Synthesis of Carbon Nanostructures from Residual Solids Waste Tires Ricardo Mis-Ferna ´ndez, 1 Carlos R. Rios-Soberanis, 1 Jesu ´ s Arenas-Alatorre, 2 Jose ´ A. Azamar-Barrios 3 1 Centro de Investigacio ´n Cientı ´fica de Yucata ´n, A.C., Unidad de Materiales, Calle 43, No. 103, Colonia Chuburna ´ de Hidalgo, C.P. 97200 Me ´rida, Yuc., Me ´xico 2 Instituto de Fı ´sica UNAM, Departamento de Materia Condensada, A.P. 20-364, Me ´xico D. F. 3 Centro de Investigacio ´n y de Estudios Avanzados del IPN, Unidad Me ´rida, A.P. 73, Cordemex, 97310, Me ´rida, Yuc., Me ´xico Received 28 June 2010; accepted 13 April 2011 DOI 10.1002/app.34687 Published online 22 August 2011 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: This article presents the results of the syn- thesis and morphological characterization of carbon nano- structures obtained from the decomposition of residual solid from waste tires (RSWT) in quartz tubes under reduced pressure (1.33 Pa) at 900  C for 15 min. The syn- thesis led to the formation of two phases, a fragmented solid black powder composed of multi-walled carbon nanotubes (MWCNTs), onion-type fullerenes, and spheres, and a very bright metallic dark film. Analysis by micros- copy (SEM and TEM) showed that the MWCNTs had an average diameter of approximately 25 nm and a length greater than 100 nm while the diameter of the onion-type fullerenes was found to be 8 nm. The nanospheres showed different diameters ranging from 500 nm to 1.5 lm, and some had a metallic core surrounded by layers of carbon. The infrared spectra of the nanotubes exhibited absorption bands at 1558 and 1458 cm 1 , corresponding to C¼¼C and CAC bonds, and signals at 3438 and 1080 cm 1 related to the OH and CAO groups from oxidized graphite as it was identified in the dark film. The Raman spectra of the car- bon nanostructures present D and G-bands at 1331 and 1597 cm 1 , respectively. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 1960–1967, 2012 Key words: multi-walled carbon nanotubes; MWCNTs; onion; residual solids waste tire; nanospheres INTRODUCTION Because of the massive worldwide production of tires and the technical difficulty of recycling them at the end of their functional life, discarded tires have become one of the most serious environmental prob- lems in recent years. Recycling tires can be very difficult due to the thermosetting nature of the cross- link molecular structure. Several methods for recy- cling tires have been developed such as nitric acid digestion, electric and calorific energy conversion, and pyrolysis in a vacuum or inert atmosphere. 1 The main purpose is to recover some carbon compounds and to destroy any hazardous components within the tires. Tire pyrolysis has proven to be a good method for the recovery of carbon in solids up to 93% by weight at 450  C. 2,3 In previous work, a solid powder that was obtained from car tires by pyroly- sis and thermal shock was fully characterized. It was demonstrated that a powder that was rich in carbon compounds could easily be obtained. 4 This carbon residue can be used as the main precursor during the synthesis of carbon nanostructures (i.e., carbon nanotubes (CNT), fullerenes, nanospheres, and graphite film). Murr et al., injected ground tire as the secondary carbon source during the synthesis of CNT using electric arc-discharge. 5 Nanostructures of carbon, such as CNT, fuller- enes, onions, films, and nanospheres, have attracted great academic and technological interest due to their excellent physical, mechanical, and electronics properties. 6 These materials have been extensively studied for several applications, such as electronic and thermal devices, gas storage systems (H 2 and CO 2 ), and catalytic supports, among others. 6 Carbon nanostructures are synthesized by the diffusion of carbon through a metal catalyst and its subsequent precipitation and growth as graphite filaments. In the past decade, many preparation methods for car- bon nanostructures have been developed, such as electric arc discharge, laser vaporization, hydrocar- bon pyrolysis, flame synthesis, and chemical vapor deposition (CVD), which are the three most widely used techniques. Among these three techniques, CVD is most commonly employed because of the relatively low cost of the equipment required. In Correspondence to: J. A. Azamar-Barrios (azamar@mda. cinvestav.mx). Contract grant sponsor: Mexican Council of Science and Technology (CONACYT); contract grant number: PhD Scholarship no. 167020. Journal of Applied Polymer Science, Vol. 123, 1960–1967 (2012) V C 2011 Wiley Periodicals, Inc.