Enhanced Scratch Resistance of Nanocomposite Gelatin Films
- PDF / 795,435 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 81 Downloads / 231 Views
Enhanced Scratch Resistance of Nanocomposite Gelatin Films Quan Chen, Linda S. Schadler, Richard W. Siegel Rensselaer Nanotechnology Center, Rensselaer Polytechnic Institute, Troy, NY 12180, U.S.A. Glen C. Irvin Jr., John Mendel Eastman Kodak Company, Rochester, NY 14652, U.S.A. ABSTRACT Nanocomposites were made using deionized gelatin filled with well-dispersed nanoscale alumina particles. Scratch tests on the nanocomposite films showed substantially improved scratch resistance. Tensile tests revealed increases in both modulus and tensile strength of the nano-filled gelatin films accompanied by a decrease in strain-to-failure. The increase in modulus and strength reduced the degree of plastic deformation during scratch testing, but the onset of periodic cracking in the scratch track was unaffected. Optical transmittance measurements of the gelatin composite showed that the films retained transparency in the visible light range. INTRODUCTION Gelatin has been used in photographic emulsions for about 100 years and plays a variety of important roles. Its chief functions are as a ripening agent, sensitizer, halogen acceptor, binder and protective coating. One limitation of gelatin films as a protective layer is their low scratch resistance. Scratches not only compromise the aesthetics of the films, but block light transmission to the light sensitized layer. One method for improving the scratch resistance of a polymer is to improve its mechanical properties by adding fillers. Traditional micron-scale fillers cause significant light scattering because their size is comparable to visible light wavelengths, thus reducing the transmission of light. Recently, polymers filled with nanoscale particles have received considerable attention. Their small size creates the opportunity to change the mechanical properties of a polymer without altering its optical transmission [1]. In addition, the large interfacial area can result in tremendous improvements in mechanical properties as well as barrier properties [2,3]. For example, the addition of 5 wt% of alumina to polymethylmethacrylate results in an order of magnitude improvement in ductility [4]. The present study is a continuation of our previous research, in which we have taken advantage of the high optical transmittance of alumina filled gelatin to create nanoscale composites with enhanced scratch resistance for use as clear protective coatings [5]. In this paper, two distinct scratch damage features observed in scratch test are shown. The test results for modulus and tensile strength, which are critical factors in determining the scratch deformation of film materials, are introduced. Also some further test results on topcoated film samples subjected to real application are presented. MATERIALS AND EXPERIMENTAL METHOD Gelatin is manufactured from the protein collagen; its primary sources are cattle hides and bones [6]. The experimental material used in this paper was a deionized form of this gelatin provided by Eastman Kodak Company. The nanoscale alumina was produced by Nanopha
Data Loading...
