Compatibility of energetic plasticizers with the triblock copolymer of polypropylene glycol-glycidyl azide polymer-polypropylene glycol (PPG-GAP-PPG)

Glycidyl azide polymer (GAP) is well known as an energetic prepolymer, but its application as a binder in propellants is limited due to its relatively high glass transition temperature and relatively poor mechanical properties. Copolymerization of GAP with polypropylene glycol (PPG) has been shown to improve GAPs properties because of the good thermal and mechanical properties of PPG. In this research we synthesized triblock copolymer of PPG-GAP-PPG and the compatibilities of this copolymer were investigated with energetic plasticizers (20% w/w) n-butyl nitroxyethylnitramine (BuNENA), trimethylolethane trinitrate (TMETN), and butanetriol trinitrate (BTTN) by solubility parameter, differential scanning calorimetry (DSC), rheological analysis, scanning electron microscopy (SEM) and vacuum stability test (VST). The DSC results showed that BuNENA had better compatibility with the triblock copolymer in comparison to TMETN and BTTN. It reduced the Tg of PPG-GAP-PPG from −58 to −63 °C. The rheological analysis was in good agreement with the DSC results obtained for the compatibility of the plasticizers. In the case of the addition of 20% w/w BuNENA, the viscosity of copolymer/plasticizer decreased from 550 to 128 mPa s, indicating appropriate compatibility of plasticizer with the copolymer. SEM images showed a better distribution of BuNENA in the copolymer matrix.

Kinetic Analysis of the Thermal Decomposition of Polymer-Bonded Explosive Based on PETN: Model-Fitting Method and Isoconversional Method

This work investigates kinetics and thermal decomposition behaviors of pentaerythritol tetranitrate (PETN) and two polymer-bonded explosive (PBX) samples created from PETN (named as PBX-PN-85 and PBX-PP-85) using the vacuum stability test (VST) and thermogravimetry (TG/DTG) techniques. Both model-free (isoconversional) and model-fitting methods were applied to determine the kinetic parameters of the thermal decomposition. It was found that kinetic parameters obtained by the modified Kissinger–Akahira–Sunose method (using non-isothermal TG/DTG data) were close to those obtained by the isoconversional and model-fitting methods that use isothermal VST data. The activation energy values of thermal decomposition reactions were 125.6–137.1, 137.3–144.9, and 143.9–152.4 kJ·mol−1 for PBX-PN-85, PETN, and PBX-PP-85, respectively. The results demonstrate the negative effect of the nitrocellulose-based binder in reducing the thermal stability of single PETN, while the polystyrene-based binder seemingly shows no adverse influence on the thermal decomposition of PETN in our presented PBX compositions.

Compatibility Study of 1,1-Diamino-2,2-Dinitroethene (FOX-7) with Some Energetic Materials

1,1-diamino-2,2-dinitroethene (FOX-7) is a novel explosive with low sensitivity and high performance. The compatibility of FOX-7 with nine common energetic materials including hexanitrohexazaisowurtzitane (CL-20), cyclotetramethylenetetranitramine (HMX), cyclotrimethylenetrinitramine (RDX), 3,4-dinitrofurazanfuroxan (DNTF), 3-nitro-1,2,4-triazol-5-one (NTO), hexanitrostilbene (HNS-II), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), 2,4,6-triamino-1,3,5-trinitrobenzene (TATB), and 2,4,6-trinitrotoluene (TNT) were tested by differential scanning calorimetry (DSC) and the vacuum stability test (VST) as the thermal technique and X-ray diffractometry (XRD) as a nonthermal technique. DSC measurements showed that the binary systems of FOX-7/CL-20, FOX-7/HMX, FOX-7/NTO, and FOX-7/TNT were compatible in grade of A, the systems of FOX-7 with heat-resistant explosives including HNS-II, LLM-105, and TATB were compatible as well in grade of A-B, and the binary systems of FOX-7/DNTF and FOX-7/RDX had poor compatibility. VST results indicated that FOX-7 was compatible with nine energetic materials. Besides, the compatibility results of the thermal analysis were confirmed by the XRD technique.

