Research Article Nanocomposites of NR/SBR Blend Prepared by Latex Casting Method: Effects of Nano-TiO 2 and Polystyrene-Encapsulated Nano-TiO 2 on the Cure Characteristics, Physical Properties, and Morphology Anyaporn Boonmahitthisud, 1 Peeraphong Pokphat, 2 Phasawat Chaiwutthinan, 3 and Saowaroj Chuayjuljit 1 1 Department of Materials Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Tailand 2 Program of Petrochemistry and Polymer Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Tailand 3 MTEC, National Science and Technology Development Agency (NSTDA), Tailand Science Park, Khlong Luang, Pathum Tani 12120, Tailand Correspondence should be addressed to Anyaporn Boonmahitthisud; anyaporn.b@chula.ac.th Received 22 November 2016; Accepted 12 March 2017; Published 29 March 2017 Academic Editor: R. Torrecillas Copyright © 2017 Anyaporn Boonmahitthisud et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Nanocomposites of 80/20 (w/w) natural rubber (NR)/styrene butadiene rubber (SBR) blend with four loadings of either nanosized titanium dioxide (nTiO 2 ) or polystyrene-encapsulated nTiO 2 (PS-nTiO 2 ), ranging from 3 to 9 parts by weight per hundred of rubber (phr), were prepared by latex casting method. Te PS-n TiO 2 synthesized via in situ diferential microemulsion polymerization displayed a core-shell morphology (nTiO 2 core and PS shell) with an average diameter of 42 nm. Te cure characteristics (scorch time, cure time, and cure rate index), mechanical properties (tensile properties, tear strength, and hardness), thermal stability, glass transition temperature, and morphology of the prepared nanocomposites were quantifed and compared. Te results showed that the cure characteristics of all the nanocomposites were not signifcantly changed compared to those of the neat NR/SBR blend. Te inclusion of an appropriate amount of either n TiO 2 or PS-nTiO 2 into the NR/SBR blend apparently improved the tensile strength, modulus at 300% strain, tear strength, hardness, and thermal stability but deteriorated the elongation at break of the nanocomposites. Based on diferential scanning calorimetry, the glass transition temperature of all the nanocomposites was similar to that of the neat NR/SBR blend. Moreover, the morphology of the PS-nTiO 2 -flled rubber nanocomposites fractured surface analyzed by scanning electron microscopy showed an improvement in the interfacial adhesion between the rubber phase and the nanoparticles. 1. Introduction High-performance elastomeric materials have been produced by developing multicomponent systems in terms of rubber blend and/or rubber nanocomposites [1–16]. Blending of rub- bers is an important technique to improve certain properties not inherent in a single rubber, while incorporating an inor- ganic nanofller (nanosized fller) even at a very low loading (less than 10 wt%) into rubber matrix by physical mixing has attracted considerable interest for both scientifc challenges and industrial applications due to their high-performance properties [2, 4–9, 11–16]. Natural rubber (NR) is one of the most important natural biosynthesis polymers, according to its high elasticity, resilience and mechanical properties, low heat build-up and cost, and good formability [1, 4–9]. NR can exhibit higher tensile and tear strength than synthetic rubbers due to its ability to undergo strain crystallization [1, 6–9]. However, NR sufers from poor weathering, ozone, oil, and thermal resistance because of its nonpolarity and high unsat- uration [9, 10]. Consequently, NR is normally modifed by simple blending with commercially available rubbers and/or fllers to improve its physical properties, thermal stability, and Hindawi Journal of Nanomaterials Volume 2017, Article ID 7676158, 11 pages https://doi.org/10.1155/2017/7676158