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Item Comparing the mechanical properties of shale cores: intact vs. fractured and sealed with UICP(Montana State University - Bozeman, College of Engineering, 2023) Bedey, Kayla Marjorie; Chairperson, Graduate Committee: Catherine Kirkland; This is a manuscript style paper that includes co-authored chapters.Fractures in subsurface shale formations are instrumental in the recovery of hydrocarbon resources. A result of hydraulic fracturing, these fractures have the potential to become harmful leakage pathways that may contribute undesired fluids to the atmosphere and functional groundwater aquifers. Ureolysis-induced calcium carbonate precipitation (UICP) is a biomineral solution where the urease enzyme converts urea and calcium into calcium carbonate mineral. The resulting biomineral can bridge gaps in fractured shale, reduce undesired fluid flow through leakage pathways, limit fracture propagation, better store carbon dioxide, and potentially extend the efficiency of future and existing wells. The mechanical properties of fractured shale sealed with UICP was investigated using a modified Brazilian indirect tensile strength test. Part one of this study investigated the tensile strength of shale rock using intact Eagle Ford (EF) and Wolfcamp (WC) shale cores (5.08 cm long by 2.54 cm diameter) tested at room temperature (RT) and 60°C. Results show no significant difference between shale types (average tensile strength = 6.19 MPa). EF cores displayed a higher strength at RT versus 60°C, but no difference was seen between temperatures for WC cores. Part two used UICP to seal shale cores (5.08 cm long by 2.54 cm diameter) with a single, heterogeneous fracture spanning the core length. UICP was delivered two ways: 1) the flow-through method injected 20-30 sequential patterns of microbes and UICP-promoting fluids into the fracture until fracture permeability reduced by three orders of magnitude and 2) the immersion method placed cores treated with guar gum and UICP-promoting solutions into a batch reactor, demonstrating that guar gum is a suitable inclusion to UICP-technology and may be capable of reducing the number of injections required in flow-through methodology. Tensile results for both flow-through and immersion methods were widely variable (0.15 - 8 MPa), and in some cores the biomineralized fracture split apart. Notably in other cores the biomineralized fracture remained intact, demonstrating more cohesion than the surrounding shale, indicating that UICP may produce a strong seal for subsurface application.Item Transforming wood into a high-performance engineering material via cellulose nanocrystal impregnation(Montana State University - Bozeman, College of Engineering, 2023) Chan, Ashton Oriel; Chairperson, Graduate Committee: Dilpreet S. BajwaA significant challenge in this world today is innovating sustainably sourced materials for advanced engineering applications. Cellulose nanocrystals (CNCs) have excellent potential in these advanced applications as reinforcement in softwood because of their inherent biodegradability, universal accessibility, and exceptional mechanical properties. This research aimed to design a novel method to impregnate cellulose nanocrystals into marginal-quality softwood to enhance its mechanical properties for advanced engineering and architectural applications. In this research, southern yellow pine (SYP) wood underwent sodium hydroxide treatment to remove lignin from the wood cells. Then, SYP samples were submerged into a surface-functionalized (by either acetic acid or benzoic acid) CNC solution and subjected to ultrasonication treatment to penetrate functionalized-CNC into the SYP. A vacuum pressure treatment for air pocket removal and functionalized-CNC impregnation followed this. After treatment, the wood was dried and underwent mechanical testing following ASTM D1037 and ASTM D2339 standards. Delignified and functionalized-CNC impregnated SYP increased the modulus of rupture (MOR) by 68% and the modulus of elasticity (MOE) by 72%. Localized MOE maps were also generated under an atomic force microscope (AFM) to characterize the material. It was found that the areas with a CNC presence have a significantly greater elasticity modulus (<20 GPa) compared to the rest of the region consisting of SYP (3.00 - 8.55 GPa) using the Hertzian Contact model. The results support a novel methodology to improve the mechanical properties of wood delignification and functionalized CNC impregnation.Item Experimental evaluation of the mechanical properties of recycled high-density polyethylene (rHDPE) blended with talc filler, for engineering applications(Montana State University - Bozeman, College of Engineering, 2023) Malyuta, Daniel Aaron Isilyumu; Chairperson, Graduate Committee: Kirsten Matteson; This is a manuscript style paper that includes co-authored chapters.The extensive use of thermoplastic products, particularly