Chemical, Mechanical and Electrical Properties of Glassy Polymeric Carbon
- PDF / 203,033 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 94 Downloads / 208 Views
0929-II04-08
Chemical, Mechanical and Electrical Properties of Glassy Polymeric Carbon Iulia C. Muntele, Claudiu I. Muntele, Renato Minamisawa, Bopha Chhay, and Daryush Ila Center for Irradiation of Materials, Alabama A&M University, 4900 Meridian Street, Normal, AL, 35762
ABSTRACT Glassy Polymeric Carbon (GPC) is obtained by a molding technique, in various shapes, from a phenolic resin precursor. The heat treatment of the precursor is achieved in three stages up to 1000 °C. Similar GPC materials produced in our laboratory displayed large strain to failure ratio, small thermal expansion coefficient and low density. Like all carbon forms, is attacked by oxygen, especially atomic oxygen. Nevertheless the kinetics for reaction with atmospheric oxygen is very slow. We investigated the composition and structural changes of the phenolic precursor as a function of temperature and evaluated material’s stability when exposed to high temperatures in presence of hydrogen (H2) or oxygen (O2). INTRODUCTION GPC is a polymer obtained by pyrolysis of resols (in our case formaldehyde resin provided by Georgia Pacific, GP 387G84 Resi-Lam Phenolic Laminating Resin). GPC is a unique material, relatively chemically inert (at room temperature), and biocompatible [1]. GPC can withstand high temperature and corrosive environments, with applications in nuclear reactors and space industry (nuclear fuel cells, heat shied for thermal protection systems). A vast amount of literature [1-5] is available in regard with the use of heat-treated phenolic resin and its applications in construction industry for coatings, adhesives, polymer flame-retardants, and composites. Some desirable properties of this material are low density (1 g/cm3), low thermal conductivity (0.238-1.428 W/mK), low thermal expansion coefficient (10-8 K-1), high critical oxygen index (difficult to ignite and maintain a burning condition) [6]. One indication of material’s thermal stability can be inferred from the fact that its chemical kinetics at any given temperature moves to completion very quickly and subsequent exposure at the same temperature will not induce further structural change [1]. This thermal stability suggests that the material will retain its structural integrity and mechanical and physical properties under adverse conditions. The objective of this study was to obtain and characterize the composition and structural changes of pure GPC samples in extreme environments.
EXPERIMENT GPC sample preparation: liquid resol was diluted 1:1 dilution ratio with ethyl alcohol, sonicated, kept 3 hours at gelling temperature, molded in the desired shape and gelled for 5 days at 75 °C. After removal from mold the samples are pyrolyzed up to 1000 °C according with a designed heat treatment [7] program for 170 hours. Samples prepared at different heat treatment stages (75, 200, 500, 700 and 1000 °C) were characterized using Rutherford Backscattering Spectrometry (RBS), FTIR/ATR Spectroscopy, Raman Spectroscopy, Residual Gas Analysis (RGA), mechanical characterization, and res
Data Loading...
