Vol.:(0123456789) 1 3 Journal of Polymers and the Environment https://doi.org/10.1007/s10924-020-01904-7 ORIGINAL PAPER Performance of Sisal/Hemp Bio‑based Epoxy Composites Under Accelerated Weathering K. Senthilkumar 1  · Thitinun Ungtrakul 2  · M. Chandrasekar 3  · T. Senthil Muthu Kumar 4  · N. Rajini 4  · Suchart Siengchin 2  · Harikrishnan Pulikkalparambil 1  · Jyotishkumar Parameswaranpillai 2  · Nadir Ayrilmis 5 Accepted: 23 September 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract The biocomposites were produced by layering sequence of pure sisal fber mat (SSSS), pure hemp fber mat (HHHH), and their hybrid mats and then subjected to accelerated weathering conditions. The composite specimens were conditioned under ultraviolet (UV) light and water spray simultaneously for 2222 h, which corresponds to approximately 1 year of the outdoor conditions. Mechanical properties and thermogravimetric analysis (TGA) of the weathered composites were com- pared to the dry or unweathered composites. Chemical changes to the bio-based epoxy matrix and natural fber induced by photodegradation were evident as a reduction in intensity and broadening of characteristic peaks from the Fourier Transform Infrared spectroscopy (FTIR) analysis. Tensile strength and fexural strength of the weathered HSSH and HSHS declined by 7%, 13%, 25%, and 26%, respectively. Degradation efects of weathering were also visible from the lower residue of the weathered composite specimens from the thermogravimetric analysis. Despite the slight drop in impact strength, all the weathered composite specimens had good impact resistance. Furthermore, the hybrid composites exposed to weathering had nearly equivalent impact strength compared to the pure sisal and hemp-based composites under the impact load. Based on this observation, sisal/hemp fber bio-epoxy based hybrid composites are recommended for the outdoor structural applica- tions requiring impact resistance. Keywords Hemp fber · Sisal fber · Accelerated weathering * K. Senthilkumar kmsenthilkumar@gmail.com * N. Rajini rajiniklu@gmail.com * Suchart Siengchin suchart.s.pe@tggs-bangkok.org T. Senthil Muthu Kumar tsmkumar@klu.ac.in 1 Center of Innovation in Design and Engineering for Manufacturing (CoI-DEM), King Mongkut’s University of Technology North Bangkok, 1518 Wongsawang Road, Bangsue, Bangkok 10800, Thailand 2 Department of Mechanical and Process Engineering, The Sirindhorn International Thai-German Graduate School of Engineering (TGGS), King Mongkut’s University of Technology North Bangkok, 1518 Wongsawang Road, Bangsue, Bangkok 10800, Thailand 3 School of Aeronautical Sciences, Hindustan Institute of Technology & Science, Padur, Kelambakkam, Chennai, Tamilnadu 603103, India 4 Department of Mechanical Engineering, Kalasalingam Academy of Research and Education, Krishnankoil, Tamil Nadu 626126, India 5 Department of Wood Mechanics and Technology, Forestry Faculty, Istanbul University-Cerrahpasa, Bahcekoy, 34473 Istanbul, Turkey