2.2.3. Orthogonal experimental design
Different reaction conditions had a great influence on the performance of the material. To determine the optimum reaction conditions for the preparation of AP and SP, the orthogonal experimental design was introduced by Statistica 8.0. A total of 16 experiments were carried out to investigate the effect of three variables (reaction temperature, reaction time and catalyst dosage) and five variables (reaction temperature, reaction time, the amount of monomer, the amount of cross-linking agent and initiator dosage) on the oil absorbency of AP and SP, respectively. The amount of oil absorbency for diesel was chosen as indicator to investigate the optimal reaction conditions. The preparations for AP and SP in the experiments were repeated two times to reduce errors.