Fig. 9 illustrated the notched Izod impact strength of the foamed PVC/rice hull composites. The impact strength decreased as the level of the mAC was increased from 0–2.0 wt.%, but there was an upturn when the mAC reached 3.0 wt.%. A similar reduction was also found in the literature reported by Mengelu and Matuana. This was believed to have resulted from the thicker cell wall, created when mAC 5 lm was applied, which functioned as a continuous phase absorbing the energy upon impact. Greater impact strength was achieved when mAC 5 lm was applied. Fig. 10 shows the foam structure when different particle sizes of mAC were applied at 1.0 wt.%. Also illustrated in Fig. 10a–d were the changes in the cell size created by each particle size of mAC