leather Technology, Busan 47154, Republic of Korea)
• Young Min Kim(Korea Institute of Footwear & Leather Technology, Busan 47154, Republic of Korea)
• Dan Bi Lee(Korea Institute of Footwear & Leather Technology, Busan 47154, Republic of Korea)
• Kyu Hwan Lee(Korea Institute of Footwear & Leather Technology, Busan 47154, Republic of Korea)
• Han-Seong Kim(Department of Organic Material Science and Engineering, Pusan National University, Busan 46241, Republic of Korea) Corresponding author