{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T14:27:54Z","timestamp":1785421674099,"version":"3.56.0"},"reference-count":52,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2026,5,13]],"date-time":"2026-05-13T00:00:00Z","timestamp":1778630400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002322","name":"Coordena\u00e7\u00e3o de Aperfei\u00e7oamento de Pessoal de N\u00edvel Superior","doi-asserted-by":"crossref","award":["001"],"award-info":[{"award-number":["001"]}],"id":[{"id":"10.13039\/501100002322","id-type":"DOI","asserted-by":"crossref"}]},{"award":["001"],"award-info":[{"award-number":["001"]}],"id":[{"id":"https:\/\/ror.org\/00x0ma614","id-type":"ROR","asserted-by":"publisher"}]},{"name":"FCT\/MECI","award":["UID\/00511\/2025"],"award-info":[{"award-number":["UID\/00511\/2025"]}]},{"name":"FCT\/MECI","award":["UID\/PRR\/00511\/2025"],"award-info":[{"award-number":["UID\/PRR\/00511\/2025"]}]},{"name":"FCT\/MECI","award":["LA\/P\/0045\/2020"],"award-info":[{"award-number":["LA\/P\/0045\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>The construction sector\u2019s drive for sustainability has increased the use of Cross-Laminated Timber (CLT), yet its structural reliability is governed by the integrity of the adhesive bond line. This study evaluates the influence of three one-component polyurethane (PUR) formulations (R1, R2, R3) on the adhesion performance of maritime pine CLT. To isolate adhesive-related effects, lamellas were mechanically classified by modulus of elasticity (MOE) and randomly allocated within stiffness classes. Adhesive characterization through ABES, FTIR, and DSC revealed that R3 exhibited slower cure kinetics (t0 = 5482 s) but higher thermal stability. Mechanical testing showed that all formulations developed structurally effective dry bonds with shear strengths exceeding 7.1 MPa, with R3 achieving significantly higher dry shear and interlaminar strength. However, 24 h water immersion caused a catastrophic strength reduction exceeding 95% across all formulations, shifting the failure mode from the wood substrate to the adhesive layer. DSC analysis identified glass transition temperatures between 28 \u00b0C and 32 \u00b0C, which are consistent with the potential for moisture-induced plasticization near service temperatures. These results indicate that while slower-curing formulations like R3 enhance bond quality in dense softwoods due to improved interphase formation, all evaluated PUR systems showed significant vulnerability to saturated conditions, suggesting that adequate moisture protection is essential for maritime pine CLT applications.<\/jats:p>","DOI":"10.3390\/ma19102030","type":"journal-article","created":{"date-parts":[[2026,5,13]],"date-time":"2026-05-13T12:46:55Z","timestamp":1778676415000},"page":"2030","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Influence of Polyurethane Adhesive Formulation on Shear Performance of Maritime Pine Cross-Laminated Timber Under Dry and Moist Exposure Conditions"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1838-1054","authenticated-orcid":false,"given":"Annie","family":"Cavalcante","sequence":"first","affiliation":[{"name":"Department of Forest Engineering, Faculty of Technology, University of Bras\u00edlia, Bras\u00edlia 70919-970, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1189-0497","authenticated-orcid":false,"given":"Jorge M.","family":"Martins","sequence":"additional","affiliation":[{"name":"Department of Wood Engineering, Polytechnic Institute of Viseu, 3504-510 Viseu, Portugal"},{"name":"Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"},{"name":"Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3745-9304","authenticated-orcid":false,"given":"Margarida Lopes de","family":"Almeida","sequence":"additional","affiliation":[{"name":"Department of Wood Engineering, Polytechnic Institute of Viseu, 3504-510 Viseu, Portugal"},{"name":"Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"},{"name":"Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3369-2392","authenticated-orcid":false,"given":"Cl\u00e1udio Henrique Soares","family":"Del Menezzi","sequence":"additional","affiliation":[{"name":"Department of Forest Engineering, Faculty of Technology, University of Bras\u00edlia, Bras\u00edlia 70919-970, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4557-7113","authenticated-orcid":false,"given":"Lu\u00edsa Hora de","family":"Carvalho","sequence":"additional","affiliation":[{"name":"Department of Wood Engineering, Polytechnic Institute of Viseu, 3504-510 Viseu, Portugal"},{"name":"Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"},{"name":"Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"107836","DOI":"10.1016\/j.buildenv.2021.107836","article-title":"Life Cycle Assessment and Life Cycle Costing of Multistorey Building: Attributional and Consequential Perspectives","volume":"197","author":"Fauzi","year":"2021","journal-title":"Build. Environ."