{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,18]],"date-time":"2026-07-18T16:20:21Z","timestamp":1784391621137,"version":"3.55.0"},"reference-count":46,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2025,6,27]],"date-time":"2025-06-27T00:00:00Z","timestamp":1750982400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Centre for Research and Development (Poland)","award":["INNOGLOBO\/3\/76\/Eko-Ognioodporne Panele Izolacyjne\u2014EOPI\/2023"],"award-info":[{"award-number":["INNOGLOBO\/3\/76\/Eko-Ognioodporne Panele Izolacyjne\u2014EOPI\/2023"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Sheep wool is a natural fiber from various sheep breeds, mainly used in clothing for its insulation properties. It makes up a small share of global fiber production, which is declining as synthetic fibers replace wool and meat farming becomes more profitable. Wool from slaughter sheep, often unsuitable for textiles, is treated as biodegradable waste. The aim of the study was to develop a fully biodegradable composite of natural origin from a polylactide (PLA) matrix reinforced with sheep wool and to select the optimal modifications (chemical) of sheep wool fibers to obtain modified properties, including mechanical properties. The behavior of the composites after exposure to aging conditions simulating naturally occurring stimuli causing biodegradation and thus changes in the material\u2019s performance over its lifespan was also examined. Dynamic thermal analysis was used to describe and parameterize the obtained data and their variables, and the mechanical properties were investigated. The research culminated in a microscopic analysis along with changes in surface properties. The study demonstrated that wool-reinforced composites exhibited significantly improved resistance to UV degradation compared to pure PLA, with samples containing 15% unmodified wool showing a 54% increase in storage modulus at 0 \u00b0C after aging. Chemical modifications using nitric acid, iron compounds, and tar were successfully implemented to enhance fiber\u2013matrix compatibility, resulting in increased glass transition temperatures and modified mechanical properties. Although wool fiber is not a good choice for modifications to increase mechanical strength, adding wool fiber does not improve mechanical properties but also does not worsen them much. Wool fibers are a good filler that accelerates degradation and are also a waste, which reduces the potential costs of producing such a biocomposite. The research established that these biocomposites maintain sufficient mechanical properties for packaging applications while offering better environmental resistance than pure polylactide, contributing to the development of circular economy solutions for agricultural waste valorization. So far, no studies have been conducted in the literature on the influence of sheep wool and its modified versions on the mechanical properties and the influence of modification on the degradation rate of PLA\/sheep wool biocomposites.<\/jats:p>","DOI":"10.3390\/ma18133056","type":"journal-article","created":{"date-parts":[[2025,6,30]],"date-time":"2025-06-30T11:37:51Z","timestamp":1751283471000},"page":"3056","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["The Influence of Various Chemical Modifications of Sheep Wool Fibers on the Long-Term Mechanical Properties of Sheep Wool\/PLA Biocomposites"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0861-6195","authenticated-orcid":false,"given":"Piotr","family":"Szatkowski","sequence":"first","affiliation":[{"name":"Department of Glass Technology and Amorphous Coatings, Faculty of Materials Science and Ceramics, AGH University of Krakow, Al. Mickiewicza 30, 30-059 Krakow, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,6,27]]},"reference":[{"key":"ref_1","first-page":"50","article-title":"Badanie impedancji, ciep\u0142ochronno\u015bci i napr\u0119\u017cenia zrywaj\u0105cego we\u0142ny jednolitej i mieszanej","volume":"56","author":"Michalak","year":"2018","journal-title":"Wiad. Zootech."