{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T21:08:20Z","timestamp":1790629700029,"version":"4.1.0"},"reference-count":24,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2021,12,1]],"date-time":"2021-12-01T00:00:00Z","timestamp":1638316800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Recycling of materials attracts considerable attention around the world due to environmental and economic concerns. Recycled rubber is one of the most commonly used recyclable materials in a number of industries, including automotive and aeronautic because of their low weight and cost efficiency. In this research, devulcanized recycled rubber-based composites are designed with glass bubble microsphere, short glass fiber, aluminum chip and fine gamma alumina fiber (\u03b3-Al2O3) reinforcements. After the determination of the reinforcements with matrix, bending strength and fracture characteristics of the composite are investigated by three-point bending (3PB) tests. Halpin\u2013Tsai homogenization model is adapted to the rubber-based composites to estimate the moduli of the composites. Furthermore, the relevant toughening mechanisms for the most suitable reinforcements are analyzed and stress intensity factor, KIc and critical energy release rate, GIc in mode I are determined by 3PB test with single edge notch specimens. In addition, 3PB tests are simulated by finite element analysis and the results are compared with the experimental results. Microstructural and fracture surfaces analysis are carried out by means of scanning electron microscopy (SEM). Mechanical test results show that the reinforcement with glass bubbles, aluminum oxide ceramic fibers and aluminum chips generally increase the fracture toughness of the composites.<\/jats:p>","DOI":"10.3390\/polym13234215","type":"journal-article","created":{"date-parts":[[2021,12,2]],"date-time":"2021-12-02T02:40:02Z","timestamp":1638412802000},"page":"4215","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["Toughening Mechanism Analysis of Recycled Rubber-Based Composites Reinforced with Glass Bubbles, Glass Fibers and Alumina Fibers"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1222-9489","authenticated-orcid":false,"given":"Gamze Cakir","family":"Kabakci","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering, Atilim University, Ankara 06830, Turkey"},{"name":"ISAE-Supmeca-Paris, School of Mechanical and Manufacturing Engineering, 93400 Paris, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1042-0805","authenticated-orcid":false,"given":"Ozgur","family":"Aslan","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Atilim University, Ankara 06830, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Emin","family":"Bayraktar","sequence":"additional","affiliation":[{"name":"ISAE-Supmeca-Paris, School of Mechanical and Manufacturing Engineering, 93400 Paris, France"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,12,1]]},"reference":[{"key":"ref_1","unstructured":"(2021, September 17). 3M Glass Bubbles K Series, S Series and iM Series. Available online: http:\/\/multimedia.3m.com\/mws\/media\/91049O\/3m-glass-bubbles-k-s-and-im-series.pdf."},{"key":"ref_2","first-page":"411","article-title":"Alumina fibre fp","volume":"294","author":"Dhingra","year":"1980","journal-title":"Philos. Trans. R. Soc. London. Ser. A Math. Phys. Sci."},{"key":"ref_3","unstructured":"Williams, J.G. (1984). Fracture Mechanics of Polymers, Halsted Press."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1038\/nmat1849","article-title":"The Rise of Graphene","volume":"6","author":"Geim","year":"2007","journal-title":"Nat. Mater."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"408","DOI":"10.5254\/rct.12.87973","article-title":"Rubber recycling: Chemistry, processing, and applications","volume":"85","author":"Myhre","year":"2012","journal-title":"Rubber Chem. Technol."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Irez, A.B., Zambelis, G., and Bayraktar, E. (2019). A New Design of Recycled Ethylene Propylene Diene Monomer Rubber Modified Epoxy Based Composites Reinforced with Alumina Fiber: Fracture Behavior and Damage Analyses. Materials, 12.","DOI":"10.3390\/ma12172729"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.compositesb.2018.04.047","article-title":"Recycled and devulcanized rubber modified epoxy-based composites reinforced with nano-magnetic iron oxide","volume":"148","author":"Irez","year":"2018","journal-title":"Compos. Part B Eng."