*3.3. Computational Prediction of the CBA and CMF Performance in Formulations with 100% Eucalyptus Fibers*

The high manufacturing costs associated with tissue paper materials are due to the market softwood pulp prices and the energy consumption associated with the fiber modification processes such as refining or beating. Finding strategies to reduce these processes is one of the focuses of the research on the management and optimization of the furnish and each type of tissue product. For this reason, we developed a tissue simulator, SimTissue, with the ability to predict the final end-use properties of different hypothetical scenarios of industrial interest. Our approach in this study was to estimate improvements in tissue properties with the incorporation of CBA and CMF, separately, in formulations with 100% eucalyptus fibers compared with formulations containing eucalyptus fibers and softwood fibers (Figure 12). Note that these simulations were carried out with a reinforcing fiber with high strength properties, according to a set of pulps studied previously [6,7]. It is important to present the simulations of these fiber mixtures as they represent the limits achievable in the tissue properties.

**Figure 12.** Evolution of the end-use tissue properties of softness HF, tensile index and water absorption capacity with the incorporation of CBA (**a**), CMF (**b**) and softwood fibers (**c**) in formulations with 100% eucalyptus fibers. All variables were normalized to present the same scale range.

As expected, the incorporation of CBA, CMF and softwood fibers promoted an improvement in strength properties with adverse effects on softness and absorbency. According to the tissue simulator, a formulation with 90% eucalyptus fibers and 10% softwood fibers promoted the production of a tissue product with a 68 softness HF, 15 Nm/g tensile index and 8 g/g water absorption capacity [24]. In order to replace this softwood fiber, the incorporation of 3% CBA allowed us to obtain improved tissue properties in the same range (72 softness HF, 15 Nm/g tensile index and 8 g/g water absorption capacity). The

same trend was also verified for the incorporation of 14% CMF, presenting 70 softness HF, 15 Nm/g tensile index and 7 g/g water absorption capacity. However, in a previous work, we found that formulations with more than 10% CMF incorporation are not economically viable. The trade-off between the cost and the effectiveness of the formulations was achieved with the incorporation of CMF between 1 to 8%, presenting optimized properties at an industrial range [24].

This approach saves the consumption of softwood fibers in tissue production and is aimed at the use of biocompatible and biodegradable additives in the industrial production process. The simulator's predictive capacity allowed the optimization and development of innovative formulations, saving laboratory and industrial resources.