},{"key":"ref_2","first-page":"35","article-title":"Wykorzystanie pozaklasowego w\u0142\u00f3kna alpak i we\u0142ny owczej do zastosowania w r\u00f3\u017cnych sektorach gospodarki","volume":"6","author":"Villavicencio","year":"2022","journal-title":"Prz. W\u0142\u00f3k.-W\u0142\u00f3kno Odzie\u017c Sk\u00f3ra"},{"key":"ref_3","first-page":"1","article-title":"The potential application of sheep wool as a component of composites","volume":"17","author":"Szatkowski","year":"2021","journal-title":"Rocz. Nauk. Pol. Towar. Zootech."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Simpson, W.S., and Crawshaw, G.H. (2002). Wool: Science and Technology, CRC Press LLC.","DOI":"10.1201\/9781439823460"},{"key":"ref_5","unstructured":"Ni\u017cnikowski, R. (2011). Hodowla i U\u017cytkowanie Owiec, Wydawnictwo Wie\u015b Jutra."},{"key":"ref_6","first-page":"50","article-title":"Materia\u0142y naturalne w ekobudownictwie","volume":"88","author":"Wasilewska","year":"2017","journal-title":"Przegl\u0105d Bud."},{"key":"ref_7","first-page":"5","article-title":"Polimery biodegradowalne do zastosowa\u0144 biomedycznych","volume":"6","author":"Andrzejewska","year":"2015","journal-title":"Post\u0119p. In\u017c. Mech."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1016\/j.polymdegradstab.2015.05.015","article-title":"Effects of wool fibres, ammonium polyphosphate and polymer viscosity on the flammability and mechanical performance of PP\/wool composites","volume":"119","author":"Kim","year":"2015","journal-title":"Polym. Degrad. Stab."},{"key":"ref_9","first-page":"194","article-title":"A review on natural fibers","volume":"8","author":"Chandramohan","year":"2011","journal-title":"Int. J. Res. Rev. Appl. Sci."},{"key":"ref_10","first-page":"270","article-title":"Kompozyty polimerowe z ro\u015blinnymi w\u0142\u00f3knami naturalnymi na potrzeby wsp\u00f3\u0142czesnej motoryzacji","volume":"83","author":"Pach","year":"2010","journal-title":"Mechanik"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"21","DOI":"10.5604\/12303666.1215522","article-title":"Comparison of Selected Chemical Properties of Fibres from Different Breeds of Dogs and German Blackface Sheep","volume":"24","author":"Ivanauskas","year":"2016","journal-title":"Fibres Text. East. Eur."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"105619","DOI":"10.1016\/j.compositesa.2019.105619","article-title":"Glass fibre sizing: A review","volume":"127","author":"Thomason","year":"2019","journal-title":"Compos. Part Appl. Sci. Manuf."},{"key":"ref_13","first-page":"45","article-title":"Kompozyty polimerowe zawieraj\u0105ce w\u0142\u00f3kna ro\u015blinne\u2014Czynniki wp\u0142ywaj\u0105ce na wytrzyma\u0142o\u015b\u0107 mechaniczn\u0105","volume":"63","author":"Miedzianowska","year":"2018","journal-title":"Technol. Jako\u015b\u0107 Wyr."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"367","DOI":"10.1016\/S0266-3538(02)00217-8","article-title":"Manufacturing sisal\u2013polypropylene composites with minimum fibre degradation","volume":"63","author":"Jayaraman","year":"2003","journal-title":"Compos. Sci. Technol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1002\/pc.20461","article-title":"Recent developments in chemical modification and characterization of natural fiber-reinforced composites","volume":"29","author":"John","year":"2008","journal-title":"Polym. Compos."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1880","DOI":"10.1016\/j.mspro.2014.07.507","article-title":"Flammability Characteristics of Chemical Treated Woven Natural Fabric Reinforced Phenol Formaldehyde Composites","volume":"5","author":"Bharath","year":"2014","journal-title":"Procedia Mater. Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"138","DOI":"10.1257\/aer.98.2.138","article-title":"Should the Euro Area Be Run as a Closed Economy","volume":"98","author":"Favero","year":"2008","journal-title":"Am. Econ. Rev."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"562","DOI":"10.1016\/j.conbuildmat.2016.10.096","article-title":"The use of wool as fiber-reinforcement in cement-based mortar","volume":"139","author":"Fantilli","year":"2017","journal-title":"Constr. Build. Mater."