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"104482","DOI":"10.1016\/j.jobe.2022.104482","article-title":"Cross-Laminated Timber for Building Construction: A Life-Cycle-Assessment Overview","volume":"52","author":"Younis","year":"2022","journal-title":"J. Build. Eng."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Mitterpach, J., Va\u0148ov\u00e1, R., \u0160edivka, P., and \u0160tefko, J. (2022). A Comparison of the Environmental Performance between Construction Materials and Operational Energy of Nearly Zero-Energy Wood-Based Educational Building. Forests, 13.","DOI":"10.3390\/f13020220"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"134941","DOI":"10.1016\/j.jclepro.2022.134941","article-title":"Substitution of Fossil-Energy Intensive Building Materials by Wood Products\u2014Does It Matter? A Case Study from Western Norway","volume":"383","author":"Simonsen","year":"2023","journal-title":"J. Clean. Prod."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Dukarska, D., and Mirski, R. (2023). Wood-Based Materials in Building. Materials, 16.","DOI":"10.3390\/ma16082987"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"333","DOI":"10.1016\/j.rser.2016.09.107","article-title":"The Wood from the Trees: The Use of Timber in Construction","volume":"68","author":"Ramage","year":"2017","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"192","DOI":"10.1016\/j.forpol.2017.08.007","article-title":"Review of Carbon Storage Function of Harvested Wood Products and the Potential of Wood Substitution in Greenhouse Gas Mitigation","volume":"85","author":"Geng","year":"2017","journal-title":"For. Policy Econ."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"17","DOI":"10.3992\/1943-4618.14.4.17","article-title":"Life cycle energy and environmental impacts of cross laminated timber made with coastal douglas-fir","volume":"14","author":"Puettmann","year":"2019","journal-title":"J. Green Build."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"139","DOI":"10.22382\/wfs-2018-047","article-title":"Method for Assessing the National Implications of Environmental Impacts from Timber Buildings-an Exemplary Study for Residential Buildings in Germany","volume":"50","author":"Hafner","year":"2018","journal-title":"Wood Fiber Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"403","DOI":"10.1111\/jiec.13139","article-title":"Whole-Life Embodied Carbon in Multistory Buildings: Steel, Concrete and Timber Structures","volume":"25","author":"Hart","year":"2021","journal-title":"J. Ind. Ecol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"217","DOI":"10.22382\/wfs-2020-019","article-title":"Comparative Life-Cycle Assessment of a Mass Timber Building and Concrete Alternative","volume":"52","author":"Liang","year":"2020","journal-title":"Wood Fiber Sci."},{"key":"ref_12","unstructured":"UNECE\/FAO (2021). Forest Products: Annual Market Review 2020-2021, United Nations and the Food and Agriculture Organization of the United Nations. 2020th\u20132021st ed."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"136991","DOI":"10.1016\/j.conbuildmat.2024.136991","article-title":"Out-of-Plane Bending Properties of Cross Laminated Timber (CLT)","volume":"438","author":"Brandner","year":"2024","journal-title":"Constr. Build. Mater."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Ren, H., Bahrami, A., Cehlin, M., and Wallhagen, M. (2024). Flexural Behavior of Cross-Laminated Timber Panels with Environmentally Timber Edge Connections. Buildings, 14.","DOI":"10.3390\/buildings14051455"},{"key":"ref_15","unstructured":"Brandner, R. (2013). Production and Technology of Cross Laminated Timber (CLT): A State-of-the-Art Report. Proceedings of the Focus Solid Timber Solutions\u2014European Conference on Cross Laminated Timber (CLT), University of Bath."},{"key":"ref_16","unstructured":"Karacabeyli, E., and Gagnon, S. (2019). CLT Handbook\u2014Canadian Edition, FPInnovations. [2nd ed.]."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"758","DOI":"10.1080\/00218464.2015.1094391","article-title":"Shear Strength and Durability Testing of Adhesive Bonds in Cross-Laminated Timber","volume":"92","author":"Sikora","year":"2016","journal-title":"J. Adhes."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Li, M., Zhang, S., Gong, Y., Tian, Z., and Ren, H. (2021). Gluing Techniques on Bond Performance and Mechanical Properties of Cross-Laminated Timber (Clt) Made from Larix Kaempferi. Polymers, 13.","DOI":"10.3390\/polym13050733"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"833","DOI":"10.1007\/s00107-017-1283-7","article-title":"The Evaluation of Panel Bond Quality and Durability of Hem-Fir Cross-Laminated Timber (CLT)","volume":"76","author":"Wang","year":"2018","journal-title":"Eur. J. Wood Wood Prod."