Energy Measuremenrts And Spectroscopic Studies On Optical Radiation From RDX Thermally Explosive Process

As an important product, energetic materials have found wide application in both military and civilian industries. For many years, related research has been highly confined to the materials’physical and chemical properties as well as their explosion and combustion processes since they concern the materials’reliability, safety and performance. However, this dissertation lays focus on their optical properties in hope of enriching people’s understanding about them.As one channel of energy release in explosive reaction, optical radiation sends a variety of information about the physical and chemical changes that occur in energetic materials during the explosion process. Studies on its spectroscopy and generating mechanism have so far yielded many results. However, a few questions still remain unanswered. Unlike the materials’physical and chemical parameters such as work ability, heat energy and reaction energy, optical radiation has yet to be subjected to quantified measurement, which makes incomplete our knowledge about the energy release in the explosion processes. Therefore, light propagation and adsorption in energetic materials and their coating is of great interest to us, since it is related to the materials’stability and security under the optical radiation.To explore the above questions, a nitro-energetic material named RDX is chosen as our experimental material. To reveal the relationship between its mass and optical radiation energy in the explosion process, a preliminary measurement of its optical radiation energy is conducted by using spectrum technology. In addition, quantum chemical calculation is performed on RDX and its coating material Polyvinylidene Fluoride (PVDF) to draw out their peculiar optical properties. Also, effects of optical radiation of different wavelengths on them are discussed.The major work and findings in this dissertation are listed as follows:1. Different masses of RDX are subjected to a thermal shock test in a vacuum quartz tube. The probabilities of the sample’s thermal decomposition, combustion and explosion are obtained. A material analysis of RDX solid residue after its thermal decomposition shows they are nanoscale carbide particles with an average size of15.8nm, mainly ranging from8.80nm to17.66nm. And their molecular formula may be C74N23O3. In addition, GC-MS analysis (chromatograph and mass spectrometer analysis) of gaseous products from the thermal decomposition suggests the gas contains N-oxide, CH4, C2H4, C3H6and other components. 2. The explosion and combustion spectra of RDX are measured within the spectroscopy system. Their spectral signatures suggest that the two processes are by nature the same and explosion is actually a violent combustion reaction. The relative intensity curve of explosion spectrum is obtained in239nm-871nm wavelength range. Moreover, our explosion spectrum is close to other experimental results in500nm-800nm wavelength range, lending more reliability to our findings.3. If electron transfer between molecules can form optical radiation in the explosion process, its spectral lines agree with our measured results. Take423nm,554nm,589nm and768nm lines for instance, our quantum chemical calculation shows that they are not necessarily produced by impurity atoms, and as a matter of fact electron transfer can play a part.4. The photomultiplier tube is used as the energy detector in our optical radiation energy measurement system. It is found that when RDX detonates in261nm-650nm wavelength range, its mass and optical radiation energy are in negative exponential relation. The radiation energies are6.24MJ/kg and1.17MJ/kg when the masses are20mg and35mg, respectively. If the mass is much more than35mg, the radiation energy tends to1.26MJ/kg. And the self-combustion of RDX can release optical radiation energy of about4.93MJ/kg in a closed vacuum space.5. The electronic structures and Optical properties of RDX and PVDF are calculated by first principles methods based on density functional theory. The UV light in175nm-400nm wavelength range is transparent for PVDF, but is heavily absorbed by RDX. Therefore in the above wavelength range, PVDF fails to provide RDX with’light protection’, granting easy access to detonation.