GOALI: Determination of the Structure and Properties of Microfibrillated Cellulose during Dynamic Phase Transitions

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Microfibrillated cellulose (MFC) is a waste product generated during paper manufacturing. It is processed commercially for some industrial uses, but it also has a potential application as a rheological modifier in consumer, fabric and home care products. Rheological modifiers are materials added to certain products to customize their flow behavior. MFC is non-ionic, which makes it compatible with a wide range of product recipes, but it must be dispersed throughout a product to modify the product's properties. The challenge is that MFC is supplied as a concentrated slurry of highly entangled fibers in water that are difficult to disperse in most products. This GOALI project, which is a collaboration between Lehigh University and Procter and Gamble, will investigate how the structure of MFC depends on parameters such as the temperature, composition of the host solution and forces exerted on MFC due to flow. Using several techniques that probe the microstructural arrangements of the MFC fibers, the researchers explore transitions in the microstructure that can enhance dispersal of MFC in useful products. Repurposing MFC waste from the paper industry as additives for consumer products will reduce the need for MFC disposal and reduce manufacturing costs of valuable consumer products. The research team will engage in a variety of outreach activities, including programs at the Da Vinci Science Center to educate the public in colloids and rheology, mentoring middle school and high school students interested in STEM fields, and training undergraduate and graduate students in research.The overall goal of this GOALI project is to characterize the spatial and temporal rheological evolution of an MFC scaffold to enable its use as a rheological modifier for consumer, fabric and home care products. MFC has a fiber size that is comparable to the fiber size of rheological modifiers in current use, but unlike other modifiers, MFC has negligible charge on the colloid. The potential advantages of MFC will be explored by characterizing the microstructural evolution of MFC using microrheology and microscopy, by characterizing the evolution of bulk rheology of MFC systems, and by determining equilibrium properties and scaffold structure after phase transitions using a unique microfluidic platform and multiple particle tracking microrheology. MFC solutions will be characterized during phase transitions due to three driving forces: temperature, changes in the surrounding solution and flow-induced mechanical forces. This knowledge will enable the use of these materials as rheological modifiers for the formulated product industry. The results of the research will identify materials that lead to homogeneous MFC suspensions and determine the microstructure and macroscopic structure and properties that lead to stable suspensions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.