17007 research outputs found
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Audience Chatting
No full textAudience members talking at the reception after the 2025 Gene DeGruson Lecture.https://digitalcommons.pittstate.edu/sweatt_lecture/1081/thumbnail.jp
Exploring Sustainable Biopolyesters: Synthesis from 1,4-Butanediol and Aliphatic Diacids
No full textBiobased polyesters were synthesized from 1,4-butanediol and a series of aliphatic dicarboxylic acids, namely succinic acid, adipic acid, and sebacic acid using melt polycondensation. The resulting polymers poly(butylenesuccinate) (PPeS), poly(butylene adipate) (PPeA), and poly(butylene sebacate) (PPeSe) were characterized with intrinsic viscosity, nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis(DMA) and tensile testing. All the polymers had weight-average molecular weight of over 50,000 g/mol and melting temperature (Tm) ranging from 50 oC to 116 oC, PPeA exhibited a lower melting temperature due to semicrystalline structure and rapid crystallization. The even-even effect was observed, contributing to an increased tensile strength of PPeA. All the polymers exhibit good thermal stability, mechanical properties, and tensile properties compared to polyethylene. These biobased and potentially biodegradable polyesters appear to be promising for practical applications like packaging, biomedical materials, and environmentally friendly plastics
Effect of Crosslinker Variations on the Mechanical, Thermal, and Solvent Resistance Performance of Bio-Based Polyurethane Adhesives
No full textThis research aims to develop sustainable polyurethane adhesives with enhanced mechanical, thermal, and chemical properties by synthesizing two new crosslinkers: DEA, derived from Ethanolamine and Dimethyl benzene-1,4-dicarboxylate, and DPA, synthesized from 3-Amino-1-propanol and Dimethyl benzene-1,4- dicarboxylate. These crosslinkers were reacted with soybean oil polyol (SOP) and methylene diphenyl diisocyanate (MDI) to create adhesive samples with varying concentrations of crosslinkers (5, 10, 15, and 20 wt.% for DEA and 5, 10, 15, 20, and 25 wt.% for DPA), which were then cured at room temperature (RT) and 90C to examine the effects of thermal curing. FTIR analysis confirmed the successful formation of urethane linkages between the crosslinkers, polyol, and isocyanate. Tensile strength testing revealed that the adhesion strength of the adhesives increased with the crosslinker content up to an optimum level, with peak values of 6.77 MPa for DEA-15 wt.% and 6.86 MPa for DPA-20 wt.%, after which the adhesion strength decreased with higher concentrations. Gel swell analysis showed that DEA-based adhesives exhibited minimal swelling in both water and toluene, indicating a stable and well-formed crosslinked network. DPA-based adhesives, while exhibiting slightly lower gel content in toluene, still demonstrated strong solvent resistance, particularly in water, where the swelling degree was notably reduced. Hardness testing and Differential Scanning Calorimetry (DSC) further indicated that crosslinking significantly increased the rigidity and thermal stability of the adhesives, especially in heat-cured samples. These findings suggest that polyurethane adhesives with optimized crosslinker content, tailored for specific applications, offer strong potential for industrial use, particularly in applications requiring good mechanical strength, solvent resistance, and thermal stability
Optimizing Bio-Based Polyurethane Coatings for Enhanced Mechanical Strength and Hydrophobicity through Glycerol and HMDS Modification
No full textThis study focuses on the development of durable, eco-friendly bio-based polyurethane (PU) coatings as sustainable alternatives to petroleum-based products. The research aims to reduce environmental impact while maintaining high performance in coating applications. Bio-based PU coatings were synthesized using soybean oil polyol (SOP), glycerol (GLY) as a crosslinker, and methylene diphenyl diisocyanate (MDI). The study was conducted in two phases: first, optimizing the glycerol content to enhance mechanical properties, and second, incorporating hexamethyldisilane (HMDS) to improve hydrophobicity and chemical resistance. In the first phase, PU coatings were prepared with varying weight percentages (wt.%) of glycerol (0, 5, 10, 15, and 20), and mechanical testing revealed that 10 wt.% GLY provided the best mechanical strength. In the second phase, the optimized formulation was further modified by adding HMDS in different wt.% (10, 20, 30, 40, and 50). The results indicated that 10 wt.% HMDS offered the best tensile strength, but higher concentrations of HMDS negatively affected crosslinking and homogeneity, leading to reduced mechanical performance. FT-IR analysis confirmed the formation of urethane bonds, while DSC and TGA analyses demonstrated the thermal stability of the coatings. Additionally, gel content and degree of swelling tests were conducted to evaluate the crosslinking density. The findings suggest that bio-based PU coatings with optimized glycerol and HMDS content can serve as effective, sustainable alternatives for industrial coating applications, offering a balance of mechanical strength, chemical resistance and environmental benefits
Treatment of Germans at Kansas State Manual Training Normal School
No full textWhen the United States of America declared war on Germany on April 6, 1917, the nation made enemies not only with Germany, but with German culture. Pro-German sentiments were viewed with suspicion and people were looked at as a traitor or a spy. With the suspension of constitutional rights under the Espionage and Sedition Acts, Americans that expressed an opinion against the war effort became criminals overnight. The crusade against the anti-American sentiment enveloped all aspects of life; schools were no longer allowed to teach German, German towns and streets were renamed, speaking German in public became taboo. This wave of Americanization was felt across the nation, including universities and normal schools. The same level of anti-German sentiment was not seen everywhere, and this paper examines Kansas State Manual Training Normal School and how it compares with other schools. Through renaming, German language, harassment, size, and ethnic diversity this paper argues the Kansas State Normal School faced little to no German persecution
A Student-Led Usability Study of the Pittsburg State University Website
