Changes in the Mechanical Properties of Energetic Materials With Aging

The paper deals with the competing models of internal surfaces heating of gunpowder elements channels in a liquid under impact compression. The first model is based on impact volume compression of the air in the channels at impact, and the second model is based on the action of shear stresses arising due to viscous friction of a liquid flowing in the channels under the influence of external pressure. The paper presents experimental data on the character of ignition site in the channels based on the assessment of artillery pyroxylin powder 12/7 sensitivity equivalent to the impact drop-hammer.

Section: Introductionmentioning

confidence: 99%

Impact Initiated Combustion of Channel Gunpowder in Liquid

Ganigin

Demoretsky

Samarin

et al. 2020

“…The mechanical properties of composite energetic materials, such as explosives and solid rocket motor propellants, change with time, ap rocess known as aging [1][2][3][4][5][6][7][8][9][10][11][12][13][14].A ging is usually the result of chemical (e.g. cross-linking) and physical (e.g.…”

Section: Iintroductionmentioning

confidence: 99%

Active Sensing for Monitoring the Properties of Solid Rocket Motor Propellant Grains

Lopatin¹,

Grinstein²

2015

Aging induced changes in the mechanical properties of solid propellant can lead to defects, such as cracks and grain‐liner separations, that limit the service lifetime of solid rocket motors. The use of embedded sensors is one approach that is being explored by various researchers to augment legacy inspection and prediction methods. We present herein an active sensing technique that is particularly suited for monitoring the properties of solid propellant, as it does not introduce electrical wires into the motor. Based on the use of magnetic induction for excitation and an optical fiber Bragg grating sensor to measure deformation, the method can be used to characterize the properties of a material with which it is in contact. In this paper, we first present proof‐of‐principal experiments demonstrating the utility of the method in characterizing the visco‐elastic properties of an adhesive, and in following changes in viscosity of an epoxy resin during cure. We next apply the method to solid propellant, and present data demonstrating that the method can be used to measure a deflection‐load curve of an aluminized HTPB propellant. In addition, we also show that the observed strain rate sensitivity matches that found in the literature and that the method had more than adequate resolution to observe the expected changes in material properties due to aging.

Synthesis and Characterization of New PGN Based Reactive Oligomeric Plasticizers for Glycidyl Azide Polymer

Bodaghi

Shahidzadeh

2018

New heterobifunctional oligomeric energetic plasticizer with alkyne at one end and a hydroxyl group at the other end, was synthesized via ring opening polymerization of glycidyl nitrate monomer, propargyl alcohol as initiator and BF3 as a catalyst. The terminal hydroxyl group of plasticizer capped with methoxy and acetyl groups to generate two other types of reactive plasticizer. The chemical structure of plasticizers has characterized by FT‐IR and 1H NMR spectroscopy as well as DSC, and TGA methods. Also, plasticizers reactivity toward alkyne‐azide reaction, have evaluated through LUMO energy level calculation of reactive plasticizer that containing one and two repeating units in their structure. Moreover, the results show that grafting up to 10 % of the total amount of azide groups of GAP, reduces the viscosity and the glass transition temperature of GAP‐g‐PGN copolymer in comparison to glycidyl azide polymer.