Compound structure and mechanical properties of the natural polymeric cellular materials

The compressive yield stress and modulus of the two natural foam cores of kaoliang stem and corn stem were tested. Their structures and morphologies were determined by scanning electron microscope. The different compressive deformation mechanics of the foams were discussed. A compound structure model made up of hexangular prisms and tubular cells was established from the observation on scanning electron microscope photographs. The effects of the compound structure of the foams on their mechanical properties were studied on the basis of the model. The results show that the compressive yield stress and modulus of the two natural foam cores in the axial direction are more than 4 times of those in the radial direction. The compound structure of the foams reinforced by the tubular cells has more significant effects on the corresponding mechanical properties of the foams. The axial compressive modulus of a tubular cell is 105 times that of an abnormal hexangular prism cell.