scholarly journals Surface Coating of Cyclotetramethylenetetranitramine (HMX) Particles and Its Property Investigation

2021 ◽  
Vol 8 ◽  
pp. 77-81
Author(s):  
Guo Yan ◽  
Shi Xiaobing ◽  
Pang Weiqiang ◽  
Qin Zhao ◽  
Xu Huixiang ◽  
...  
Keyword(s):  
Water Solution ◽  
Thermoplastic Polyurethane ◽  
Impact Sensitivity ◽  
Coating Materials ◽  
Internal Solution ◽  
Wetting Ability ◽  
Electron Spectrometry ◽  
Friction Sensitivity ◽  
The Impact

To improve the safety of cyclotetramethylenetetranitramine (HMX) particles, the polymer thermoplastic polyurethane elastomer (TPU) and nitrocellulose (NC) were introduced to coat HMX powder by water-solution suspension method and internal solution method, respectively. Scanning electron microscope (SEM) and X-ray photo-electron spectrometry (XPS) were employed to characterize the HMX samples and the role of NC and TPU in the coating processes were discussed. The impact sensitivity, friction sensitivity, and the thermal decomposition of coated HMX particles were investigated, and compared to the unprocessed ones. The results indicate that both TPU and NC can improve the wetting ability of the coating materials on HMX surface and reinforce the connection between HMX and the coating materials. The impact sensitivity and friction sensitivity of HMX samples decrease obviously after they have been surface coated; the drop height (H50) is increased from 35.24 cm to 50.08 cm, and the friction probability is reduced from 93.2 % to 58.3%. The activation energy (Ea) and the self-ignition temperature increase by 10.46 KJ·mol-1 and 1.8, respectively.

scholarly journals Effect of Nano-Sized Energetic Materials (nEMs) on the Performance of Solid Propellants: A Review

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 133
Author(s):  
Weiqiang Pang ◽  
Chongqing Deng ◽  
Huan Li ◽  
Luigi T. DeLuca ◽  
Dihua Ouyang ◽  
...  
Keyword(s):  
Energetic Materials ◽  
Research Topic ◽  
Impact Sensitivity ◽  
Solid Propellants ◽  
Rocket Nozzle ◽  
Nano Scale ◽  
Different Types ◽  
Solid Rocket ◽  
Friction Sensitivity ◽  
The Impact

As a hot research topic, nano-scale energetic materials have recently attracted much attention in the fields of propellants and explosives. The preparation of different types of nano-sized energetic materials were carried out, and the effects of nano-sized energetic materials (nEMs) on the properties of solid propellants and explosives were investigated and compared with those of micro-sized ones, placing emphasis on the investigation of the hazardous properties, which could be useable for solid rocket nozzle motor applications. It was found that the nano-sized energetic materials can decrease the impact sensitivity and friction sensitivity of solid propellants and explosives compared with the corresponding micro-sized ones, and the mechanical sensitivities are lower than that of micro-sized particles formulation. Seventy-nine references were enclosed.

scholarly journals Biofilms and сhronic rhinosinusitis

2020 ◽  
pp. 59-65
Author(s):  
V. V. Shilenkova
Keyword(s):  
Sea Water ◽  
Water Solution ◽  
Immune Defense ◽  
Upper Respiratory Tract ◽  
Chronic Infections ◽  
Mechanical Destruction ◽  
Nasal Irrigation ◽  
Upper Respiratory ◽  
The Impact

Introduction. A biofilm is a community of bacteria embedded in a matrix consisting of polysaccharides, nucleic acids, and proteins. Biofilms are resistant to antibiotics, antiseptics, and immune defense factors of the human body. Currently, the role of bacterial biofilms in the pathogenesis of chronic infections is known. There are a lot of articles confirming the detection of biofilms in diseases of the upper respiratory tract and ear: adenoiditis, recurrent and chronic otitis, laryngitis.Biofilms and Chronic Rhinosinusitis (CRS). Biofilms can play a significant role in prolonging inflammation in the paranasal sinuses. Biofilms are found in 76.7% of patients with CRS. This fact can serve as one of the explanations for the refractoriness of drug therapy and recurrent inflammations after surgical treatment.Methods for Controlling Biofilms. Is there a Way Out? As part of the strategy of removing biofilm, it is important to destroy its structure to planktonic forms, which will allow for the process of managing CRS progress. Antibiotic therapy alone is considered insufficient. Nasal irrigation can provide a violation of the biofilm integrity due to the mechanical destruction of its matrix and have a significant impact on the outcome of the disease. The nasal irrigation preparation containing isotonic sea water solution added with carbon dioxide (CO2-0.4%) has such an effect. In an experimental study, it was shown that 98% of the bacteria were non-viable when processing Staphylococus aureus biofilm.Conclusion. The impact on biofilms should be complex, including medication, physical means, irrigation of the nasal cavity.

