{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T00:22:47Z","timestamp":1791850967915,"version":"4.3.4"},"reference-count":36,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2025,2,18]],"date-time":"2025-02-18T00:00:00Z","timestamp":1739836800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Plano de Recupera\u00e7\u00e3o e Resili\u00eancia (PRR)","award":["03\/C05-i02\/2022"],"award-info":[{"award-number":["03\/C05-i02\/2022"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>This study aims to investigate the behaviour of thermoplastic composites reinforced with natural fibres. Composite materials were developed using reactive methyl methacrylate (MMA) resin, commercially known as Elium\u00ae (Arkema, Colombes, France), with the incorporation of cellulose nanocrystals (CNCs), dispersed in the matrix at different concentrations. Natural fibres, such as flax, were chemically treated by immersion in an aqueous solution based on NaHCO3, during different periods of exposure. After this treatment, flax fibres were washed with distilled water and dried. The degree of fibre surface tension was measured in terms of the contact angle. Then, cellulose nanocrystals were incorporated and mixed in the thermoplastic resin, and the samples were developed via the incorporation of intercalated layers of treated flax fibres. The composites were produced using compression moulding. After that, the samples were evaluated, regarding their mechanical performance and morphology. The research results show that flax fibres treated with 9 wt. % NaHCO3 for 48 h had improved flexural strength as a result of removing impurities and exposing hydroxyl groups that react with Na+ ions present in NaHCO3, which enhances its mechanical properties. The incorporation of 1% CNCs into thermoplastic resin significantly enhanced the fibre\/matrix interface, resulting in a remarkable 38% increase in flexural strength. These findings demonstrate the effectiveness of using treated natural fibres and CNCs to improve composites\u2019 performance.<\/jats:p>","DOI":"10.3390\/polym17040532","type":"journal-article","created":{"date-parts":[[2025,2,18]],"date-time":"2025-02-18T12:16:37Z","timestamp":1739880997000},"page":"532","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Mechanical Performance Enhancement in Natural Fibre-Reinforced Thermoplastic Composites Through Surface Treatment and Matrix Functionalisation"],"prefix":"10.3390","volume":"17","author":[{"given":"\u00c2ngela","family":"Pinto","sequence":"first","affiliation":[{"name":"Fibrenamics, Institute of Innovation on Fibre-Based Materials and Composites, University of Minho, 4800-058 Guimar\u00e3es, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dina","family":"Esteves","sequence":"additional","affiliation":[{"name":"Fibrenamics, Institute of Innovation on Fibre-Based Materials and Composites, University of Minho, 4800-058 Guimar\u00e3es, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1442-5128","authenticated-orcid":false,"given":"Lu\u00eds","family":"Nobre","sequence":"additional","affiliation":[{"name":"Fibrenamics, Institute of Innovation on Fibre-Based Materials and Composites, University of Minho, 4800-058 Guimar\u00e3es, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0950-4961","authenticated-orcid":false,"given":"Jo\u00e3o","family":"Bessa","sequence":"additional","affiliation":[{"name":"Fibrenamics, Institute of Innovation on Fibre-Based Materials and Composites, University of Minho, 4800-058 Guimar\u00e3es, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fernando","family":"Cunha","sequence":"additional","affiliation":[{"name":"Fibrenamics, Institute of Innovation on Fibre-Based Materials and Composites, University of Minho, 4800-058 Guimar\u00e3es, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ra\u00fal","family":"Fangueiro","sequence":"additional","affiliation":[{"name":"Fibrenamics, Institute of Innovation on Fibre-Based Materials and Composites, University of Minho, 4800-058 Guimar\u00e3es, Portugal"},{"name":"Department of Textile Engineering, University of Minho, Azur\u00e9m Campus, 4800-058 Guimar\u00e3es, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,2,18]]},"reference":[{"key":"ref_1","unstructured":"Seydibeyo\u011flu, M.\u00d6., Mohanty, A.K., and Misra, M. (2017). Fiber Reinforced Composites. Fiber Technology for Fiber-Reinforced Composites, Woodhead Publishing."},{"key":"ref_2","first-page":"2","article-title":"Fiber Reinforced Composites\u2014A Review","volume":"6","author":"Prashanth","year":"2017","journal-title":"J. Mater. Sci. Eng."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1616","DOI":"10.1016\/j.matpr.2020.04.851","article-title":"A Review on Natural Fiber Reinforced Composites","volume":"28","author":"Kerni","year":"2020","journal-title":"Mater. Today Proc."