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Irez, A.B., Bayraktar, E., and Miskioglu, I. (2020). Fracture Toughness Analysis of Epoxy-Recycled Rubber-Based Composite Reinforced with Graphene Nanoplatelets for Structural Applications in Automotive and Aeronautics. Polymers, 12.","DOI":"10.3390\/polym12020448"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"714","DOI":"10.1016\/j.mee.2008.01.001","article-title":"Preparation of \u03b1 -alumina\/polymethacrylic acid composite abrasive and its cmp performance on glass substrate","volume":"85","author":"Zhang","year":"2008","journal-title":"Microelectron. Eng."},{"key":"ref_10","unstructured":"ASTM International (2019). Designation: D 790\u201403 Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials, ASTM International."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"3637","DOI":"10.1039\/c2jm15062j","article-title":"Reinforcement and interphase of polymer\/graphene oxide nano composites","volume":"22","author":"Wan","year":"2012","journal-title":"J. Mater. Chem."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Zhang, G., Wang, F., Dai, J., and Huang, Z. (2016). Effect of functionalization of graphene nanoplatelets on the mechanical and thermal properties of silicone rubber composites. Materials, 9.","DOI":"10.3390\/ma9020092"},{"key":"ref_13","first-page":"326","article-title":"Synergistic effect on the fracture toughness of hybrid short glass fiber and short carbon fiber reinforced polypropylene composites","volume":"A323","author":"Bernd","year":"2002","journal-title":"Mater. Sci. Eng."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"450","DOI":"10.1016\/j.matdes.2012.01.021","article-title":"Optimal design for the flexural behaviour of glass and carbon fibre reinforced polymer hybrid composites","volume":"37","author":"Chensong","year":"2012","journal-title":"Mater. Des."},{"key":"ref_15","unstructured":"Yalcin, B., Amos, S.E., Williams, M.J., Gunes, I.S., and Ista, T.K. (2021, July 03). 3M\u2122 Glass Bubbles iM16K for Reinforced Thermoplastics. Available online: www.3M.com\/glassbubbles."},{"key":"ref_16","first-page":"378","article-title":"Preparation of nano-scale \u03b1-Al2O3 powder by the sol-gel method","volume":"55","author":"Branch","year":"2011","journal-title":"Ceram.-Silik\u00e1ty"},{"key":"ref_17","first-page":"615624","article-title":"Tailoring size of \u03b1-Al2O3 nanopowders via polymeric gel-net method","volume":"19","author":"Amirshaghaghi","year":"2010","journal-title":"Iran. Polym. J"},{"key":"ref_18","first-page":"31","article-title":"Toughening Mechanism in Epoxy Resin Modified Recycled Rubber Based Composites Reinforced with Gamma-Alumina, Graphene and CNT","volume":"Volume 5","author":"Irez","year":"2019","journal-title":"Mechanics of Composite, Hybrid and Multifunctional Materials"},{"key":"ref_19","first-page":"73","article-title":"Design of a Low-Cost Aircraft Structural Material Based on Epoxy: Recycled Rubber Composites Modified with Multifunctional Nano","volume":"Volume 5","author":"Irez","year":"2019","journal-title":"Mechanics of Composite and Multi-Functional Materials"},{"key":"ref_20","first-page":"1","article-title":"Design and manufacturing of new elastomeric composites: Mechanical properties, chemical and 179 physical analysis","volume":"1","author":"Zaimova","year":"2016","journal-title":"Compos. Part B Eng."},{"key":"ref_21","first-page":"37","article-title":"Mechanical and Tribological Properties of Scrap Rubber Reinforced with Al2O3 Fiber, Aluminium and TiO2, Springer link","volume":"Volume 7","author":"Ferreira","year":"2017","journal-title":"Mechanics of Composite and Multi-Functional Materials"},{"key":"ref_22","unstructured":"Irez, A.B. (2018). Design, Development and Characterization of Recycled Rubber Modified Epoxy Based Composites: An Experimental Approach for Toughening Mechanisms. [Ph.D. Thesis, Universit\u00e9-Paris Saclay]."},{"key":"ref_23","first-page":"1","article-title":"A Review on the Mechanical Properties and Environmental Impact of Hollow Glass Microsphere Epoxy Composites","volume":"9","author":"Bhatia","year":"2018","journal-title":"IIOABJ"},{"key":"ref_24","first-page":"53","article-title":"Plastics Engineering, Fiber orientation and the creation of structural plastic lumber","volume":"55","author":"Nosker","year":"1999","journal-title":"Plast. Eng."}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/13\/23\/4215\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:38:26Z","timestamp":1760168306000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/13\/23\/4215"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,12,1]]},"references-count":24,"journal-issue":{"issue":"23","published-online":{"date-parts":[[2021,12]]}},"alternative-id":["polym13234215"],"URL":"https:\/\/doi.org\/10.3390\/polym13234215","relation":{},"ISSN":["2073-4360"],"issn-type":[{"value":"2073-4360","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,12,1]]}}}