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"124013","DOI":"10.1016\/j.jclepro.2020.124013","article-title":"The financial impact of replacing plastic packaging by biodegradable biopolymers\u2014A smart solution for the food industry","volume":"277","author":"Stoica","year":"2020","journal-title":"J. Clean. Prod."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Patrucco, A., Zoccola, M., and Anceschi, A. (2024). Exploring the Potential Applications of Wool Fibers in Composite Materials: A Review. Polymers, 16.","DOI":"10.3390\/polym16162360"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"57","DOI":"10.5604\/01.3001.0016.0365","article-title":"Production of biodegradable packaging with sheep wool fibres for medical applications","volume":"18","author":"Szatkowski","year":"2022","journal-title":"Anim. Sci. Genet."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Jose, S., George, J.S., Jacob, T.A., Vijayan, P.P., Bhanu, A.V.A., Nedumpillil, N.N., and Thomas, S. (2023). Nanosilica incorporated coarse wool-epoxy hybrid biocomposites with improved physico-mechanical properties. Front. Mater., 10.","DOI":"10.3389\/fmats.2023.1140602"},{"key":"ref_23","first-page":"1186","article-title":"Biodegradable composite from discarded hair keratin and graphene oxide with improved mechanical, thermal and barrier properties: An eco-friendly solution to waste materials","volume":"72","author":"Rahaman","year":"2023","journal-title":"Polym. Int."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Raghvendra, G., Ojha, S., Acharya, S.K., and Pal, S.K. (2023). Green Composites Based on Animal Fiber and Their Applications for a Sustainable Future. Polymers, 15.","DOI":"10.3390\/polym15030601"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Adamczyk, K., Siwek, P., and Micha\u0142ek, B. (2025). Exploring Advancements in Bio-Based Composites for Thermal Insulation: A Systematic Review. Sustainability, 17.","DOI":"10.3390\/su17031143"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"549","DOI":"10.3390\/textiles4040032","article-title":"A Novel Biodegradable Technology for Wool Fabric Restoration and Cotton Color Retention Based on Shikimic Acid and L-Arginine","volume":"4","author":"Kowalczyk","year":"2024","journal-title":"Textiles"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Kumar, A., Singh, P., and Sharma, R. (2024). Investigation of Damping Properties of Natural Fiber-Reinforced Composites at Various Impact Energy Levels. Polymers, 16.","DOI":"10.3390\/polym16243553"},{"key":"ref_28","unstructured":"Berechet, M.D., Niculescu, O., Deselnicu, D.C., and Georgescu, M. (2024, January 16\u201318). Short Review on Keratin Synthesis and Its Applications in Composite Materials. Proceedings of the ICAMS 2024 Conference, Bucharest, Romania."},{"key":"ref_29","unstructured":"(2020). Plastics\u2014Determination of Tensile Properties\u2014Part 1: General Principles (Standard No. EN ISO 527-1:2020)."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Golubovi\u0107, Z., Bojovi\u0107, B., Kirin, S., Milovanovi\u0107, A., Petrov, L., An\u0111elkovi\u0107, B., and Sofreni\u0107, I. (2024). Effect of Aging on Tensile and Chemical Properties of Polylactic Acid and Polylactic Acid-Like Polymer Materials for Additive Manufacturing. Polymers, 16.","DOI":"10.3390\/polym16081035"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1021\/acsmaterialsau.3c00065","article-title":"UV Light Degradation of Polylactic Acid Kickstarts Enzymatic Hydrolysis","volume":"4","author":"Brown","year":"2024","journal-title":"ACS Mater. Au"},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Mihai, M., Rapa, M., Darie-Nita, R.N., and Vasile, C. (2020). Dynamic Mechanical Analysis Investigations of PLA-Based Renewable Materials: How Are They Useful?. Materials, 13.","DOI":"10.3390\/ma13225302"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Shi, Z., Zou, C., Zhou, F., and Zhao, J. (2022). Analysis