Ciencias Exactas y Ciencias de la Salud

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Mathematical modeling of ultrasonic micro injection molding using dimensional analysis for manufacturing polymeric parts
(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2020-11-23) Salazar Meza, Marco; Elías Zúñiga, Alex; hermlugo/tolmquevedo; Olvera Trejo, Daniel; Escuela de Ingeniería y Ciencias; Campus Monterrey; Martínez Romero, Oscar
Ultrasonic micro injection molding is a novel processing method to produce micro-scaled specimens at low production volumes that overcomes the material degradation originated by high residence times, and reduces material waste compared to conventional injection molding. Ultrasonic micro injection molding deals with ultrasonic energy and polymers under cyclic loads which experience a phase-change from solid to a non-Newtonian fluid flowing to fill a mold. Attempts have been made to study each of the steps of the process, all of them needing powerful FEM software and the establishment of several assumptions to simplify the calculus on the otherwise thermomechanical coupled problem with different time scales. This research work presents a methodology to reduce the mathematical complexity of the process while preserving the physics of the system through the usage of dimensional analysis. A correct relationship of processing parameters and energy consumption values was obtained using four different polypropylenes with distinct mechanical properties, all of them fitting adequately in the proposed formulation composed of dimensionless groups obtained through the Buckingham-Pi Theorem. A mathematical expression capable of quantitatively predict energy consumption from processing parameters was obtained. Additionally, a relationship between the processing parameters and the Young’s Modulus of the produced specimens was found, and a mathematical expression to calculate this property using processing parameters was stablished.
Mathematical modeling of the enzymatic saccharification process of lignocellulosic biowaste
(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2020-11) Fedeli, Vittorio; Mata Gómez, Marco Arnulfo; tolmquevedo; Calderón Oliver, Mariel; Aguilar Jiménez, Oscar Alejandro; School of Engineering and Science; Campus Monterrey; Gómez Sánchez, Carlos Eduardo
Lignocellulose is a biowaste produced in large quantities by industries; approximately 181.5 billion tons are produced annually in the world. This makes this type of residue a qualifiable candidate resource of energy, which nowadays, is underutilized. It is estimated that the food processing industry produces around 1.3 billion tons per year. In Mexico, the craft beer industry produces 3.8 thousand tons per year of brewers' spent grain. Being Mexico's fastest-growing industry, it can be considered a suitable source of biowaste. Brewers spent grain is considered a lignocellulosic material, which possesses a complicated structure containing lignin, hemicellulose, and cellulose. Due to its complexity, diversity, and recalcitrance to degradation, specific pretreatments to degrade it have been developed, such as biological, chemical, physical, and physicochemical. Notwithstanding, in nature, fungi are well-known microorganisms capable of degrading it through a tremendous battery of enzymes that are secreted in an ordered and systematic fashion. Nonetheless, the full understanding of this process, and the order in which each enzyme acts on lignocellulose, is far to be elucidated. Therefore, the present thesis aims to develop fungi bio-inspired mechanistic mathematical model capable of describing the enzymatic degradation process of lignocellulose biomass (brewers spent grain) and evaluate it through different experiments. Sequential addition of enzymes to biowaste, as well as experiments involving the addition of a pool without key enzymes that were further added at a specific time, were evaluated. Overall, results revealed that the lignin is not the most resilient and dense layer of lignocellulose as it has been believed. On the contrary, it seems lignin forms pore-like structures and diffuses through all different layers of this substrate. When hemicellulases (xylanases and pectinases) were not present in the enzyme pool, the reaction was not favored, indicating the importance of this polymer in lignin structure. These results gave an idea of how fungi work in nature and how the polymer layers are organized in lignin. However, to fully confirm these findings, more tests need to be performed to generate a robust and proven mechanistic mathematical model, enabling us to lay the foundations of a potential industrial-scale process.

Ciencias Exactas y Ciencias de la Salud

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