high-density polyethylene (HDPE), has led to significant plastic waste, posing environmental threats. To manage thermoplastic waste, recycling is the preferred method; however, this has not been wholly effective due to technological and economic challenges and limitations. Large-scale applications of recycled HDPE (rHDPE) can incentivize recycling and create new revenue streams. HDPE is a well-established thermoplastic for engineering applications, and components made of HDPE have desirable properties such as high strength-to-weight ratio, ease of processing, availability, low cost, and excellent chemical and corrosion resistance. With concerns about the fate of plastics at end-of-life, there is a growing interest in strategies to utilize rHDPE in place of virgin HDPE (vHDPE). This study focused on investigating the mechanical and thermal properties of rHDPE-talc blends across various talc filler contents and temperatures, and across four recycling generations, as understanding these properties is crucial for application. Following ASTM standards, tests for tensile strength, elastic modulus, storage modulus, nominal yield stiffness, nominal yield strain, impact strength, and melt flow index were performed. Dynamic mechanical analysis and differential scanning calorimetry were also carried out. Results show that talc content and temperature affect tensile strength, elastic modulus, nominal stiffness, yield strain, impact strength, and storage modulus. Melting temperature decreased while crystallinity increased with talc filler content increase. Compared to neat HDPE and in most cases vHDPE-talc blends, rHDPE-talc blends perform better. Response Surface Methodology was applied using the Central Composite Design statistical experimental design approach to further study the stiffness and strength of rHDPE as functions of temperature and talc filler content. It revealed significant correlations for practical applications. Increasing the number of thermal reprocessing cycles decreased tensile strength, elastic modulus, impact strength, and storage modulus, while nominal yield strain and melt flow index increased. Crystallinity and melting temperature minimally decreased with increased thermal reprocessing cycles. Despite these changes, most of the properties of both the neat rHDPE and its talc blends remain comparable to the virgin counterparts, even after the fourth recycling generation. This implies that the recycled materials can be suitable for use in existing applications of vHDPE.Item Preliminary mechanical testing of continuous stretch broken carbon fiber cured laminates(Montana State University - Bozeman, College of Engineering, 2022) Loomis, Noah Michael; Chairperson, Graduate Committee: Dilpreet S. BajwaApplication of carbon fiber prepregs in cost-sensitive, high-volume structural applications are limited due to the difficulty to form deep drawn parts. Stretch broken carbon fiber (SBCF), is an aligned discontinuous form of carbon fiber that is under development at Montana State University (MSU). The improved SBCF has the potential to increase the formability of these carbon fiber prepregs. However, any formability benefits of SBCF would be limited if the laminates have reduced mechanical properties when compared to conventional continuous carbon fiber composites. Two studies were performed to evaluate the mechanical potential of MSU SBCF. The first study compared the 0° unidirectional tensile mechanical properties of continuous carbon fiber and SBCF laminates both manufactured by MSU at ambient room temperature. Materials included Hexcel IM7-G continuous carbon fibers and SBCF using a Solvay Cytec 977-3 resin as the matrix. The results of the study show that the unidirectional tensile mechanical properties of stretch broken carbon fiber laminates did not significantly differ from the continuous laminates. Normalized for a fiber volume of 60%, the MSU continuous and stretch broken materials had nearly equivalent tensile properties, and their properties were within 15% of stated values for commercial material. Failure modes and strain to failure were nearly identical between the two types of laminates. The second study compared tensile, compression and shear mechanical properties of commercial continuous carbon fiber and MSU SBCF laminates at ambient room temperature. Materials included Hexcel IM7-G carbon fiber with Hexcel 8552 resin as the matrix. The preliminary results of the study showed that the fiber dominated mechanical properties of stretch broken carbon fiber laminates were slightly lower when compared to the commercial continuous laminates. Fiber dominated mechanical properties had at least a 17% loss of strength while matrix dominant mechanical properties were found to be equivalent and unchanged.Item Fiber shape effects on the compressive strength of unidirectional carbon fiber composites: a computational study(Montana State University - Bozeman, College of Engineering, 