Effect of Surface Modification of Jute Fiber on the Mechanical Properties and Durability of Jute Fiber- Reinforced Epoxy Composites Anna Dilfi K.F., 1,2,3 Aiswarya Balan, 1,2,3,4 Hong Bin, 1,2,3 Guijun Xian , 1,2,3 Sabu Thomas 4 1 Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education (Harbin Institute of Technology), Harbin, 150090, China 2 Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology, Harbin Institute of Technology, Harbin, 150090, China 3 School of Civil Engineering, Harbin Institute of Technology, Harbin, 150090, China 4 Centre for Nanoscience & Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala, India In this article, the effect of various surface modifica- tions on the properties and durability of jute fiber- reinforced epoxy composites (JFRECs) was studied. Jute fiber was surface modified to improve its compat- ibility with the hydrophobic epoxy matrix. The surface modifications investigated include alkali treatment, silane treatment, and the combined effect of alkali and silane treatments. JFRECs were prepared by vacuum- assisted resin infusion (VARI) process. The surface topography of the untreated and modified fibers was examined by means of scanning electron microscopy (SEM). The mechanical properties, such as flexural properties and interfacial shear strength (IFSS), and thermomechanical properties, such as dynamic mechanical analysis (DMA) of the composites of untreated and modified fibers were determined. The durability studies such as water uptake as well as the effect of moisture on the mechanical and thermome- chanical properties of the untreated and combined chemically treated fiber composites were examined. It was found that the combined modification provided better mechanical and thermal properties of compo- sites in comparison with untreated composite due to strong fiber–matrix interfacial adhesion. The rate of water absorption for chemically treated fiber compos- ite was found to be lesser than the untreated fiber composite. There was a significant drop in the mechanical and thermomechanical properties of the composites after exposure to moisture. This could be due to the fiber degradation and de-bonding at the interface during the immersion of the composite sam- ples in water. POLYM. COMPOS., 00:000–000, 2018. V C 2018 Society of Plastics Engineers INTRODUCTION As an alternative to man-made fibers, natural plant- based cellulosic fibers such as ramie, flax, hemp, sisal, jute, henequen, kenaf, bamboo, and pineapple are studied to reinforce composites. Natural fiber-reinforced compo- sites have been used for many applications, such as auto- motive components, aerospace parts, sporting goods, and construction industry. Natural fibers have many advan- tages over synthetic fibers, for instance, environmental friendliness, cost-effectiveness, light weight, biodegrad- ability, and acceptable mechanical properties [1, 2]. How- ever, these fibers are highly hydrophilic in nature. The hydrophilic nature of natural fibers is the main drawback for their application as reinforcements in composites. The poor resistance of natural fibers toward moisture leads to the incompatibility and poor wettability with hydrophobic polymer matrices [3]. Several chemical and physical mod- ification methods [4, 5] of natural fibers have been stud- ied by researchers in order to improve the compatibility with hydrophobic polymer matrices. The use of compati- bilizers [6], surface modification techniques such as alkali treatments [7–9], acetylation [10], use of maleic anhy- dride modified polypropelene (PP) [11, 12], or graft poly- merization [13], etc. have been reported by researchers. Surface chemical modification with coupling agents is usually applied to improve the wetting of lignocellulosic Correspondence to: G. Xian; e-mail: gjxian@hit.edu.cn Contract grant sponsor: National Key Research and Development Pro- gram of China; contract grant number: 2017YFC0703007; contract grant sponsor: National Natural Science Foundation of China; contract grant numbers: 51178147, 51478145. DOI 10.1002/pc.24817 Published online in Wiley Online Library (wileyonlinelibrary.com). V C 2018 Society of Plastics Engineers POLYMER COMPOSITES—2018