No full textIn this study, we aimed to improve the user experience of the Pittsburg State University (PSU) website by analyzing problem areas that deter prospective and current students. We specifically investigated scholarship application processes, the usability of existing GUS and Classic portals, and the steps needed to access transcripts. Through moderated usability sessions and affinity diagrams, we identified recurring pain points and thematic user frustrations, such as outdated pages in the redesign and insufficient site navigation. We found that while the redesign resolved some issues, it introduced new navigational concerns and did not fully address critical functionality. Using Figma, we developed user flows and redesigned targeted portions of the site, focusing on clearer labeling, streamlined navigation. Our proposals aim to reduce frustration, increase user engagement, and streamline tasks for both new and current PSU community members. We seek to spark discussions on collaborative efforts to continually enhance the website\u27s performance and user satisfaction
Regulating Lignin-Based Epoxy Vitrimer Performance by Fine-Tuning the Lignin Structure
No full textLignin is the second most abundant lignocellulosic biomass, and as a natural polymer, it shows great potential in preparing functional materials to meet the demand for green/sustainable development. Unfortunately, the inherent heterogeneity of lignin largely limits its applications. Furthermore, the effect of the lignin structure on the performance of the final materials has seldom been investigated. In this work, a totally biobased dynamic cross-linked vitrimer with up to 70% lignin content was successfully prepared from epoxidized fractionated lignin and sebacic acid without additional chemical modifications. The lignin structure effect on the performance of the resultant lignin-based epoxy vitrimers (LEVs) was systematically investigated. The experimental results show that the phenolic hydroxyl content and the ratio of flexible to rigid linkages in lignin have strong correlations with the tensile strength, toughness, self-repair ability, and reprocess ability of the resultant LEVs. Meanwhile, the molecular weight and the S/G ratio of lignin show strong correlations with the thermal properties of the resultant materials. This study not only presents a fundamental study regarding the relationships between lignin properties, and the resultant LEVs have great potential applications as advanced packaging materials for light-sensitive commodities due to the inherent UV resistance of lignin
High-Strength, Self-Healing, Recyclable, and Catalyst-Free Bio-Based Non-Isocyanate Polyurethane
No full textNon-isocyanate polyurethanes (NIPUs) from renewable resources have attracted wide attention because of their remarkable benefits to sustainable development and green production. In this work, a strong, self-healing, and catalyst-free NIPU(ECMP)was prepared based on the hyperbranched bio based cyclic carbonate (Ec-MTDA) synthesized through catalytic carbonization of 1,8-menthanediamine (MTDA) and CO2.The hyperbranched and rigid structures of ECMP enable improved mechanical properties that ahigh tensile strength of up to 34.9 MPa can be achieved. Benefiting from the dynamic trans esterification reaction between the carbamate and hydroxyl groups, ECMP presents favorable self-healing, reprocessing properties, and shape memory. Notably, 91% of the original tensile strength can be recovered after self-healing behavior. In addition, abundant polar groups provide excellent adhesion properties for ECMP with a high shear strength of 7.09 MPa. This study provides a promising strategy for the design of bio-based NIPUs, which broadens their applications in printing, furniture, packaging, and other industries
NiMn2O4 Nanosheet/Carbon Nanotube Composites for Aqueous Zinc-lon Batteries
No full textDue to the continuous depletion of lithium resources and the security risks of organic electrolytes such as combustion and explosion, there is an imminent requirement to develop a type of energy accumulation system to adapt to the progression and progress of society. Zinc-ion batteries using aqueous electrolyte have the advantages of high safety, low cost, and environmental friendliness, which make them an ideal alternative to lithium-ion batteries as a next-generation energy storage system. Among the zinc-ion battery cathode materials, manganese-based materials and carbon materials occupy the main positions, respectively. Among them, nickel manganate (NiMn2O4) nanosheets and carbon nanotubes (CNTs) as active materials have received extensive attention. The CNTs could provide electronic conductive channels and NiMn2O4 nanosheets supply more active points for electrochemical reactions. The carbon shell with a porous structure also improves the electron transport and ionic conduction processes, so that the nickel manganate/carbon nanotube (NiMn2O4/CNTs) nanocomposites obtained a high specific capacitance of 333.6 mAh/g at a current density of 0.2 A/g. After 500 cycles at a current density of 0.5 A/g led to a high specific capacity of 73.6 mAh/g, it was shown that the material exhibits excellent comprehensive electrochemical properties. This synergistic strategy of combining structural design and electrochemical activation in NiMn2O4/CNTs nanocomposites can be a reference for other manganese-based cathode materials
Catalyst Selectivity in the Addition of Hydroxybenzoic Acids to Glycidyl Phenyl Ether
No full textEpoxides are an important class of reagents in organic chemistry which react with a variety of nucleophiles. Strong nucleophiles add to epoxides at the least substituted carbon via a SN2 mechanism. However, under acidic conditions nucleophilic addition is at the most substituted carbon via a SN1 mechanism. Included within this class of reactions is the addition of carboxylic acids or phenols to epoxides using tetrabutylammonium bromide as the catalyst. These reactions are straight forward and give high yields of the product. However, previous work in our lab showed a faster reaction rate of benzoic acid addition to an epoxide with tetrabutylammonium fluoride. Due to this result, we were interested in the effect of catalyst on the selectivity of the reaction. To glycidyl phenyl ether was added 4-hydroxybenzoic acid, 3-hydroxybenzoic acid or salicylic acid using a tetrabutylammonium halide (F, Cl, Br, or I) catalyst. After the reaction, the products were analyzed by IR spectroscopy and the product ratio was determined using proton NMR spectroscopy. The resulting IR spectra and ratio of products from these studies will be reported