SURFACE MODIFICATION OF NANO TITANIUM DIOXIDE (TiO 2 ) BY CATIONIC SURFACTANTS AND INVESTIGATION OF ITS EFFECTON THE PROPERTIES OF NATURAL RUBBER (NR) NANOCOMPOSITES KUMARJYOTI ROY,DEBDAS SIKDAR,SWAPAN KUMAR MANDAL,SUBHAS CHANDRA DEBNATH * DEPARTMENT OF CHEMISTRY,UNIVERSITY OF KALYANI,KALYANI,NADIA 741235(W.B), INDIA RUBBER CHEMISTRY AND TECHNOLOGY, Vol. 00, No. 0, pp. 000–000 (0000) ABSTRACT We investigate the reinforcing effects of both unmodified and surface modified nano titanium dioxide (TiO 2 ) on the cure, mechanical, and thermal properties of natural rubber (NR) nanocomposites. The surface of nano TiO 2 is modified by cationic surfactants cetyltrimethylammonium bromide (CTAB) and tetraethylammonium bromide (TEAB). The surface modification of nano TiO 2 is characterized by Fourier transform infrared (FTIR) spectra and Field emission scanning electron microscopy (FESEM). The result reveals that surface modified nano TiO 2 is much more efficient in improving the resulting properties of NR nanocomposites in comparison with unmodified nano TiO 2 . The excellent improvement in the properties of surface modified nano TiO 2 /NR composites is due to the better hydrophobicity and uniform dispersion of modified nano TiO 2 within the NR matrix, as confirmed from morphological analysis. CTAB is much more effective than TEAB with respect to the properties of nano TiO 2 based NR composites. [doi:10.5254/rct.19.84831] INTRODUCTION Owing to its excellent mechanical properties and hardness, natural rubber (NR) is an irreplaceable constituent of many products used in various industrial and commercial sectors. The majority of natural rubber is used in automobile tires and tubes. NR is also suitable material in various non-tire items, like hoses, footwear, balloons, sports goods, erasers, toys, etc. The exceptional mechanical properties of NR result from several factors, such as self-induced crystallization, highly stereoregular microstructure, the rotational freedom of the a-methylenic C– C bonds, and high elasticity due to the entanglements resulting from the high molecular weight. 1 Despite the attractive mechanical properties of NR, it is generally applied along with reinforcing filler in order to achieve optimum properties required in any particular application. 2 Carbon black and silica are the most commonly used fillers in rubber engineering products. However, the reinforcing effects of both the fillers are effectively reduced because of their large particle size, which causes agglomeration within the rubber matrix. 3 On the other hand, due to their large specific surface area, nano fillers are uniformly dispersed within the rubber matrix. 3 As a result, introduction of very small amount of nano fillers into the rubber matrix is an essential approach to achieve suitable mechanical and physical properties of rubber composites. 3 In recent decades, the applications of various nano fillers have received much attention in the industrial field of rubber nanocomposites. Several research articles have been reported related to rubber nanocomposites based on some commonly used nano fillers, such as carbon nano tube, 4–6 nano clay, 7–9 nano calcium carbonate, 10–12 etc. The efficiency of nano fillers in improving the properties of rubber nanocomposites is mainly related to their degree of dispersion within the rubber matrix. 13 But the hydrophilic nature of nano fillers hampers their uniform distribution within the hydrophobic rubber matrix. 13–15 Thus, surface modification of nano fillers is a mandatory step for its wide application in the rubber industry. The application of various surfactants for modifying the surface of nanoparticles has been reported recently by different researchers. 15–18 Taghvaei-Ganjali et al. 15 described the surface *Corresponding author. Ph: þ 91-33-2582-8750(O) [Ext. 305]; email: debnathsubhas@yahoo.com 0