},{"key":"ref_4","first-page":"547","article-title":"Polymer Matrix Composite with Natural and Synthetic Fibres","volume":"6","author":"Begum","year":"2020","journal-title":"Adv. Mater. Process. Technol."},{"key":"ref_5","first-page":"198","article-title":"A Review on the Properties of Natural Fibres and its Bio-Composites: Effect of Alkali Treatment","volume":"234","author":"Sahu","year":"2019","journal-title":"Proc. Inst. Mech. Eng. Part L J. Mater. Des. Appl."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"82","DOI":"10.2478\/ftee-2022-0011","article-title":"Surface Treatments of Natural Fibres in Fibre Reinforced Composites: A Review","volume":"30","author":"Seisa","year":"2022","journal-title":"Fibres Text. East. Eur."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"569","DOI":"10.1007\/BF01151234","article-title":"Fibre-Matrix Adhesion and Its Relationship to Composite Mechanical Properties","volume":"28","author":"Drzal","year":"1993","journal-title":"J. Mater. Sci."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2153","DOI":"10.1177\/1528083716654468","article-title":"Hydrophobic Treatment of Natural Fibers and Their Composites\u2014A Review","volume":"47","author":"Ali","year":"2016","journal-title":"J. Ind. Text."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Rana, S., and Fangueiro, R. (2016). Natural Fibers for Composite Applications. Fibrous and Textile Materials for Composite Applications, Springer. Textile Science and Clothing Technology.","DOI":"10.1007\/978-981-10-0234-2"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Arunachalam, S.J., Saravanan, R., and Anbuchezhiyan, G. (2024). An Overview on Chemical Treatment in Natural Fiber Composites. Mater. Today Proc., in press.","DOI":"10.1016\/j.matpr.2024.05.108"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Samanth, M., and Subrahmanya Bhat, K. (2023). Conventional and Unconventional Chemical Treatment Methods of Natural Fibres for Sustainable Biocomposites. Sustain. Chem. Clim. Action, 3.","DOI":"10.1016\/j.scca.2023.100034"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1753","DOI":"10.1007\/s00170-019-04628-8","article-title":"Effect of Eco-Friendly Chemical Sodium Bicarbonate Treatment on the Mechanical Properties of Flax Fibres: Weibull Statistics","volume":"106","author":"Belaadi","year":"2020","journal-title":"Int. J. Adv. Manuf. Technol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"6711","DOI":"10.1002\/pc.26779","article-title":"Environmentally Sustainable Chemical Treatment of Plant Fibers for Improved Performance of Polymeric Composites","volume":"43","author":"Das","year":"2022","journal-title":"Polym. Compos."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Santos, J.C., Oliveira, P.R., Freire, R.T.S., Vieira, L.M.G., Rubio, J.C.C., and Panzera, T.H. (2022). The Effects of Sodium Carbonate and Bicarbonate Treatments on Sisal Fibre Composites. Mater. Res., 25.","DOI":"10.1590\/1980-5373-mr-2021-0464"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Sanfilippo, C., Fiore, V., Calabrese, L., Megna, B., and Valenza, A. (2024). Effect of Sodium Bicarbonate Treatment on the Properties of Sisal Fibers and Their Geopolymer Composites. Case Stud. Constr. Mater., 21.","DOI":"10.1016\/j.cscm.2024.e03536"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Stanley, W.F., Bandaru, A.K., Rana, S., Parveen, S., and Pichandi, S. (2021). Mechanical, Dynamic-Mechanical and Wear Performance of Novel Non-Crimp Glass Fabric-Reinforced Liquid Thermoplastic Composites Filled with Cellulose Microcrystals. Mater. Des., 212.","DOI":"10.1016\/j.matdes.2021.110276"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1267","DOI":"10.1002\/pc.29035","article-title":"Effect of Fiber Surface Treatment with Silane Coupling Agents and Carbon Nanotubes on Mechanical Properties of Carbon Fiber Reinforced Polyamide 6 Composites","volume":"46","author":"Du","year":"2024","journal-title":"Polym. Compos."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"3601","DOI":"10.1177\/00219983231190694","article-title":"Influence of Fibre Orientation, Moisture Absorption and Repairing Performance on the Low-Velocity Impact Response of Woven Flax\/Elium\u00ae Thermoplastic Bio-Composites","volume":"57","author":"Manaii","year":"2023","journal-title":"J. Compos. Mater."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2872","DOI":"10.1007\/s10853-024-09349-2","article-title":"Effect of Microcrystalline Cellulose on the Mechanical Properties of Flax Reinforced Methylmethacrylate and Urethane Acrylate Composites","volume":"59","author":"Bandaru","year":"2024","journal-title":"J. Mater. Sci."