134 POLYMER COMPOSITES, APRIL 2004, Vol. 25, No. 2 1. INTRODUCTION N atural fibers are important because of the interest in their use in the development of low cost “eco- friendly” natural fiber-composites. Indeed, the mechan- ical properties of natural fibers containing cellulose in composite materials (1, 2) are the subject of current international research projects. This is especially im- portant if such fibers are residues of agroindustrial pro- cesses and if their raw-properties are acceptable for composites, making their purification to pure cellulose unnecessary. Examples of such natural fibers are resi- dues from pineapple (3), banana (4), rice (5), coconut (6) and sugar cane (7) processing. From society’s point of view and owing to the pressure of environmental groups leading to new environmental regulations, the production of natural fiber-composites has gained great attention, since it is recognized that natural fibers are cheap, highly available and renewable. Natural cellu- losic fiber-polypropylene composites are being used in the automobile industry, and their usage is growing in general (8). One of these natural materials available in great quantities is sugar cane bagasse, a solid residue obtained after the extraction of the juice of sugar cane Improvement of the Interfacial Compatibility Between Sugar Cane Bagasse Fibers and Polystyrene for Composites EDGAR GARCÍA-HERNÁNDEZ 1 , ANGEL LICEA-CLAVERÍE 1 * , ARTURO ZIZUMBO 1 , ALBERTO ALVAREZ-CASTILLO 2 , and PEDRO J. HERRERA-FRANCO 3 1 Instituto Tecnológico de Tijuana Centro de Graduados e Investigación A.P. 1166, (22000) Tijuana, Baja California, México 2 Instituto Tecnológico de Zacatepec División de Estudios de Posgrado e Investigación y Departamento de Ingeniería Química y Bioquímica A.P. 45, Calzada Tecnológico 27, C.P. 62780, Zacatepec, Morelos, México 3 Centro de Investigación Científica de Yucatán, A.C. Unidad de Materiales Calle 43 #130, Col. Chuburná de Hidalgo, (97200) Mérida, Yucatán, México Sugar cane bagasse fibers were modified by surface treatments using either physical or chemical methods in order to improve their adhesion to polystyrene ma- trices. The surface treatment methods used were alkaline treatment, treatment with silane coupling agents, physical coating with polystyrene and grafting of poly- styrene with and without crosslinker. Fiber modifications were monitored by Fourier Transform Infrared Spectroscopy (FTIR), Differential Thermal Analysis coupled with Thermogravimetric Analysis (DTA-TGA) and Scanning Electron Microscopy (SEM). On the other hand, the improvement of the adhesion between sugar cane modified fibers and polystyrene was assessed by micromechanical pull-out and by macrome- chanical Iosipescu tests. It was found, from Interfacial Shear Strength values (IFSS), that substantial improvements in fiber-matrix compatibility were achieved. According to micro- and macromechanical test results, the IFSS increased for all treated fibers as compared to non-treated fibers. Particularly, both the coating the fibers or grafting with polystyrene using crosslinker resulted in substantial adhe- sion improvement to the polystyrene matrix in comparison with the non-treated fibers and fibers treated by alkaline and silane methods only. Polym. Compos. 25:134–145, 2004. © 2004 Society of Plastics Engineers. *To whom correspondence should be addressed. E-mail: aliceac@tectijuana.mx © 2004 Society of Plastics Engineers Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/pc.20011