of the Mechanical Properties and Damage Mechanism of Carbon Fiber\/Epoxy Composites under UV Aging. Materials, 15.","DOI":"10.3390\/ma15082919"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Ghasemian, R., Barani, H., and Khazaei, F. (2025). Surface modification and performance of wool fibers after combined plasma and enzyme treatments. Sci. Rep., 15.","DOI":"10.1038\/s41598-025-93665-3"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"634","DOI":"10.1016\/j.tifs.2008.07.003","article-title":"Biodegradable polymers for food packaging: A review","volume":"19","author":"Siracusa","year":"2008","journal-title":"Trends Food Sci. Technol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"134","DOI":"10.1016\/j.mattod.2022.01.022","article-title":"Recent advances in polymers and polymer composites for food packaging","volume":"53","author":"Zhang","year":"2022","journal-title":"Mater. Today."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"4484","DOI":"10.1016\/j.matpr.2021.05.322","article-title":"Assessing the potentials of Bamboo and sheep wool fiber as sustainable construction materials: A review","volume":"47","author":"Tiza","year":"2021","journal-title":"Mater. Today Proc."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1016\/j.addr.2016.04.003","article-title":"PLA composites: From production to properties","volume":"107","author":"Murariu","year":"2016","journal-title":"Adv. Drug Deliv. Rev."},{"key":"ref_39","first-page":"703","article-title":"Life cycle energy consumption and greenhouse gas emissions of polylactic acid (PLA) and polystyrene (PS) trays","volume":"44","author":"Suwanmanee","year":"2010","journal-title":"Agric. Nat. Resour."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"101216","DOI":"10.1016\/j.jobe.2020.101216","article-title":"Utilization of sheep wool as potential fibrous materials in the production of concrete composites","volume":"30","author":"Alyousef","year":"2020","journal-title":"J. Build. Eng."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"J\u00f3\u017awiak-Nied\u017awiedzka, D., and Fantilli, A.P. (2020). Wool-Reinforced Cement Based Composites. Materials, 13.","DOI":"10.3390\/ma13163590"},{"key":"ref_42","unstructured":"Statuto, D., Bochicchio, M., Sica, C., and Picuno, P. (March, January 27). Experimental development of clay bricks reinforced with agricultural by-products. Proceedings of the ATAE2018 Symposium, Opatija, Croatia."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1532","DOI":"10.1080\/15440478.2019.1584075","article-title":"Effect of Sheep Wool Fibers on Thermal Insulation and Mechanical Properties of Cement-Based Composites","volume":"17","author":"Fiore","year":"2020","journal-title":"J. Nat. Fibers"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1","DOI":"10.5958\/0973-9718.2019.00019.9","article-title":"Potential use of waste wool in agriculture: An overview","volume":"25","author":"Sharma","year":"2019","journal-title":"Indian J. Small Rumin."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1016\/j.compscitech.2004.06.011","article-title":"Polyethylene reinforced with keratin fibers obtained from chicken feathers","volume":"65","author":"Barone","year":"2005","journal-title":"Compos. Sci. Technol."},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Ferreira, D., Cruz, J., and Fangueiro, R. (2018). Surface modification of natural fibers in polymer composites. Green Composites for Automotive Applications, Woodhead Publishing.","DOI":"10.1016\/B978-0-08-102177-4.00001-X"}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/18\/13\/3056\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:00:01Z","timestamp":1760032801000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/18\/13\/3056"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,6,27]]},"references-count":46,"journal-issue":{"issue":"13","published-online":{"date-parts":[[2025,7]]}},"alternative-id":["ma18133056"],"URL":"https:\/\/doi.org\/10.3390\/ma18133056","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,6,27]]}}}