Production of a novel bio-based structural adhesive and characterization of mechanical properties

ABSTRACT

Herein, a novel bio-based structural adhesive is produced, and its mechanical properties are characterized. The bio-based adhesive is a mixture of three parts: the bio-based epoxy resin, the environmentally friendly hardener and a reactive diluent. The bio-based epoxy resin is produced from epichlorohydrin, which is based on glycerin, while the environmentally friendly hardener and the epoxy diluent are based on cardanol. The epoxy resin and the diluent are mixed in vacuum and afterwards the hardener is added into the mixture, also in vacuum. All products are in a proper stoichiometric ratio. Once mixed thoroughly and degassed completely the adhesive is ready to be applied on the molds to produce specimens for tests. The samples were cured at 80°C for 6 h and post-cured at 140°C for 8 h. The thermomechanical behavior of the bio-adhesive was characterized by dynamical mechanical analysis and the mechanical behavior by means of tension tests and fracture toughness tests on bulk specimens and single-lap shear tests on composite bonded joints. The results from the tests reveal a high processing quality and mechanical performance of the epichlorohydrin/cardanol bio-based adhesive compared to commercial oil-based structural adhesives, which makes the bio-adhesive a strong candidate for use in structural applications.

KEYWORDS:

• Novel adhesives
• Bioadhesion
• Aeronautical
• Dynamic mechanical analysis
• Destructive testing

Acknowledgements

The authors would like to thank the personnel of the Smart Materials and Nanodielectrics Laboratory, Prof. G.C Psarras and post-doctoral researcher A.C. Patsidis, for their support to the dynamic mechanical analysis experiment.