2020) Clarke, Ryan; Chairperson, Graduate Committee: David A. MillerThe tensile strength tends to be much higher than the compressive strength for carbon fiber reinforced polymer composites because of a change in failure modes. Current research activities are looking at novel precursors for reducing overall costs of carbon fiber production. The potential cost savings in new precursor carbon fiber make it economically feasible to use in large structural components. Some fiber precursors and manufacturing methods produce carbon fibers that have a kidney-shaped cross-section whereas traditional carbon fiber is circular. The aim of this study is to investigate the differences in compressive failure responses between fiber shapes in carbon fiber composites. A finite element micromechanical model was developed in ABAQUS of a single carbon fiber embedded in a square matrix with periodic boundary conditions. Two fiber cross-sectional geometries were examined: circular and kidney shaped. Three factors that affect the compressive failure response of carbon fiber reinforced polymers were investigated. These include fiber misalignment, volume fraction, and multiaxial loading. The results showed negligible differences between the compressive failure response of fibers with different cross-sectional shapes. Compressive strength was shown to have a decaying sensitivity to increasing fiber misalignment. Decreasing the volume fraction did decrease the compressive strength but also increased the compressive failure strain. In addition, adding in-plane shear loads proved detrimental to the compressive load-carrying capacity of a composite structure. This research showed minimizing fiber misalignment in manufacturing processes is only beneficial for high tolerance processes. In addition, decreasing volume fraction could be beneficial for highly flexible structures. Finally, the results demonstrated the need to minimize multiaxial loading for optimal composite compressive response.Item Value-added composite bioproducts reinforced with regionally significant agricultural residues(Montana State University - Bozeman, College of Engineering, 2018) Solle, Matthew Arthur; Chairperson, Graduate Committee: Cecily Ryan; Jesse Arroyo, Stephan Warnat, Macdonald Burgess and Cecily Ryan were co-authors of the article, 'Evaluation of locally sourced agricultural residue in composites' submitted to the journal 'Composites science and technology' which is contained within this thesis.Biopolymers, such as polyhydroxybutyrate-co-hydroxyvalerate (PHBV), combined with natural fiber into biocomposites have potential as sustainable alternatives to traditional plastics and composites for which recycling is challenging. The addition of natural fibers, such as hemp, kenaf, and jute can increase the stiffness and strength of biopolymers at low weight and cost without compromising composite biodegradability. Because production of many natural fibers is limited by climate or geography, local and regional fiber sources collected as residues from agricultural crop production have potential to further reduce composite environmental impact by reducing embodied energy related to transportation and fiber cultivation. In this study four agricultural residue fibers (AF) were assessed: (i) hollow stem wheat, (ii) solid stem wheat, and (iii) barley as regionally significant food crop residues compared to (iv) hemp residue from seed and oil production as an industrially relevant control. These fibers were compounded into PHBV composites at fiber weight fractions of 0%, 10%, 20%, and 30%. Two fiber compatibilizing treatments were investigated for their potential to enhance the mechanical performance of AF-PHBV composites: (i) silane vapor deposited at room temperature and (ii) PHBV grafted to the fibers using reactive extrusion (gPHBV). Mechanical properties including flexural modulus and ultimate flexural strength were used to evaluate the impact of fiber fraction and treatments on biocomposites. Statistical analysis from our design of experiments indicated that some combinations of fiber, weight fraction, and treatment clearly outperformed others. In particular, samples with 30% silane treated hemp had the highest modulus and high flexural strength, while 30% gPHBV hemp had high modulus and the highest strength. Among residue composites, hollow stem wheat is most comparable to hemp, with similar modulus but lower flexural strength in treated high fiber samples. Solid stem wheat and barley composites generally had lower modulus, lower strength, and less consistent mechanical properties. Increasing fiber fraction consistently increased flexural modulus. Grafted samples had inconsistent flexural strength due to deleterious effects to the gPHBV matrix, as observed with scanning electron microscopy and differential scanning calorimetry. The mechanical properties of the different AF-composites occupy a similar application space, indicating potential for