Characterization and Quantification of Polymer Content in Plastic Explosives Using FT-IR Techniques

Characterization and Quantification of Polymer Content in Plastic Explosives Using FT-IR Techniques

Elizabeth da Costa Mattos (Instituto de Aeronáutica e Espaço, Brazil & Instituto de Tecnologia Aeronáutica, Brazil) and Rita de Cássia Lazzarini Dutra (Instituto de Tecnologia Aeronáutica, Brazil)
Copyright: © 2018 |Pages: 34
DOI: 10.4018/978-1-5225-2903-3.ch014


High explosives are tools used in different areas of research and are critical components in conventional and nuclear weapons. PBXs (plastic explosives) were developed to reduce the sensitivity of explosives, and are widely used in both applications, civil and military, where high performance is required. As the weapons may be used in aggressive thermal and mechanical environments, it is important to characterize the PBXs, in order to know its behavior and properties. Therefore, contributing for research of PBXs, is discussed in this chapter a methodology to characterize and to quantify the polymer content in PBX by Fourier Transform Infrared Spectroscopy (FT-IR), using the High-Performance Liquid Chromatography (HPLC) and Thermogravimetry (TG) as reference techniques to quantitative method. The proposed methodology for quantification of polymers in PBX uses the technique FT-IR of reflection ATR and UATR, being faster than the usual methodologies and eliminating the disadvantage of chemical residues generation.
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The development of space programs, drilling oil wells, etc., has designed a need to develop thermally stable explosives. The applications such explosives or explosive formulations must be reliable and safe at high temperatures. In this area, certain types of nitro compounds were given special attention because of their ability to withstand the high temperatures and low pressures found in space environments (Agrawal, 2005).

The ideal military explosive to be powerful, safe and easy to handle, can be stored for long periods of time in different climates and be difficult to detonate, unless under precisely circumstances specified (Mathieu & Stucki, 2004).

To start a detonation, a shock wave is required. This is accomplished with a small quantity of a primary explosive. Modern formulations, extremely insensitive have been developed in most countries to eliminate accidents with ammunition. Insensitive energetic compounds, new inert or energetic polymeric systems were introduced to improve the vulnerability of such weapons. The search for new energy materials with high performance characteristics is an ongoing task (Mathieu & Stucki, 2004).

The high explosives are tools used in many areas of research and are critical components in conventional and nuclear weapons. However, to be useful in most of these applications, the explosives must be manufactured to precise settings and safe.

One the most powerful explosives used in World War II was the cyclotrimethylene trinitramine (RDX). This was first prepared in 1899 by Henning (Bachmann & Sheehan, 1949), and was only used as explosive in 1920 (United States, 1979). The first discovery of cyclotetramethylene tetranitramine (HMX) date 1941 (Lukasavage, Nicolich, & Alster, 1993). Was obtained as impurity in the nitration of hexamethylenetetramine to produce RDX in small amount, approximately 10% (United States, 1979).

HMX is a high explosive, that by its high power is utilized by developed countries to carry out metal forming and energy transfer, and thus employed in plastic explosive, compressed and molded to the base of HMX (Calzia, 1969, Valença, 1998).

Pure explosive crystals are little used by the physicists and engineers because in almost all applications, the goal is to pack the greatest possible amount of explosives in a given space (high density) (Hayden, 2005). For obvious reasons, “loose explosive crystals” do not confer a high density. However, when crystals are coated with a polymeric binder, the raw material becomes very useful for the production of plastic explosives reducing sensitivity and dangerous stimuli such as shock, friction, impact, etc., the fitting them into a matrix crystals polymer (Hayden, 2005, Chen, Huang, Dai, & Ding, 2005, Singh, Felix, & Soni, 2003).

To get more energy in lower volume, it began the development of plastic explosives (PBX).

PBX is an acronym for “Plastic Bonded Explosive” (plastic explosive). A term applied to a variety of explosive mixtures which are characterized by high mechanical strength, good explosive properties (usually greater detonation velocity of 7800 m/s) excellent chemical stability, low sensitivity to shock and handling and low sensitivity to thermal initiation (Federoff & Sheffield, 1966). Many PBXs have been developed in the past half century, all usually with the goal of providing an engineering material for specific or wide range of applications [Hayden, 2005; Kim, & Park, 1999). These explosive mixtures contains a large percentage of secondary explosives such as RDX, HMX, hexanitrostilbene (HNS) or pentaerythritol-tetranitrate (PETN) in mixtures with a polymeric matrix such as polyester, polyurethane, nylon, polystyrene, various types of rubbers, nitrocellulose fluorinated polymers. In some cases, a plasticizer such as dioctylphthalate (DOP), dioctyladipate (DOA) or butyldinitrophenylamine (BDNPA) is added (Federoff & Sheffield, 1966, Thompson, Olinger, & Deluca, 2005).

PBXs were developed to reduce the sensitivity of the synthesized explosives, are widely used in both applications, civil and military, where high performance is required (Chen, Huang, Dai, & Ding, 2005).

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