},{"key":"ref_20","first-page":"e04026","article-title":"Evaluation of Shear Strength and Durability of Adhesive Bond in Cross-Laminated Timber (CLT) Panels Made from Nigerian Gmelina arborea Timber","volume":"21","author":"Yau","year":"2024","journal-title":"Case Stud. Constr. Mater."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1016\/j.ijadhadh.2013.01.015","article-title":"Influence of Moisture on Stress\u2013Strain Behaviour of Adhesives Used for Structural Bonding of Wood","volume":"44","author":"Trachsel","year":"2013","journal-title":"Int. J. Adhes. Adhes."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"104008","DOI":"10.1016\/j.ijadhadh.2025.104008","article-title":"Exploring Bonding and Interfacial Adhesion Properties of Normal and Reaction Wood in Wood-Based Composites\u2014A Review","volume":"140","author":"Purusatama","year":"2025","journal-title":"Int. J. Adhes. Adhes."},{"key":"ref_23","unstructured":"Pizzi, A., and Mittal, K.L. (2017). Polyurethane Adhesives. Handbook of Adhesive Technology, CRC Press. [3rd ed.]."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"130","DOI":"10.1016\/j.ijadhadh.2016.09.008","article-title":"Characterization of the Ageing Process of One-Component Polyurethane Moisture Curing Wood Adhesive","volume":"72","author":"Clerc","year":"2017","journal-title":"Int. J. Adhes. Adhes."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"502","DOI":"10.1080\/00218464.2024.2358076","article-title":"A Discussion on the Various Aspects of the Minimum Pressing Time for Polyurethane Adhesives","volume":"101","author":"Hogger","year":"2024","journal-title":"J. Adhes."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1541","DOI":"10.1080\/00218464.2025.2481107","article-title":"Adhesive Joint Formation between Porous Wood Adherends with One-Component Polyurethane Part 1","volume":"101","author":"Wick","year":"2025","journal-title":"J. Adhes."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Kamke, F.A., and Nairn, J.A. (2023). Advances in Structural Wood Products Adhesive Bonding. Advances in Structural Adhesive Bonding, Elsevier. [2nd ed.].","DOI":"10.1016\/B978-0-323-91214-3.00001-6"},{"key":"ref_28","first-page":"93","article-title":"A Brief Discussion on Advances in Polyurethane Applications","volume":"3","author":"Das","year":"2020","journal-title":"Adv. Ind. Eng. Polym. Res."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"5220","DOI":"10.1021\/ma500904d","article-title":"Polyether Urethane Hydrolytic Stability after Exposure to Deoxygenated Water","volume":"47","author":"Chaffin","year":"2014","journal-title":"Macromolecules"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"103358","DOI":"10.1016\/j.ijadhadh.2023.103358","article-title":"One-Component Polyurethane Adhesives in Timber Engineering Applications: A Review","volume":"123","author":"Shirmohammadli","year":"2023","journal-title":"Int. J. Adhes. Adhes."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2135","DOI":"10.15376\/biores.20.1.2135-2149","article-title":"Performance of Polyurethane Adhesive in Hardwood Cross-Laminated Timber","volume":"20","author":"Henfield","year":"2025","journal-title":"Bioresources"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"601","DOI":"10.1163\/156856108X379137","article-title":"Adhesive Groups and How They Relate to the Durability of Bonded Wood","volume":"23","author":"Frihart","year":"2009","journal-title":"J. Adhes. Sci. Technol."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Alegria, C., Roque, N., Albuquerque, T., Fernandez, P., and Ribeiro, M.M. (2021). Modelling Maritime Pine (Pinus pinaster Aiton) Spatial Distribution and Productivity in Portugal: Tools for Forest Management. Forests, 12.","DOI":"10.3390\/f12030368"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"571","DOI":"10.1016\/j.conbuildmat.2019.03.064","article-title":"Bonding Quality Assessment of Cross-Layered Maritime Pine Elements Glued with One-Component Polyurethane Adhesive","volume":"211","author":"Santos","year":"2019","journal-title":"Constr. Build. Mater."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1680\/jcoma.16.00043","article-title":"Grading of Maritime Pine from Sardinia (Italy) for Use in Cross-Laminated Timber","volume":"171","author":"Concu","year":"2018","journal-title":"Proc. Inst. Civ. Eng.-Constr. Mater."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"117741","DOI":"10.1016\/j.conbuildmat.2019.117741","article-title":"Reinforcement of Maritime Pine Cross-Laminated Timber Panels by Means of Natural Flax Fibers","volume":"233","author":"Valdes","year":"2020","journal-title":"Constr. Build. Mater."