A comparative study of accelerated weathering of epoxy resins based on DGEBA and HDGEBA
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The durability of epoxy resins is an important factor in applications of composites to timber engineering. We carried out a comparative study of the effect of accelerated weathering on epoxy resins based on the glycidyl ether of bisphenol A (DGEBA) or hydrogenated diglycidyl ether of bisphenol A (HDGEBA) cured with 2,2,4-trimethylene-1,6-hexadiamine, using various characterization tools, including mechanical and thermal testing and SEM to evaluate the effect of exposure to UV light, moisture and elevated temperature cycles on the properties of the resins. Mechanical testing showed that after 6 months accelerated weathering reduced by 50% the tensile strength of DGEBA-TMDA while HDGEBA-TMDA epoxies lost slightly less strength over the same exposure period. Elongation at break increased after 6 months of accelerated weathering from 5.1 ± 0.1% to 7.5 ± 0.3% for DGEBA-TMDA epoxy specimens, and from 0.9 ± 0.3% to 2.0 ± 0.1% for HDGEBA-TMDA epoxy specimens. FTIR of the epoxies showed increases in the absorbance of hydroxyl and carbonyl groups for both epoxies on accelerated weathering, but the hydroxyl and carbonyl indexes reached values 90 and 40% higher respectively for DGEBA than HDGEBA-based epoxy resins. While susceptibility to accelerated weathering on the molecular scale was clearly greater for the DGEBA-based epoxy on the molecular scale, this did not translate into a significant deterioration in mechanical properties relative to HDGEBA over the time scale of the accelerated weathering experiments.
KeywordsEpoxy resin FTIR Tensile testing Thermogravimetric analysis
The authors thank Mr. Andrew Wallace, Mr. Wayne Dillon and Mr. Tony Mackinnon for instrumental assistance, and Dr. Jason Watling from Bryan Holden Ltd. for donation of the UV Chamber. Mr. Awad’s studies are supported by the Higher Committee for Education Development (HCED) and The University of Anbar in Iraq.
- 1.Miesner M (2008) Photodegradation of adhesives used in wood composite materials: Ph.D. Thesis, University of British ColumbiaGoogle Scholar
- 14.Ren D (2010) Moisture-cure polyurethane wood adhesives: wood/adhesive interactions and weather durability: Ph.D. Thesis, Virginia Polytechnic Institute and State University, VirginiaGoogle Scholar
- 16.Seong LY (2004) Durability of fiber reinforced polymer composites under tropical: Ph.D. Thesis, Civil Engineering, National University of Singapore, SingaporeGoogle Scholar
- 20.Dahl S, Hannebäck A (2012) Effect of process variations on thermally curing polymeric materials within OEM surface treatment: M.Sc. Thesis, Chalmers University of Technology, Gothenburg, SwedenGoogle Scholar
- 22.Rabek JF (2012) Polymer photodegradation: mechanisms and experimental methods. Chapman and Hall, LondonGoogle Scholar
- 23.Okeson MA, Kellogg KG, Kallmeyer AR (2006) Impact damage growth in fiberglass/epoxy laminates subjected to moisture and low temperature thermal cycling. Proc. The Sixteenth International Offshore and Polar Engineering Conference: International Society of Offshore and Polar EngineersGoogle Scholar
- 28.Nagle DJ (2009) Infrared spectroscopic investigation of the effects of titania photocatalyst on the degradation of linear low density polyethylene film for commercial applications. Ph.D. Thesis, Queensland University of Technology, BrisbaneGoogle Scholar
- 29.Khalifa T (2011) The Effects of Elevated Temperatures on Fibre Reinforced Polymers for Strengthening Concrete Structures. Master Thesis, Queen's University, CanadaGoogle Scholar
- 30.Sikadur®-330 Product Data Sheet, Sikadur Australia Pty Limited (2015), Available http://aus.sika.com/en/solutions_products/document_library/product-datasheets/product-datasheets-sika-d.html?page=1 Accessed 23 March 2017
- 31.Hernandez DA, Orlandi MO (2016) Mechanical properties of composites materials SikaCarbodurs512, Sikadur 30 and Sikadur 330 Brasilian Congress of Engineering and Materials Science Natal, Brazil, 6–10 NovemberGoogle Scholar