Differential scanning calorimetry and vacuum stability test as methods to determine explosives compatibility

During production, storage and manipulation of explosive materials it is important to be able to evaluate potential risks when they come in contact with each other or with other non explosives materials. For this reason various analytical and instrumental methods are being developed and implemented to study the chemical compatibility of explosives with other materials. In this research a possibility has been examined of application of thermal method-Differential Scanning Calorimetry (DSC) and Vacuum Stability Test (VST) as methods to determine the compatibility of often used explosive materials: Octogen (HMX), Pentrite (PETN) and Ammonium Perchlorate (AP) with also often used polymer materials: polyamide 12 (PA 12), Hydroxyl Terminated Polybutadiene (HTPB), fluoroelastomer (Viton A). Standard STANAG4147 was used as criteria to estimate the compatibility between the observed materials.

Preparation of insensitive composites based on penta erythritol tetra nitrate particles coated with carbon black- Triton X114 by a solvent/non-solvent process via Taguchi design optimization

One way to reduce sensitivity and also to add special properties to explosives is to perform coating that depends on either the coating agent type or the usage process. In this work, the insensitive composite of penta erythritol tetra nitrate (PETN) was prepared with carbon black (CB) and Triton X-114 (TX114) by a solvent/non-solvent method. Taguchi experimental design (orthogonal array, L9) with using the impact sensitivity (H50) as a response was applied for the process optimization. Effects of the CB mass fraction, solvent flowrate, surfactant type and surfactant concentration were evaluated and the results were quantified by the analysis of variance (ANOVA). The ANOVA analysis predicted that the best H50 was 67.4 ? 1.5 cm for the optimum synthesis conditions of 5.0 wt% CB, 1 mL min-1 flowrate, and TX114 as a surfactant at a concentration of 2.0x10-3 mol L-1. The experimentally determined value of H50 was 68.0 ? 0.5 cm, which is in good agreement with the predicted value. Finally, thermal analysis and vacuum stability test were applied to the synthesized composite indicating that CB and TX114 are thermally adaptable and chemically compatible with PETN.

The Chemical Compatibility and Adhesion of Energetic Materials with Several Polymers and Binders: An Experimental Study

The chemical compatibility and the adhesion of energetic materials and additive materials exert a strong influence on the sensitivity, safety and performance of a polymer-bonded explosive (PBX). In this study, the chemical compatibility of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), pentaerythritol tetranitrate (PETN) with several polymers were evaluated using the vacuum stability test (VST) and the differential scanning calorimetry (DSC); while the adhesion between RDX or PETN and each binder based on these polymers was determined through interfacial characteristics using contact angle measurement. The experimental results demonstrate that RDX and PETN are compatible with polystyrene (PS), nitrocellulose (NC) and fluoroelastomer (FKM) according to the STANAG 4147. Therefore the two polymers can be used as adhesives in PBX composition. Moreover, based on interfacial characteristics such as interfacial tension and work of adhesion, the adhesion between RDX and each binder was predicted to be better than that of PETN.

Thermal decomposition and shelf-life of PETN and PBX based on PETN using thermal methods

The kinetics of exothermic reactions are important in assessing the potential of materials and systems for thermal explosion. In this paper, the thermal behavior and decomposition kinetics of pentaerythritol tetranitrate (PETN) and polymer-bonded explosives (PBXs) based on PETN were investigated using Thermogravimetric analysis (TGA) and Vacuum Stability Test (VST) methods. The Arrhenius activation energies and pre-exponential factors were determined by the Ozawa and Kissinger methods. Based on the overall kinetic parameters of decomposition reactions, the shelf-life of PETN and PBXs based on PETN could be calculated and predicted.