Polymeric Composites with Cellulose Nanomaterials: Development of Synergistic Treatments and Stabilization Schema

by Blake Teipel

Institution: Texas A&M University
Year: 2016
Keywords: Cellulose; Nanomaterials
Posted: 02/05/2017
Record ID: 2093616
Full text PDF: http://hdl.handle.net/1969.1/158111


A combination of scientific and commercial research efforts are presented in this work. Exploits in both early- and late-stage research and subsequent scale-up opportunities are discussed, in particular, highlighting novel idea-to-market approaches suitable for composite materials with nanoscale fillers. Both polymeric and metallic nanocomposites are commercially explored, whereas answers to fundamental questions for polymeric composites filled with biologically derived nanomaterials are provided. In the first example, the role of a stabilizer in the stiffening and strengthening of cellulose nanocrystal (CNC) filled epoxy was studied. Cetyltrimethylammonium bromide (CTAB), a cationic surfactant, and Boehmite nanoclay (Boe) were mixed with CNCs in water during processing. Boe+CTAB synergistically stiffened the CNC-epoxy composites, increasing elastic modulus by 72% over neat epoxy and 49% over unstabilized CNC-epoxy composites. Boe-treated CNC-epoxy composites exhibited a 23% increase in tensile strength over unfilled epoxy and a 63% increase over an unstabilized CNC-epoxy composite. These nanocomposites also maintained the strain-at- failure of neat epoxy and increased the storage modulus above Tg by 96%. Then, in a second example, amine functionalization provided a functional layer between cellulose nanocrystals (CNCs) and polypropylene. Diethylenetriamine (DETA) was combined with polypropylene (PP) and then with CNCs in high-shear mixing. DETA-treatment stiffened the CNC-PP composites increasing elastic modulus by 75% over neat PP and untreated CNC-PP composites. DETA-treated CNC-PP composites also exhibited a 32% increase in tensile strength over unfilled PP and a 28% improvement for CNC-PP composites without DETA treatment. These nanocomposites were prepared without the use of organic solvents using a scalable, high-volume manufacturing approach. A commercial scale-up plan for this work is presented in detail. Thermal interface materials (TIMs) are required to enhance the contact between component surfaces, decrease thermal interfacial resistance, and increase heat conduction across the interface. A new TIM discussed herein is prepared using an already established technique of electrocodeposition, forming a flexible, nanocomposite film. The film is highly compliant, utilizing an ultra-high thermal conductivity greater than 250 W/m?K, as opposed to the best commercially available TIMs with conductivities ranging from 5?80 W/mK. This technology also achieves a total bulk thermal impedance of 1?4 ? 10-3 K?cm2/W, an order of magnitude lower than commercially available TIMs Advisors/Committee Members: Akbulut, Mustafa (advisor), Green, Micah (committee member), Creasy, Terry (committee member), Holtzapple, Mark (committee member).