Mathematical modeling of the magnetic-paper preparation process

The influence of six reaction variables on nine properties of magnetic paper was investigated. Magnetic properties were imported through in situ synthesis of cobalt ferrites and then charging these particles into the cellulose fibers during a lumen-loading step. As a first hypothesis, a multilinear model was selected in which the coefficients of the codified variables were calculated using linear regression by combining two-factorial partial experimental plans. Rather than predicting exact numerical values, the model gives the sign and relative magnitude of the variable coefficients, thus emphasizing the direction for improving magnetic and nonmagnetic properties. The results reveal some interesting trends. Above 40°C (the lower temperature limit for spinel formation via coprecipitation), the synthesis temperature does not play a significant role in any of the studied responses except crystallite size. However, higher pulp consistencies improve the ferrite properties. This indicates the importance of the nature of the particles formed in the presence of fibers during the in situ synthesis step. The validity of these and other observations was confirmed in subsequent experiments in which the reaction conditions were adjusted in the directions shown by the mathematical models. Application : preliminary studies to identify optimum reaction conditions for production of magnetic papers.