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Title: Effect of homolog doping on surface morphology and mass-loss rates from PETN crystals. Studies using atomic force microscope and thermo-gravimetric analysis

Pentaerythritol tetranitrate (PETN) is an important energetic material and its performance as a secondary explosive depends strongly on the density as well as flow porosity of powdered material, which in turn is governed by the size and surface properties of the PETN crystallite particles. Historically there has been evidence that the surface properties of PETN particles can be strongly influenced by the presence of homolog impurities of PETN, in particular, dipentaerythritol hexanitrate (diPEHN) and tripentaerythritol octanitrate (triPEON), although not many systematic studies characterizing such influence exist. In this work we employ thermogravimetric analysis (TGA) to measure mass-loss rates at elevated temperatures and show that doping with a small amount of diPEHN and triPEON can reduce the mass-loss rate from PETN single-crystal surfaces by as much as 35 % as compared to undoped crystals. Arrhenius plots of mass-loss rates as a function of temperature suggest that the reduction in evaporation is not due to the change in activation barrier of the molecular evaporation process, but perhaps due to the impedance to the receding motion of the steps by the immobile impurities on the surface. Removal of surface impurities through gentle washing with ethanol leads to enhanced mass-loss rate relative to puremore » PETN suggesting a roughened surface morphology. Some surface roughening in doped crystals is supported by Atomic force microscopy (AFM) images of growth layers that show evidences of growth layer stacking and rough edges. Furthermore, we find that a larger amount of impurity added to the original solution does not necessarily lead to a more highly doped crystal, which could perhaps be interpreted as PETN crystals being able to accommodate only up to a certain weight percent of homolog impurities.« less
Authors:
 [1] ;  [2] ;  [2] ;  [1] ;  [1]
  1. Texas Tech Univ., Lubbock, TX (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
OSTI Identifier:
1237571
Report Number(s):
LLNL-JRNL--579952
Journal ID: ISSN 0721-3115
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Propellants, Explosives, Pyrotechnics
Additional Journal Information:
Journal Volume: 39; Journal Issue: 1; Journal ID: ISSN 0721-3115
Publisher:
Wiley
Research Org:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY single crystal; PETN; doping; impurities; mass-loss rate; morphology