17007 research outputs found
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McCray Hall
No full textColor Kodak photograph of McCray Hall. A building that may be Willard Hall stands in the backgroundhttps://digitalcommons.pittstate.edu/mccraybuilding/1085/thumbnail.jp
McCray, Snow
No full textBlack and white photo of McCray in the snowhttps://digitalcommons.pittstate.edu/mccraybuilding/1094/thumbnail.jp
Eads, Ronnie D. Collection, 2020-2024
Get PDFA small collection of poetry written by Ronnie D. Eads, a graduate of Pittsburg State University.https://digitalcommons.pittstate.edu/fa/1442/thumbnail.jp
Russ Hall - Front Entrance
No full textColor photo of the front entrance of Russ Hall as seen from the sidewalk.https://digitalcommons.pittstate.edu/russbuilding/1115/thumbnail.jp
Russ Hall - Scanned Negatives
No full textScanned negatives of Russ Hall\u27s front entrance and people outside the building.https://digitalcommons.pittstate.edu/russbuilding/1160/thumbnail.jp
Russ Hall - Front Entrance
No full textBlack and white photo of the Russ Hall front entrance from an unknown date (of note is the fallout shelter sign is still about the doors). People are walking or sitting in front of the building. Possibly taken in the 1950s.https://digitalcommons.pittstate.edu/russbuilding/1175/thumbnail.jp
MULTIPLE EXEMPLAR AND MASTERY CRITERIA FOR STIMULUS GENERALIZATION
Get PDFThis study examines the inclusion of multiple exemplars in mastery criteria and its effect on maintenance and generalization. This study examines early intervention with children aged 3-6 diagnosed with ASD. The utilization of three exemplars in mastery criteria compared to one exemplar lead to greater generalization, but generalization remined low across both conditions
ECO-FRIENDLY POLYESTER VITRIMER: ENHANCED STRETCHABILITY, SELF-HEALING, AND REPROCESSABILITY THROUGH DYNAMIC COVALENT CROSSLINKS VIA MELT-POLYCONDENSATION
Get PDFDynamic covalent polymer networks offer new possibilities for designing sustainable polyester vitrimers owing to their excellent reprocessability and malleability; however, maintaining the high performance of the adaptable network with amazing healing properties remains a challenge. Therefore, the proposed approach considers the one-pot synthetic strategy to fabricate highly stretchable polyester vitrimer networks via condensation polymerization of different aliphatic diacids which are glutaric acid, pimelic acid, azelaic acid with 1,4-butanediol in the presence of glycerol and dithiodicarboxylic acids as the curing agent and dynamic covalent crosslinkers. The synthesized polyester network with simultaneous disulfide metathesis and carboxylate transesterification exhibited vitrimeric behavior which can alter the topologies through the reversible bond exchange, displaying high elasticity, reprocessability, and self-healable properties. Gel fraction experiments, rheological studies, and self-welding ability demonstrated the dynamicity of the polyester network. Thermomechanical characteristics and vitrimeric features were analyzed by dynamic mechanical analysis, showing that stress relaxes very rapidly and has relaxation times ranging from 72 s to 288 s (at 150 °C) and 870 s to 1590 s (at 100 °C), while 100% self-healing efficiency was achieved when thermally triggered at 50 oC within 5 h. Moreover, the developed polyester vitrimer demonstrates extensive elongation (up to 2000%) properties depending on the dithiocrosslinker chain length, crosslink density, and excellent reprocessability. Even after reprocessing, the reprocessed vitrimers maintained almost the same mechanical characteristics and good reconfigurability, leveraging the dual bond-exchange mechanism. Briefly, the simplicity of the polycondensation process, application, and processing of this vitrimer can help direct the development of a new covalently adaptive elastomer with enhanced sustainability and performance
BIO-BASED POLYURETHANE FILMS: EFFECT OF HYDROXYL NUMBERS ON THE PROPERTIES OF THE POLYURETHANE FILMS
Get PDFIn today\u27s world, there\u27s a growing shift towards adopting eco-friendly and sustainable materials in response to pressing environmental concerns. Among the key polymeric materials utilized in various industries, polyurethanes stand out, being widely employed in the manufacture of everyday essentials. However, the conventional method of producing polyurethanes relies heavily on hazardous and fossil fuel-derived substances, presenting significant environmental challenges. To address this issue, there\u27s a critical need to substitute petroleum-based materials with more sustainable alternatives. In our research, we focused on utilizing limonene, a compound found in citrus fruit peels such as lemon and orange, and geraniol, extracted from rose and citronella oils. Through thiol-ene click reactions, we synthesized several thiols by reacting limonene with 2-mercaptoethanol and 1-thioglycerol. Geraniol reacted with 2-mercaptoethanol. This process involved the conversion of the C=C bonds present in limonene and geraniol when combined with various thiol compounds. Subsequently, the obtained thiols underwent treatment with Methylene Diisocyanate (MDI), followed by the curing of polyurethane films at temperatures of 70°C and 100°C. Furthermore, we introduced soybean polyol into the mix in varying weight ratios to enhance the mechanical properties of the films. Through this approach, we aimed to investigate the influence of increasing hydroxyl group content on the properties of polyurethane films. Our study not only demonstrates a sustainable method for synthesizing polyurethane films but also highlights the effectiveness of thiol compounds in the conversion process. To evaluate the structural morphology of the polyurethane films, we employed Fourier Transform Infrared Spectroscopy (FTIR), and Nuclear Magnetic Resonance (NMR), while mechanical properties were assessed through tensile and hardness tests. Additionally, we analyzed the thermal behavior of the films using thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). Overall, our research contributes to the development of environmentally friendly alternatives in polymer synthesis and offers insights into improving the performance of polyurethane materials