Impact Sensitivity of RDX and Viton Compositions Prepared by Co-precipitation Method

2015 ◽  
Vol 65 (4) ◽  
pp. 287 ◽  
Author(s):  
P. B. Wagh ◽  
S. V. Ingale ◽  
Ratanesh Kumar ◽  
R.H. Naina ◽  
T. C. Kaushik ◽  
...  
Keyword(s):  
Linear Trend ◽  
Impact Sensitivity ◽  
Precipitation Method ◽  
Wide Range ◽  
Homogeneous Composition ◽  
Sensitivity Data ◽  
Spectroscopy Studies ◽  
Co Precipitation ◽  
Friction Sensitivity ◽  
The Impact

<p>Desensitisation of explosive materials using polymers is an important area in safe utilisation of explosives in various applications. The RDX/viton composition has been developed using co-precipitation method with varying content of viton, ranging from 5 to 35 wt per cent. RDX and viton were dissolved in acetone which is a common solvent for RDX and viton, and then the acetone was extracted from the solution by distillation resulting in homogeneous RDX/viton composition. Infrared spectroscopy studies indicated presence of RDX and viton in the resulting compositions. Thermogravimetric and differential thermal analysis studies made on yielded compositions confirmed that RDX is present in the composition in desired content. The shift in exotherm of RDX/viton composition as compared to RDX showed that polymer-bonded RDX compositions are more stable. The impact sensitivity studies showed that sensitivity of RDX/viton composition decreased with increasing content of viton. The similar trend was observed for friction sensitivity. The co-precipitation method has been found to be advantages to obtain homogeneous composition of RDX and viton (with viton content up to 25 wt per cent) as revealed by linear trend in sensitivity data measurements. It has been demonstrated that the sensitivity of RDX can be tailored within a wide range using viton so as to suit in desired applications.</p><p><strong>Defence Science Journal, Vol. 65, No. 4, July 2015, pp. 287-291, DOI: http://dx.doi.org/10.14429/dsj.65.8647</strong></p>

scholarly journals Influence of Different Polymeric Matrices on the Properties of Pentaerythritol Tetranitrate

2021 ◽  
Vol 71 (2) ◽  
pp. 177-184
Author(s):  
Ahmed Elbeih ◽  
Mahmoud Abdelhafiz ◽  
Ahmed K. Hussein
Keyword(s):  
Impact Sensitivity ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Pentaerythritol Tetranitrate ◽  
Polymeric Matrices ◽  
Velocity Of Detonation ◽  
Polymer Bonded Explosives ◽  
Friction Sensitivity ◽  
Styrene Butadiene ◽  
The Impact

Six different polymeric matrices were fabricated to reduce the sensitivity of PETN (Pentaerythritol tetranitrate). The polymeric matrices used were individually based on Acrylonitrile butadiene rubber (NBR) softened by plasticizer, styrene-butadiene rubber (SBR) softened by oil, polymethyl methacrylate (PMMA) plasticised by dioctyl adipate (DOA), polydimethylsiloxane (PDMS), polyurethane matrix, and Fluorel binder. A computerised plastograph mixer was utilised for producing three polymer-bonded explosives (PETN-NBR, PETN-SBR, and PETN-PDMS) based on the non-aqueous method. A cast-cured method was used to prepare PBX based on polyurethane (PETN-HTPB), while the slurry technique was used to prepare beads of PETN coated by either fluorel binder (PETN-FL) or based on PMMA forming (PETN-PMMA). The heat of combustion and sensitivities were investigated. The velocity of detonation was measured, while the characteristics of the detonation wave were deduced theoretically by the EXPLO 5 (thermodynamic code). The ballistic mortar experiment was performed to determine the explosive strength. By comparing the results, it was found that PDMS has the highest influence on decreasing the impact sensitivity of PETN, while the cast cured PETN-HTPB has the lowest friction sensitivity. On the other side, PETN-FL has the highest detonation parameters with high impact sensitivity. Several relationships were verified and the matching between the measured results with the calculated ones was confirmed.

Intergroup Threat and Outgroup Attitudes

2013 ◽  
Vol 44 (5) ◽  
pp. 311-319 ◽  
Author(s):  
Marco Brambilla ◽  
David A. Butz
Keyword(s):  
Gay Men ◽  
Social Group ◽  
Welfare Recipients ◽  
Intergroup Attitudes ◽  
Social Policies ◽  
Intergroup Threat ◽  
Economic Threat ◽  
The Impact ◽  
General Climate

Two studies examined the impact of macrolevel symbolic threat on intergroup attitudes. In Study 1 (N = 71), participants exposed to a macrosymbolic threat (vs. nonsymbolic threat and neutral topic) reported less support toward social policies concerning gay men, an outgroup whose stereotypes implies a threat to values, but not toward welfare recipients, a social group whose stereotypes do not imply a threat to values. Study 2 (N = 78) showed that, whereas macrolevel symbolic threat led to less favorable attitudes toward gay men, macroeconomic threat led to less favorable attitudes toward Asians, an outgroup whose stereotypes imply an economic threat. These findings are discussed in terms of their implications for understanding the role of a general climate of threat in shaping intergroup attitudes.

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