Preparation of structurally-colored aromatic polyamides and their physicochemical properties

Conclusions One-, two-, and three-stage methods of preparing structurally-dyed aromatic polyamides with chromophoric fragments in the chain have been investigated.It has been shown that the molecular weight of the polymers obtained and the proportion of chromophores bound into their chain is determined by the reactivity of the starting diaminoanthraquinones.It has been found that the introduction of anthraquinone units into the poly-m-phenylene isophthalamide chain has little effect on the structure or basic physicochemical properties of the polyamide, but gives the polymer a uniform and regular coloration.Structural dyeing of poly-m-phenylene isophthalamide with fragments of 1,5-DAAQ or 4,8-DADHAQ increases the resistance of the polyamide fibres to UV irradiation.The authors express their thanks to Yu. Ya. Shavarin and N. M. Bol'bit for performance of the fibre irradiation, and also to B. A. Tsaplin for thermomechanical testing of the fibres.L. Ya. Karpov NIFKhI, Moscow. VNIISV, Tver'. Translated from Khimicheskie Volokna, No. 2, pp. 24–27, March–April, 1992.     

Initiation of the explosive decomposition of pentaerythritol tetranitrate with ultradispersed particle additives by laser pulses

The explosive decomposition threshold of pentaerythritol tetranitrate was studied depending on the concentrations of ultradispersed Al particles and Ni-C and Al-C mechanocomposites in the samples. It was found that the critical pulse energy density W _0.5, which corresponds to a 50% probability of explosion, reached a minimum value at additive concentrations of 0.1?C0.3 wt %: W _0.5 = 1.4, 5, or 4 J/cm² for Al, Ni-C, or Al-C, respectively.     

Survey of Methods for Automated Code-Reuse Exploit Generation

Programming and Computer Software - This paper provides a survey of methods and tools for automated code-reuse exploit generation. Such exploits use code that is already contained in a vulnerable...     

Influence of the mass fraction of oxide in aluminum nanoparticles on the explosive decomposition threshold and light absorption efficiency in PETN-based compounds

Pulsed laser initiation is used to experimentally investigate the thresholds of explosive decomposition of PETN-based compounds with aluminum nanoparticle inclusions depending on the core-shell (Al/Al₂O₃) mass ratio in the particle. It is found that, with decreasing mass fraction of Al from 74 to 13%, the explosive decomposition threshold increases by a factor of 12.5. Light absorption efficiency calculations for the core-shell system performed by the Aden-Kerker method for Al/Al₂O₃ inclusions in PETN show that this efficiency decreases with decreasing mass of metal in the particle. The experimental and theoretical results can be regarded as an additional confirmation of the hot-spot concept of laser initiation of PETN containing nanoscale inclusions of metals.     

Spectroscopic investigation of polymers dyed with fluorescent dyes — Naphthalimide derivatives

Conclusions 1. Naphthalimide derivatives are promising for the preparation of dyed and fluorescing polyamide, and especially acetate fibres. Thereupon dyeing of the fibres in bulk is a more economical and ecologically clean method than dyeing from solutions.2. The optimum dye concentration in the fibre — about 0.5% by weight — at which the fibre acquires a bright color and fluoresces intensively has been determined.Scientific Research Institute of Physical Chemistry, Moscow. Translated from Khimicheskie Volokna, No. 5, pp. 16–18, September–October, 1993.     

Laser initiation of PETN-based composites with additives of ultrafine aluminium particles

This paper describes the study on the dependence of the critical energy density of the explosive decomposition of PETN on the mass concentration of the additives of ultrafine Al particles (100–120 nm) in the range of 0.025–1% under the influence of the first and second harmonics of a neodymium laser (12 ns, 1064 and 532 nm). It is shown that the critical energy of the explosion initiation by the first and second harmonics of the laser radiation reaches a minimum value at the same absorption rates, but different concentrations of additives. The photoacoustic method is used to show that, as the laser energy radiation is absorbed, the pressure amplitude in the heated layer reaches a maximum value when the concentration of additives corresponds to the minimum value of the critical energy density.     

Measuring the temperature of PETN explosion products with iron inclusions

The spectral-kinetic characteristics of luminescence of PETN with iron nanoparticle inclusions are measured in real time in the case of a laser initiated explosion (the wavelength is 1064 nm, and the pulse duration is 14 ns). During the action of the laser radiation pulse, the luminescence of the samples is observed, and the explosive decomposition occurs in a microsecond time interval. The spectral pyrometry method is used to establish the thermal nature of explosive luminescence. The explosion temperature is estimated to be 3400 ±100 K.     

Effect of radiation treatment on silver azide sensitivity

A novel technique is proposed for studying the effect of radiation treatment on sensitivity of energetic materials, based on irradiation of specimens by a series of pulses on an electron accelerator. Data obtained in experiments with silver azide crystals are reported. The explosion probability in irradiated specimens is shown to be a nonmonotonic function of the radiation dose, exhibiting a rise for low doses and a fall for high doses. The experimental data obtained agree with the divacancy model for heavy metal azide initiation. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 2, pp. 116–120, March–April, 2006.     

Effect of radiation treatment on the explosive conduction kinetics of heavy metal azides

A study is performed of the effect of preliminary irradiation on the explosive conduction kinetics of whisker crystals of silver and lead azides under laser initiation. The rate of explosive decomposition of lead azide is shown to be a nonmonotonic function of the radiation dose, exhibiting a rise at low doses (tens of thousands of radians) and a fall at high doses (hundreds of thousands of radians). The results are analyzed using the previously proposed model of charge exchange of reaction centers during initiation. It is concluded that this model can be used to describe the effect of radiation treatment on the early stages of explosive decomposition. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 6, pp. 78–83, November–December, 2007.     

Laser initiation of PETN containing light-scattering additives

We suggest to improve the efficiency of the laser initiation of pentaerythritol tetranitrate (PETN) by increasing the photon trajectory length in the initiated material due to multiple scattering. The proposed method has been experimentally verified. The introduction of a light-scattering additive (0.5 wt % MgO) into PETN decreases the initiation threshold by a factor of ∼3.5 for the first harmonic radiation of a neodymium laser (1060 nm).