{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T05:02:24Z","timestamp":1787029344113,"version":"build-2736575974"},"reference-count":32,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2018,8,8]],"date-time":"2018-08-08T00:00:00Z","timestamp":1533686400000},"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>Epoxy resins are the most widely used systems for structural composite applications; however, they lack fracture toughness, impact strength and peel strength due to high cross-linking densities. Use of conventional toughening agents to combat this can lead to reductions in mechanical, thermal and processability properties desirable for bonded composite applications. In this work, an asymmetric triblock copolymer of poly(styrene)\u2013b\u2013poly(butadiene)\u2013b\u2013poly(methylmethacrylate) was used to modify an epoxy resin system, with the materials processed using both vacuum bag and positive pressure curing techniques. Interlaminar fracture toughness testing showed improvements in initiation fracture toughness of up to 88%, accompanied by a 6 \u00b0C increase in glass transition temperature and manageable reductions in gel-time. Shear testing resulted in a 121% increase in ultimate shear strain with only an 8% reduction in shear strength. Performance improvements were attributed to nano-structuring within the toughened resin system, giving rise to matrix cavitation and dissipation of crack front strain energy upon loading.<\/jats:p>","DOI":"10.3390\/polym10080888","type":"journal-article","created":{"date-parts":[[2018,8,9]],"date-time":"2018-08-09T03:33:48Z","timestamp":1533785628000},"page":"888","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["Triblock Copolymer Toughening of a Carbon Fibre-Reinforced Epoxy Composite for Bonded Repair"],"prefix":"10.3390","volume":"10","author":[{"given":"Andrew","family":"Charles","sequence":"first","affiliation":[{"name":"Aerospace Division, Defence Science and Technology Group, Fishermans Bend 3207, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8646-3150","authenticated-orcid":false,"given":"Andrew","family":"Rider","sequence":"additional","affiliation":[{"name":"Aerospace Division, Defence Science and Technology Group, Fishermans Bend 3207, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2018,8,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Baker, A., Dutton, S., and Kelly, D. (2004). Composite Materials for Aircraft Structures, American Institute of Aeronautics. [2nd ed.].","DOI":"10.2514\/4.861680"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1163\/156855506776382664","article-title":"Toughening of epoxy resins","volume":"9","author":"Unnikrishnan","year":"2006","journal-title":"Des. Monomers Polym."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"577","DOI":"10.1002\/pen.21282","article-title":"Development of epoxy\/hyperbranched blends for resin transfer molding and vacuum assisted resin transfer molding applications: Effect of a reactive diluent","volume":"49","author":"Cicala","year":"2009","journal-title":"Polym. Eng. Sci."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"716","DOI":"10.1002\/1097-4628(20001024)78:4<716::AID-APP40>3.0.CO;2-B","article-title":"Toughening of epoxy resin using acrylate-based liquid rubbers","volume":"78","author":"Ratna","year":"2000","journal-title":"J. Appl. Polym. Sci."},{"key":"ref_5","first-page":"73","article-title":"Thermoplastic Toughened Epoxy Networks and Their Toughening Mechanisms in Some Systems","volume":"13","author":"Rutnakornpituk","year":"2548","journal-title":"Naresuan Univ. J."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"5473","DOI":"10.1023\/A:1004427123388","article-title":"Toughening of epoxies through thermoplastic crack bridging","volume":"33","author":"Cardwell","year":"1998","journal-title":"J. Mater. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Kim, B.C., Park, S.W., and Lee, D.G. (2008). Fracture toughness of the nano-particle reinforced epoxy composite. Composite Structures, Elsevier.","DOI":"10.1016\/j.compstruct.2008.03.005"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"5516","DOI":"10.1007\/s10853-006-1025-4","article-title":"Strength and fracture toughness of nano and micron-silica particles bidispersed epoxy composites: Evaluated by fragility parameter","volume":"42","author":"Kwon","year":"2007","journal-title":"J. Mater. Sci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"6245","DOI":"10.1021\/ma0121868","article-title":"ABC Triblock Copolymers\/Epoxy\u2212Diamine Blends. 1. Keys to Achieve Nanostructured Thermosets","volume":"35","author":"Ritzenthaler","year":"2002","journal-title":"Macromolecules"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"530","DOI":"10.1016\/j.polymer.2006.11.038","article-title":"Toughening mechanisms of nanoparticle-modified epoxy polymers","volume":"48","author":"Johnsen","year":"2007","journal-title":"Polymer"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Pom\u00e1zi, \u00c1., and Toldy, A. (2017). Particle Distribution of Solid Flame Retardants in Infusion Moulded Composites. Polymers, 9.","DOI":"10.3390\/polym9070250"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1470","DOI":"10.1002\/polb.21166","article-title":"Epoxies toughened with triblock copolymers","volume":"45","author":"Hydro","year":"2007","journal-title":"J. Polym. Sci. Part B Polym. Phys."