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Calvino, C., Macke, N., Kato, R., and Rowan, S.J. (2020). Development, Processing and Applications of Bio-sourced Cellulose Nanocrystal Composites. Prog. Polym. Sci., 103.","DOI":"10.1016\/j.progpolymsci.2020.101221"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1757","DOI":"10.1016\/j.matpr.2020.07.360","article-title":"A Review on the Mechanical Properties of Bio Waste Particulate Reinforced Polymer Composites","volume":"37","author":"Jose","year":"2020","journal-title":"Mater. Today Proc."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Zinge, C., and Kandasubramanian, B. (2020). Nanocellulose Based Biodegradable Polymers. Eur. Polym. J., 133.","DOI":"10.1016\/j.eurpolymj.2020.109758"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Pratap, B., and Kumar Patel, V. Influence of NaHCO3 Treated Kenaf\/Nettle Fiber on Mechanical and Sliding Wear Performance of Epoxy Composites. Mater. Today Proc., 2024. in press.","DOI":"10.1016\/j.matpr.2024.06.003"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1531","DOI":"10.1080\/15440478.2020.1784817","article-title":"Comparative Evaluation of Chemical Treatment on the Physical and Mechanical Properties of Areca Frond, Banana, and Flax Fibers","volume":"19","author":"Heckadka","year":"2022","journal-title":"J. Nat. Fibers"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"29","DOI":"10.5109\/2321001","article-title":"Characterization of Sodium-Bicarbonate-Treated Zalacca Fibers as Composite Reinforcements","volume":"6","author":"Raharjo","year":"2019","journal-title":"Evergreen"},{"key":"ref_26","unstructured":"(2022). Standard Test Method for Determination of Airborne Particulate Matter in Ambient Air with the Use of a Low-Volume Sampler (Standard No. ASTM D7334-08 (R22))."},{"key":"ref_27","unstructured":"(2003). Plastics\u2014Determination of Flexural Properties (Standard No. BS EN ISO 178:2003)."},{"key":"ref_28","unstructured":"(2017). Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials (Standard No. ASTM D790-17)."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"150","DOI":"10.1016\/j.compositesb.2015.09.028","article-title":"A New Eco-Friendly Chemical Treatment of Natural Fibres: Effect of Sodium Bicarbonate on Properties of Sisal Fibre and Its Epoxy Composites","volume":"85","author":"Fiore","year":"2016","journal-title":"Compos. Part B Eng."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1253","DOI":"10.1002\/pen.21328","article-title":"Pretreatments of Natural Fibers and Their Application as Reinforcing Material in Polymer Composites\u2014A Review","volume":"49","author":"Kalia","year":"2009","journal-title":"Polym. Eng. Sci."},{"key":"ref_31","first-page":"012007","article-title":"The Influence of Alkaline Treatment on Thermal Stability of Flax Fibres","volume":"Volume 191","author":"Chaishome","year":"2017","journal-title":"Proceedings of the 2nd International Conference on Mining, Material and Metallurgical Engineering"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1","DOI":"10.9734\/JSRR\/2015\/12347","article-title":"Effect of Alkali, Esterification and Silane Surface Treatments on Properties of Flax Fibres","volume":"4","author":"Zhu","year":"2015","journal-title":"J. Sci. Res. Rep."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"269","DOI":"10.1179\/sic.2003.48.4.269","article-title":"Identification of Cellulosic Fibres by FTIR Spectroscopy: Thread and Single Fibre Analysis by Attenuated Total Reflectance","volume":"48","author":"Garside","year":"2003","journal-title":"Stud. Conserv."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"32","DOI":"10.4028\/www.scientific.net\/AMR.894.32","article-title":"Thermal Degradation of Flax Fibres as Potential Reinforcement in Thermoplastic Composites","volume":"894","author":"Chaishome","year":"2014","journal-title":"Adv. Mater. Res."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Volkov, D.S., Rogova, O.B., and Proskurnin, M.A. (2021). Organic Matter and Mineral Composition of Silicate Soils: FTIR Comparison Study by Photoacoustic, Diffuse Reflectance, and Attenuated Total Reflection Modalities. Agronomy, 11.","DOI":"10.3390\/agronomy11091879"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1016\/0040-6031(88)87099-0","article-title":"Thermogravimetric Analysis of Flax Fibres","volume":"132","author":"Sharma","year":"1988","journal-title":"Thermochim. Acta"}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/17\/4\/532\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T16:37:13Z","timestamp":1760027833000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/17\/4\/532"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,2,18]]},"references-count":36,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2025,2]]}},"alternative-id":["polym17040532"],"URL":"https:\/\/doi.org\/10.3390\/polym17040532","relation":{},"ISSN":["2073-4360"],"issn-type":[{"value":"2073-4360","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,2,18]]}}}