Effect of Neutron Irradiation on the Structural, Mechanical, and Thermal Properties of Jute Fiber E. Sinha, 1 S. K. Rout 2 1 Department of Physics, National Institute of Technology, Rourkela 769008, Orissa, India 2 Department of Applied Physics, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, India Received 20 April 2007; accepted 30 March 2008 DOI 10.1002/app.28504 Published online 9 July 2008 in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: This article describes the effect of neutron irradiation on jute fiber (Corchorus olitorius). The jute fibers (4.0 tex) were irradiated by fast neutrons with an energy of 4.44 MeV at different fluences ranging from 2  10 9 to 2  10 13 n/cm 2 . An important aspect of neutron irradiation is that the fast neutrons can produce dense ionization at deep levels in the materials. Structural analysis of the raw and irradiated fibers were studied by small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), scanning elec- tron microscopy (SEM), and Fourier transform infrared spectroscopy. Thermal analysis carried out on the raw and irradiated fibers showed that the thermal stability of the fibers decreased after irradiation. The mechanical proper- ties of the jute fibers were found to decrease after irradia- tion. The SAXS study showed that the average periodicity transverse to the layer decreased after irradiation, which may have been due to the shrinkage of cellulosic particles constituting the fiber. The residual compressive stress devel- oped in the fiber after irradiation resulted in a decrease in crystallite size as supported by our XRD analysis. Observa- tion with SEM did not indicate any change produced in the surface morphology of the fiber due to irradiation. V V C 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 413–423, 2008 Key words: differential scanning calorimetry (DSC); fibers; mechanical properties; SAXS; X-ray INTRODUCTION Mounting concerns for the environment have sparked renewed interest in the development of bio- degradable, mechanically sound alternatives to plas- tics through the use of natural fibers. 1 Natural fibers can be used as reinforcement in a degradable poly- mer matrix and, thus, serve as inexpensive, biode- gradable, renewable, and nontoxic alternatives to glass or carbon fibers and offer high specific proper- ties such as strength and stiffness. 1 The main limita- tions of these fibers are their hydrophilic nature, low thermal resistance, and quality inconsistencies. 2 The surface treatment of fibers is mainly used to improve their properties and is, therefore, widely applied to natural fibers. 3 The influence of radiation on syn- thetic and natural polymers has been studied quite extensively over the last few decades. 4,5 Jute fiber is a natural polymer, composed 6 mainly of cellulose (58–65%), hemicelluloses (20–22%), and lignin (12– 15%). It is widely used in the textile industry, diver- sified applications in engineering, and where light weight is required, such as for building materials and structural parts for automotive applications. However, if the desired properties of jute fiber could be improved by neutron-irradiation-induced physi- cal modification, value-added products could be made from such materials. The effect of fast neutron irradiation on polymer seems interesting from both the basic and practical point of view. Fast neutrons irradiated on organic materials interact mostly with protons of the materials and produce recoil protons of high energy as a result of inelastic collisions. Therefore, the chemical effect of the fast neutron is considered to be equal to that of high- energy protons. 7 Many researchers have worked on the effects of neutron irradiation on synthetic fibers, 8–10 but much less is found in the field of natural fibers. As jute fiber is cellulosic in nature and comes under a macromolecular system, we used small- angle X-ray scattering (SAXS) to analyze some of its macromolecular structural parameters. To be spe- cific, SAXS is due to the heterogeneity of electron density occurring in matter at colloidal dimensions. When matter contains various homogeneous regions in its interior with various electron densities, SAXS takes place because of the variation of electron den- sity over a distance of the order of 10 to 1000s of angstroms. There will be no scattering if the density is uniform. For the sake of demonstration, our sys- tem was considered a two-phase (cellulose and void) one, and the square of electron density differ- ence took about 100 times the value of that between the crystalline and amorphous celluloses. Hence, we treated jute as a two-phase system with the cellulose and the void as its two phases. This phenomenon Journal of Applied Polymer Science, Vol. 110, 413–423 (2008) V V C 2008 Wiley Periodicals, Inc. Correspondence to: E. Sinha (elasinha@rediffmail.com).