robust composite processing using AF.Item Guided inquiry labs in AP Physics(Montana State University - Bozeman, College of Letters & Science, 2019) Ryerson, Michael; Chairperson, Graduate Committee: Greg FrancisThis study was performed to determine the impact of guided inquiry experiments on students in AP Physics C: Mechanics. Qualitative and quantitative data were gathered to answer the following questions: What are the effects of introducing guided inquiry experiments on student enjoyment of physics? The following secondary questions were also investigated: Does conducting guided inquiry experiments improve student retention of course material? Does conducting guided inquiry experiments improve students' ability to write about science? Two sections were used as a treatment and non-treatment group. As one group conducted guided inquiry experiments, the other performed traditional experiments. After the first round of treatment, the groups were swapped. Surveys and interviews were conducted before, during, and after both rounds of treatment. Results of the study indicated that students who received the treatment early in the year enjoyed guided inquiry more and became more comfortable with independence than the group who received the treatment in the second semester. Results showed no significant impact on retention of course material or science writing ability. It is hypothesized that those students who formed good experimental habits by performing inquiry early in the year were better able to adapt and enjoy the experiments than those who started out in the non-treatment group performing traditional experiments.Item Developments in electrically conductive bio-composites for use in additive manufacturing(Montana State University - Bozeman, College of Engineering, 2019) Arroyo, Jesse Whitney; Chairperson, Graduate Committee: Cecily Ryan; Cecily Ryan was a co-author of the article, 'Incorporation of carbon nanofillers tunes mechanical and electrical percolation in PHBV:PLA blends' in the journal 'Polymers' which is contained within this thesis.With the growth of rapid production methods, such as additive manufacturing, petroleum derived plastics are becoming ever more prevalent in consumer homes and landfills. As the industry grows, research into a more circular approach to designing and using materials is critical to maintaining sustainability. Bioplastics such as poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and poly(lactic acid) (PLA) provide material properties comparable to petroleum derived plastics and are becoming more common in the additive manufacturing field. Biobased fillers, such as bio-derived cellulose, lignin byproducts, and biochar, can be used to modify the thermal, mechanical, and electrical properties of polymer composites. Biochar (BioC), in particular, is of interest for enhancing thermal and electrical conductivities in composites, and can potentially serve as a bio-derived graphitic carbon alternative for certain composite applications. In this work, we investigate a blended biopolymer system: PLA/PHBV, and addition of carbon black (CB), a commonly used functional filler as a comparison for Kraft lignin-derived BioC. We present calculations and experimental results for phase-separation and nanofiller phase affinity in this system, indicating that the CB localizes in the PHBV phase of the immiscible PHBV:PLA blends. The addition of BioC led to a deleterious reaction with the biopolymers, as indicated by blend morphology, differential scanning calorimetry showing significant melting peak reduction for the PLA phase, and a reduction in melt viscosity. For the CB nanofilled composites, electrical conductivity and dynamic mechanical analysis supported the ability to use phase separation in these blends to tune the percolation of mechanical and electrical properties, with a minimum percolation threshold found for the 80:20 blends of 1.6 wt.% CB. At 2% BioC (approximately the percolation threshold for CB), the 80:20 BioC nanocomposites had a resistance of 3.43x10 8 Omega as compared to 2.99x10 8 Omega for the CB, indicating that BioC could potentially perform comparably to CB as a conductive nanofiller if the processing challenges can be overcome. Investigations into alkaline and dealkaline lignin sources have shown that alkaline lignin experiences a significant effect on the thermal stability of PHBV eluding that alternate sources of lignin may provide a solution to the processing challenges mentioned. This work has helped to develop a understanding of the factors that aid in creating sustainable materials sourced from PLA,PHBV, and BioC.Item The elastic properties of bone by ultrasound(Montana State University - Bozeman, College of Engineering, 1985) LaMont, Donald Thompson; Chairperson, Graduate Committee: Michael K. WellsItem Engineering properties of some Montana soil series(Montana State University - Bozeman, College of Agriculture, 1974) Volk, William Pius