Abstract: [Objective] The purpose of this paper was to explore the relationships between the bubble parameters(porosity, pore size and distribution) and mechanical properties of fiber porous cushioning packaging materials though appropriate characterizing methods of bubble parameters. This study provided theoretical basis for the preparation of fiber porous cushioning packaging materials with excellent performance, and a reference for further study on the foaming mechanism of the materials. Moreover,it would promote the development of green cushion packaging material.[Method]Wood powder and waste corrugated paper pulp were used as main materials, while adding auxiliary materials such as foaming agent. Foamed materials with different pore structures were prepared through hot press molding method. Then the micro image of materials was analyzed by the image processing software called Image Pro Plus 6.0, the bubble parameters of different materials such as porosity, pore size and distribution were obtained. Through the static compression test and the four compression rebound test, the stress-strain curves, the buffer coefficient stress curve, the average rebound rate curve of the 4 times and the deformation energy per unit volume were obtained. Then, the relationships between the structural parameters and mechanical properties of porous materials were discussed.[Result]Different parameters (porosity, pore size and distribution) showed different relationships with the mechanical properties of the material. The relationships between porosity and mechanical properties of materials were as follows: The higher the porosity, the gentler the stress-strain curve, the lower the minimum buffer coefficient and the less the deformation energy per unit volume were observed. With the increase of porosity, the average rebound rate of the material exhibited increased first and then decreased trend. The relationships between pore size and distribution and the mechanical properties of the material were as follows: The larger the percentage of big hole area, the smaller the stress value of the material under the same strain and the minimum buffer coefficient were obtained. The smaller the percentage of big hole area, that was, the more uniform the pore size distribution was more uniform, the higher the average rebound rate, the bigger the deformation energy per unit volume were achieved.[Conclusion] Through appropriate characterizing, experimental and statistical methods, different parameters (porosity, pore size and distribution) of fiber porous cushioning packaging material were characterized. The relationships between mechanical properties and pore parameters of different pore structure materials were obtained. These findings had important implications for the in-depth study on micro-structure of fiber porous cushioning packaging material, optimizing the pore morphology and uniformity, and even following production and preparation.

Key words: cushioning package, fiber, bubble parameters, mechanical property, computer image analysis