Molecular dynamics simulation of CL-20 based high temperature resistant PBX

Area of Science:

• Materials Science
• Computational Chemistry
• Energetic Materials

Background:

• Existing Deflagration to Detonation Transition (DDT) detonators face limitations due to output charges failing at high temperatures (200°C).
• There is a need to enhance the thermal resistance and overall performance of detonator charge materials.
• Hexanitrohexaazaisowurtzitane (CL-20) based polymer bonded explosives (PBXs) are investigated as a potential solution.

Purpose of the Study:

• To investigate CL-20 based PBXs as primary charge materials for high-temperature detonators.
• To evaluate the thermal resistance and performance of different PBX binders using molecular dynamics (MD) simulations.
• To identify the most suitable binder for CL-20 to withstand temperatures up to 200°C.

Main Methods:

• Molecular dynamics (MD) simulations were performed using Materials Studio software.
• Calculations included binding energies, trigger bond lengths, and mechanical properties for five PBX models.
• Simulations were conducted at various temperatures and crystal planes, employing the COMPASS force field over 1 ns.

Main Results:

• CL-20/F2602 exhibited the highest binding energy and shortest bond initiation length at ambient and elevated temperatures.
• CL-20/F2611 demonstrated superior thermal stability at high temperatures due to stronger hydrogen bonding.
• CL-20/PCTFE showed the best ductility, with CL-20/F2602 having the second-best ductility.

Conclusions:

• PBXs with F2602 binders offer excellent stability, compatibility, and satisfactory ductility for CL-20.
• PBXs with F2611 binders provide the best thermal stability, crucial for high-temperature applications.
• Both F2602 and F2611 are identified as suitable binders for CL-20 in advanced detonator designs.