{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,5]],"date-time":"2026-09-05T06:06:33Z","timestamp":1788588393577,"version":"build-2803163510"},"reference-count":47,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2023,1,11]],"date-time":"2023-01-11T00:00:00Z","timestamp":1673395200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"German Federal Ministry for Economic Affairs and Climate Action (BMWK)"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Bio-based alternatives for petroleum-based thermosets are crucial for implementing sustainable practices in fiber-reinforced polymer composites. Therefore, the mechanical properties of diglycidyl ether of bisphenol a (DGEBA) cured with either l-arginine, l-citrulline, \u03b3-aminobutyric acid, l-glutamine, l-tryptophan, or l-tyrosine were investigated to determine the potential of amino acids as bio-based curing agents for epoxy resins. Depending on the curing agent, the glass transition temperature, Young\u2019s modulus, tensile strength, and critical stress intensity factor range from 98.1\u00a0\u2218C to 188.3\u00a0\u2218C, 2.6\u00a0GPa to 3.5\u00a0GPa, 39.4\u00a0MPa to 46.4\u00a0MPa, and 0.48\u00a0MPam0.5 to 1.34\u00a0MPam0.5, respectively. This shows that amino acids as curing agents for epoxy resins result in thermosets with a wide range of thermo-mechanical properties and that the choice of curing agent has significant influence on the thermoset\u2019s properties. After collecting the results of dynamic mechanical analysis (DMA), tensile, flexural, compression, and compact tension tests, the functionality f, cross-link density \u03bdC, glass transition temperature Tg, Young\u2019s modulus ET, compression yield strength \u03c3Cy, critical stress intensity factor in mode I KIC, fracture energy GIC, and diameter of the plastic zone dp are correlated with one another to analyze their inter-dependencies. Here, the cross-link density correlates strongly positively with Tg, ET, and \u03c3Cy, and strongly negatively with KIC, GIC, and dp. This shows that the cross-link density of DGEBA cured with amino acids has a crucial influence on their thermo-mechanical properties and that the thermosets considered may either be stiff and strong or tough, but hardly both at the same time.<\/jats:p>","DOI":"10.3390\/polym15020385","type":"journal-article","created":{"date-parts":[[2023,1,12]],"date-time":"2023-01-12T03:11:02Z","timestamp":1673493062000},"page":"385","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":27,"title":["Amino Acids as Bio-Based Curing Agents for Epoxy Resin: Correlation of Network Structure and Mechanical Properties"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9948-3310","authenticated-orcid":false,"given":"Florian","family":"Rothenh\u00e4usler","sequence":"first","affiliation":[{"name":"Department of Polymer Engineering, University of Bayreuth, Universit\u00e4tsstra\u00dfe 30, 95447 Bayreuth, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5985-2628","authenticated-orcid":false,"given":"Holger","family":"Ruckdaeschel","sequence":"additional","affiliation":[{"name":"Department of Polymer Engineering, University of Bayreuth, Universit\u00e4tsstra\u00dfe 30, 95447 Bayreuth, Germany"},{"name":"Neue Materialien Bayreuth GmbH, Gottlieb-Keim-Stra\u00dfe 60, 95448 Bayreuth, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,1,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Sch\u00fcrmann, H. 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