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"118","DOI":"10.1021\/ma0211075","article-title":"ABC Triblock Copolymers\/Epoxy\u2212Diamine Blends. 2. Parameters Controlling the Morphologies and Properties","volume":"36","author":"Ritzenthaler","year":"2003","journal-title":"Macromolecules"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2444","DOI":"10.1002\/polb.10595","article-title":"Mechanical properties of block copolymer vesicle and micelle modified epoxies","volume":"41","author":"Dean","year":"2003","journal-title":"J. Polym. Sci. Part B Polym. Phys."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1002\/masy.200350826","article-title":"A new class of epoxy thermosets","volume":"198","author":"Pascault","year":"2003","journal-title":"Macromol. Symp."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"971","DOI":"10.1016\/j.carbon.2015.07.076","article-title":"Hierarchical composites with high-volume fractions of carbon nanotubes: Influence of plasma surface treatment and thermoplastic nanophase-modified epoxy","volume":"94","author":"Rider","year":"2015","journal-title":"Carbon"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"6762","DOI":"10.1007\/s10853-013-7481-8","article-title":"The microstructure and fracture performance of styrene\u2013butadiene\u2013methylmethacrylate block copolymer-modified epoxy polymers","volume":"48","author":"Chong","year":"2013","journal-title":"J. Mater. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"398","DOI":"10.1016\/j.compositesa.2016.08.038","article-title":"Synergistic local toughening of high performance epoxy-matrix composites using blended block copolymer-thermoplastic thin films","volume":"91","author":"Bahrami","year":"2016","journal-title":"Compos. Part A Appl. Sci. Manuf."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"718","DOI":"10.1016\/j.compscitech.2007.09.005","article-title":"Understanding the effect of nano-modifier addition upon the properties of fibre reinforced laminates","volume":"68","author":"Quaresimin","year":"2008","journal-title":"Compos. Sci. Technol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"114","DOI":"10.1016\/j.polymer.2016.03.084","article-title":"Micron and nanostructured rubber toughened epoxy: A direct comparison of mechanical, thermomechanical and fracture properties","volume":"92","author":"Kamar","year":"2016","journal-title":"Polymer"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1016\/j.polymer.2017.01.009","article-title":"Nanoscale toughening of carbon fiber reinforced\/epoxy polymer composites (CFRPs) using a triblock copolymer","volume":"111","author":"Kamar","year":"2017","journal-title":"Polymer"},{"key":"ref_22","unstructured":"ASTM D5656-04 (2004). Standard Test Method for Thick-Adherend Metal Lap-Shear Joints for Determination of the Stress-Strain Behavior of Adhesives in Shear by Tension Loading, ASTM International."},{"key":"ref_23","unstructured":"ASTM D6272-02 (2002). Standard Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials by Four-Point Bending, ASTM International."},{"key":"ref_24","unstructured":"ASTM D5528-01 (2001). Standard Test Method for Mode I Interlaminar Fracture Toughness of Unidirectional Fiber-Reinforced Polymer Matrix Composites, ASTM International."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"269","DOI":"10.1520\/CTR10379J","article-title":"Round Robin Testing for Mode I Interlaminar Fracture Toughness of Composite Materials","volume":"15","author":"Martin","year":"1993","journal-title":"J. Compos. Technol. Res."},{"key":"ref_26","unstructured":"ASTM D3433-99 (2012). Standard Test Method for Fracture Strength in Cleavage of Adhesives in Bonded Metal Joints, ASTM International."},{"key":"ref_27","unstructured":"ASTM D3762-03 (2003). Standard Test Method for Adhesive-Bonded Surface Durability of Aluminum (Wedge Test), ASTM International."},{"key":"ref_28","unstructured":"BSS 7208 (1998). Crack Extension Force\u2014Adhesive Evaluation, Boeing Aircraft Company."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1080\/15583726908545897","article-title":"Cross-Linking\u2013Effect on Physical Properties of Polymers","volume":"3","author":"Nielsen","year":"1969","journal-title":"J. Macromol. Sci. Part C"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"2462","DOI":"10.1007\/BF01114293","article-title":"Toughening mechanisms in elastomer-modified epoxies","volume":"21","author":"Yee","year":"1986","journal-title":"J. Mater. Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1016\/j.engfracmech.2014.07.033","article-title":"Shear strength of adhesive layers\u2014Models and experiments","volume":"129","author":"Stigh","year":"2014","journal-title":"Eng. Fract. Mech."},{"key":"ref_32","unstructured":"ASTM D3171-15 (2015). Standard Test Methods for Constituent Content of Composite Materials, ASTM International."}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/10\/8\/888\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:17:30Z","timestamp":1760195850000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/10\/8\/888"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,8,8]]},"references-count":32,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2018,8]]}},"alternative-id":["polym10080888"],"URL":"https:\/\/doi.org\/10.3390\/polym10080888","relation":{},"ISSN":["2073-4360"],"issn-type":[{"value":"2073-4360","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,8,8]]}}}