},{"key":"ref_37","unstructured":"(1973). Madeiras\u2013Determina\u00e7\u00e3o Retrac\u00e7\u00e3o da Madeira (Standard No. NP-615)."},{"key":"ref_38","unstructured":"(2019). Standard Test Method for Measuring the Effect of Temperature on the Cohesive Strength Development of Adhesives using Lap Shear Bonds under Tensile Loading (Standard No. ASTM D7998-19)."},{"key":"ref_39","unstructured":"(2008). Solid Wood Panels (SWP)\u2014Bonding Quality\u2014Test Method (Standard No. EN 13354:2008)."},{"key":"ref_40","unstructured":"(2010). Timber Structures\u2014Structural Timber and Glued Laminated Timber\u2014Determination of Some Physical and Mechanical Properties (Standard No. EN 408:2010)."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"331","DOI":"10.1007\/s10086-017-1631-6","article-title":"Evaluating Rolling Shear Strength Properties of Cross-Laminated Timber by Short-Span Bending Tests and Modified Planar Shear Tests","volume":"63","author":"Li","year":"2017","journal-title":"J. Wood Sci."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"557","DOI":"10.1002\/polb.20974","article-title":"The Influence of Hard-segments on Two-phase Structure and Shape Memory Properties of PCL-based Segmented Polyurethanes","volume":"45","author":"Ping","year":"2007","journal-title":"J. Polym. Sci. B Polym. Phys."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"7672","DOI":"10.1021\/acs.macromol.7b00871","article-title":"Clarifying the Origin of Multiple Melting of Segmented Thermoplastic Polyurethanes by Fast Scanning Calorimetry","volume":"50","author":"Balko","year":"2017","journal-title":"Macromolecules"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"80","DOI":"10.1080\/00218464.2013.784693","article-title":"Evaluation of Bonding Performance of Amino Polymers Using ABES","volume":"90","author":"Costa","year":"2014","journal-title":"J. Adhes."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"225","DOI":"10.1007\/s00107-015-0882-4","article-title":"Impact of Cold Temperatures on the Shear Strength of Norway Spruce Joints Glued with Different Adhesives","volume":"73","author":"Wang","year":"2015","journal-title":"Eur. J. Wood Wood Prod."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1007\/s00226-011-0410-6","article-title":"Adhesive Penetration in Beech Wood: Experiments","volume":"46","author":"Hass","year":"2012","journal-title":"Wood Sci. Technol."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"3909","DOI":"10.1016\/j.jmrt.2022.10.156","article-title":"Latest Advancements in High-Performance Bio-Based Wood Adhesives: A Critical Review","volume":"21","author":"Hussin","year":"2022","journal-title":"J. Mater. Res. Technol."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"2235","DOI":"10.1039\/D5GC05443E","article-title":"Modification Strategies for Bio-Based Polyurethanes in Flexible Electronic Devices: A Review","volume":"28","author":"Zhang","year":"2026","journal-title":"Green Chem."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1760","DOI":"10.1080\/00218464.2025.2495883","article-title":"Comparative Study into the Impact of Varying Curing and Test Conditions on the Strength and Failure Modes of Adhesives for Realistic Use Case Scenarios","volume":"101","author":"Thomas","year":"2025","journal-title":"J. Adhes."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"520","DOI":"10.1016\/j.conbuildmat.2019.06.143","article-title":"Bonding Performance of Portuguese Maritime Pine Glued Laminated Timber","volume":"223","author":"Martins","year":"2019","journal-title":"Constr. Build. Mater."},{"key":"ref_51","doi-asserted-by":"crossref","unstructured":"Glasner, D., Ringhofer, A., Brandner, R., and Schickhofer, G. (2023). Rolling Shear Strength of Cross Laminated Timber (CLT)\u2014Testing, Evaluation, and Design. Buildings, 13.","DOI":"10.3390\/buildings13112831"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"137479","DOI":"10.1016\/j.conbuildmat.2024.137479","article-title":"Rolling Shear Failure of CLT Transverse Layer: AE Characterization of Damage Mechanisms under Different Test Methods","volume":"440","author":"Wang","year":"2024","journal-title":"Constr. Build. Mater."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/10\/2030\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,26]],"date-time":"2026-05-26T08:26:53Z","timestamp":1779784013000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/10\/2030"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,5,13]]},"references-count":52,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2026,5]]}},"alternative-id":["ma19102030"],"URL":"https:\/\/doi.org\/10.3390\/ma19102030","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,5,13]]}}}