Mukund Sibi - Thesis Committee

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Browsing Mukund Sibi - Thesis Committee by browse.metadata.program "Coatings and Polymeric Materials"

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    High Performance Bio-Based Thermosets for Composites and Coatings
    (North Dakota State University, 2016) Ambeg Paramarta, Adlina
    In the recent decade, there has been increasing interest in using renewable feedstocks as chemical commodities for composites and coatings application. Vegetable oils are promising renewable resources due to their wide availability with affordable cost. In fact, the utilization of vegetable oils to produce composite and coatings products has been around for centuries; linseed oil was widely used for wide variety of paints. However, due to its chemical structure, the application of vegetable oils for high-performance materials is limited; and thus chemical modification is necessary. One of the modification approaches is by substituting the glycerol core in the triglycerides with sucrose to form sucrose esters of vegetable oil fatty acids, in which this resin possesses a higher number of functional group per molecule and a more rigid core. In this research, thermosets of highly functionalized sucrose esters of vegetable oils were developed. Two crosslinking methods of epoxidized surcrose soyate (ESS) resins were explored: direct polymerization with anhydride moieties for composite applications and Michael-addition reaction of acrylated-epoxidized sucrose soyate (AESS) for coatings applications. In the first project, it was shown that the reaction kinetics, thermal and mechanical properties of the materials can be tuned by varying the molar ratio between the epoxide and anhydride, plus the type and amount of catalyst. Furthermore, the toughness properties of the ESS-based thermosets can be improved by changing the type of anhydride crosslinkers and incorporating secondary phase rubbers. Then, in the second system, the epoxy functionality in the ESS was converted into acrylate group, which then crosslinked with amine groups through the Michael-addition reaction to produce coatings systems. The high number of functional groups and the fast reactivity of the crosslinker results in coatings that can be cured at ambient temperature, yet still possess moderately high glass transition temperatures.
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    Highly Functionalized Thermosets from Renewables for Composites and Coatings Applications
    (North Dakota State University, 2017) Yu, Arvin
    Renewable sources have attracted attention due to their affordable cost and wide availability. Vegetable oils are renewable sources that have been extensively studied as potential replacement for petroleum derived chemicals. However, vegetable oils tend to produce soft materials with modest properties due to their chemical structure. Consequently, their modifications have been studied to develop high performance materials with improved properties. One of the modifications involves substituting the glycerol core with sucrose to increase the functionality per molecule. Another approach is converting the less reactive internal carbon-carbon double bonds with the more reactive epoxy groups, which permits access to a variety of crosslinking pathways. Epoxidized sucrose soyate (ESS) is a sucrose ester fatty acid (SEFA), which was epoxidized via the Prilezhaev reaction. ESS has a rigid sucrose core and epoxy functionalized fatty acid side chains. The high functionality of ESS was exploited and it was converted to methacrylated and carbonated resins. The methacrylated resins were applied in producing themosets by free-radical polymerizations while the carbonated resins were studied in step-growth polymerizations. Several studies were done to exploit the high functionality of the methacrylated resins: reduction of the viscosity while increasing crosslinkable moieties, introduction of ductility, structure-property relationships, and investigation of resin versatility in photocurable systems. Meanwhile, the carbonated resins were used to form non-isocyanate polyurethane (NIPU) coatings via cyclic carbonate-amine reactions. Overall, the highly functionalized bio-based thermosets showed very promising properties for composites and coatings applications.
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    Polymers and Coatings Derived From Novel Bio-Based Vinyl Ether Monomers
    (North Dakota State University, 2018) Kalita, Deep Jyoti
    To fulfill the demand for household, industrial, light weight transportation, health, and cosmetic products etc., production of polymeric materials has been increasing every year. However, limited resource of fossil fuel is threatening the sustainability of the raw materials used to produce these products. These products have very low to no biodegradability, thereby staying in the ecosystem for long time causing serious threats. Increasing environmental concerns and strict regulations has made renewable based materials suitable for the development of environmental friendly polymers with sustainability. Novel plant oil based vinyl ether (POVE) monomers were derived from plant oil such as soybean, linseed and camelina oil. Polymers varying in molecular weight (MW) were derived from these monomers and studied for air-drying coatings. Study of the coating and free film properties showed that at a given MW, Tensile (Young’s modulus, and tensile strength), viscoelastic (Tg, XLD), physical (hardness, solvent resistance, and impact resistance) properties increased with increasing unsaturation in the parent PO. Polymers derived from distilled POVE monomers resulted essentially colorless poly(POVEs) which were evaluated as a binder for artist paint in comparison to linseed oil. Colorless poly(POVE)s showed significantly faster dry/cure along with dramatically lower yellowness than linseed oil. Novel, vinyl ether monomers, were also synthesized from cardanol (CEVE) and eugenol (EEVE) and coatings produced from their homopolymers and copolymers with cyclohexyl vinyl ether were studied in comparison to commercial alkyds. Glass transition temperatures of these homopolymers were increased with CHVE incorporation. However, incorporation of 25% CHVE resulted in cured coatings and free films with better mechanical, viscoelastic and physical properties than commercial alkyds. Incorporation of CHVE > 50wt.% in the copolymer resulted in low crosslinked networks with reduced properties such as percent elongation, chemical resistance and impact resistance. Epoxidized poly(EEVE) resins varying in percent epoxide (30%, 50% and 70%) were synthesized and studied for two component amine cured coatings in comparison to BPA based epoxy resin. Results obtained from high throughput experimentation showed the ability of Epoly(EEVE) resins with 50% or higher epoxide to form harder, higher crosslinked coatings with tunability based on type of curative than BPA based resin.