{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,5]],"date-time":"2025-12-05T18:11:46Z","timestamp":1764958306140,"version":"3.46.0"},"reference-count":52,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2025,12,2]],"date-time":"2025-12-02T00:00:00Z","timestamp":1764633600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"PRR\u2014Plano de Recupera\u00e7\u00e3o e Resili\u00eancia","award":["C644919832-00000035"],"award-info":[{"award-number":["C644919832-00000035"]}]},{"name":"FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia, I.P.","award":["UID 00481\/2025"],"award-info":[{"award-number":["UID 00481\/2025"]}]},{"name":"CICECO\u2014Aveiro Institute of Materials","award":["UIDB\/50011\/2020","UIDP\/50011\/2020","LA\/P\/0006\/2020"],"award-info":[{"award-number":["UIDB\/50011\/2020","UIDP\/50011\/2020","LA\/P\/0006\/2020"]}]},{"name":"FCT\/MCTES","award":["UIDB\/50006\/2020","UIDP\/50006\/2020"],"award-info":[{"award-number":["UIDB\/50006\/2020","UIDP\/50006\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Compos. Sci."],"abstract":"<jats:p>The growing demand for sustainable materials in construction and sanitation has increased interest in natural fibre-reinforced polymer composites. Rice husk, an abundant agricultural by-product, offers a promising alternative as a reinforcing filler in polypropylene (PP) composites. This study aims to assess the suitability of PP composites reinforced with micronised rice husk particles for application in sanitary components. Two formulations containing 20% and 30% rice husk were developed and characterised. Comprehensive analysis included morphological, thermal, rheological, mechanical, hygroscopic, and tribological testing. Results showed that particles incorporation enhanced thermal stability and crystallinity due to a nucleating effect, with the 30% composite showing higher crystallinity. Thermogravimetric analysis showed that although the T5% decreased from 374.1 \u00b0C for neat PP to 309.2 \u00b0C and 296.2 \u00b0C for the 20% and 30% composites, respectively, the DTG peak temperatures increased by 15.9 \u00b0C and 17.6 \u00b0C, indicating a delayed main decomposition stage of PP matrix and enhanced overall thermal stability. Rheological behaviour revealed increased viscosity and pseudoplasticity at higher particle content Mechanical characterisation showed an increase in Young\u2019s modulus from 1021 MPa for neat PP to 1065 MPa (+4%) and 1125 MPa (+10%) for PP_Rice_20% and PP_Rice_30%, respectively. In contrast, the nominal strain at break dropped sharply from 238% (PP) to 30% (PP_Rice_20%) and 16% (PP_Rice_30%). Shrinkage decreased from 1.31% (PP) to approximately 1.05% in both composites, indicating improved dimensional stability. However, water absorption rose from 0.015% (PP) to 0.111% (PP_Rice_20%) and 0.144% (PP_Rice_30%), accompanied by an increase in surface roughness (Sa from 0.34 \u00b5m to 0.78 \u00b5m and 1.06 \u00b5m, respectively). The composite with 20% rice husk demonstrated better filler dispersion, reduced water uptake, and smoother surfaces, making it more suitable for injection-moulded components intended for use in humid environments. Overall, the study supports the use of agricultural residues in high-performance biocomposites, contributing to circular economy strategies and the development of more sustainable polymer-based materials for technical applications.<\/jats:p>","DOI":"10.3390\/jcs9120662","type":"journal-article","created":{"date-parts":[[2025,12,5]],"date-time":"2025-12-05T17:35:17Z","timestamp":1764956117000},"page":"662","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Rheological and Thermo-Mechanical Characterisation of Sustainable Polypropylene Composites Reinforced with Micronised Rice Husk"],"prefix":"10.3390","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-4718-8578","authenticated-orcid":false,"given":"In\u00eas","family":"Santos","sequence":"first","affiliation":[{"name":"TEMA\u2014Centre for Mechanical Technology and Automation, Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2150-6241","authenticated-orcid":false,"given":"Tatiana","family":"Zhiltsova","sequence":"additional","affiliation":[{"name":"TEMA\u2014Centre for Mechanical Technology and Automation, Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro, Portugal"},{"name":"LASI\u2014Intelligent Systems Associate Laboratory, 4800-058 Guimar\u00e3es, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1564-5728","authenticated-orcid":false,"given":"Jos\u00e9 Martinho","family":"Oliveira","sequence":"additional","affiliation":[{"name":"EMaRT Group\u2014Emerging: Materials, Research, Technology, University of Aveiro, Estrada do Cercal, 449, Santiago de Riba-Ul, 3720-511 Oliveira de Azem\u00e9is, Portugal"},{"name":"School of Design, Management and Production Technologies Northern Aveiro (ESAN), University of Aveiro, Estrada do Cercal, 449, Santiago de Riba-Ul, 3720-511 Oliveira de Azem\u00e9is, Portugal"},{"name":"Aveiro Institute of Materials (CICECO), University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9930-9486","authenticated-orcid":false,"given":"Sara P. Magalh\u00e3es","family":"da Silva","sequence":"additional","affiliation":[{"name":"EMaRT Group\u2014Emerging: Materials, Research, Technology, University of Aveiro, Estrada do Cercal, 449, Santiago de Riba-Ul, 3720-511 Oliveira de Azem\u00e9is, Portugal"},{"name":"School of Design, Management and Production Technologies Northern Aveiro (ESAN), University of Aveiro, Estrada do Cercal, 449, Santiago de Riba-Ul, 3720-511 Oliveira de Azem\u00e9is, Portugal"},{"name":"Aveiro Institute of Materials (CICECO), University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6190-1238","authenticated-orcid":false,"given":"M\u00f3nica S. A.","family":"Oliveira","sequence":"additional","affiliation":[{"name":"TEMA\u2014Centre for Mechanical Technology and Automation, Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro, Portugal"},{"name":"LASI\u2014Intelligent Systems Associate Laboratory, 4800-058 Guimar\u00e3es, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Ngo, T.-D. (2020). Introduction to Composite Materials. Composite and Nanocomposite Materials\u2014From Knowledge to Industrial Applications, IntechOpen.","DOI":"10.5772\/intechopen.91285"},{"key":"ref_2","unstructured":"(2025, April 23). Polipropileno\u2014Pre\u00e7os|2013\u20132025 Dados|2026\u20132027 Previs\u00e3o. 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