Effect of Nanoscale Species on the Behavior of Polymer Nanocomposites Subjected to Laser Pulse Heating
- PDF / 549,419 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 113 Downloads / 213 Views
Effect of Nanoscale Species on the Behavior of Polymer Nanocomposites Subjected to Laser Pulse Heating Stephen F. Bartolucci1, Jeffrey Warrender1, Karen Supan2, Jeffery Wiggins3, Lawrence LaBeaud3 1
US Army Armaments Research Development and Engineering Center – Benét Laboratories, Watervliet, NY 12189, U.S.A. 2
Norwich University, Department of Mechanical Engineering, Northfield, VT, 05663, U.S.A. 3
School of Polymers and High Performance Materials, University of Southern Mississippi, Hattiesburg, MS, 39406 U.S.A.
ABSTRACT Polymers and polymer nanocomposites have been studied under conditions of extremely high heating rates. Traditionally, these materials have been examined by the flammability research community using methods which have heating rates on the order of 10 degrees C/min. In this study, we have examined how polypropylene-nanoclay (montmorillonite) and polypropylene-carbon nanotube nanocomposites behave subjected to heating rates on the order of one million degrees C/min when irradiated with a 1064 nm Nd-YAG variable pulse millisecond laser. Time-resolved temperature data and mass loss data was collected for each sample as well as post-mortem surface characterization using spectroscopy and electron microscopy. The analysis shows that the nanospecies are effective in providing a protective barrier that decreases the amount of degradation and mass loss to the underlying polymer material. The effect is clearly seen after irradiating with a single pulse and multiple pulses. A comparison between the performance of the nanoclay and carbon nanotube composites is given.
INTRODUCTION Incorporation of nanoscale materials, including clays and carbon nanotubes, into polymers such as polypropylene has been extensively studied for many years [1-11]. These nanocomposites commonly exhibit improved mechanical properties, increased thermal stability, and reduced flammability. Layered aluminosilicate, such as montmorillonite nanoclay, has been known to promote the formation of a protective char layer in a polymer. This limits the heat transfer into the polymer and the escape of degrading polymer mass from the material, slowing the thermal degradation of the polymer. Gilman et al. [1] demonstrated that nanoclay can provide thermal stability and reduced flammability of a polymer during heating. In addition to nanoclays, carbon nanotubes have also been shown to add thermal stability to a polymer subjected to high temperatures. Kashiwagi et al. [2] showed that well-dispersed carbon nanotubes can form a network layer that slows the thermal degradation of PMMA.
Thermal stability tests have traditionally been performed under slow heating conditions, at heating rates of about 20C/minute or below. In contrast, some applications may expose these materials to heating rates that are orders of magnitude larger. It is unknown how these materials will respond under brief, but intense thermal loading, and whether the polymer nanocomposites that are optimized with respect to thermal stability will show similarly superior performanc
Data Loading...
