Thermal decomposition and kinetics studies on 1,4-dinitropiperazine (DNP)

Area of Science:

• Chemical Engineering
• Materials Science
• Physical Chemistry

Background:

• 2,4-dinitroanisole (DNP) is a nitramine compound requiring detailed study of its thermal decomposition.
• Understanding thermal decomposition is crucial for safety and predicting material behavior under heat.

Purpose of the Study:

• To elucidate the kinetics and mechanism of DNP's thermal decomposition.
• To determine key kinetic parameters like activation energy and pre-exponential factor.
• To identify the primary gaseous products and initial bond cleavage during thermolysis.

Main Methods:

• Thermogravimetry (TG)
• Differential Thermal Analysis (DTA)
• Infrared (IR) Spectroscopy
• Differential Scanning Calorimetry (DSC)
• Time-resolved Fourier-transform infrared spectroscopy (T/Jump FT-IR)
• Flynn-Wall-Ozawa method for activation energy determination

Main Results:

• The solid-state decomposition followed a nucleation and growth model (Avramie Erofeev function, n=1).
• Activation energy (Ea) was determined to be 116.51 kJ/mol, with a pre-exponential factor (A) of 10(10.52) s(-1).
• T/Jump FT-IR analysis indicated CH2O, NO2, and NO as major decomposition products over CO2 and HCN, suggesting N-N and C-N bond cleavage as the initial step.

Conclusions:

• The thermal decomposition of DNP is governed by a nucleation and growth mechanism.
• The kinetic parameters and product analysis provide insight into the decomposition pathway.
• Initial bond scission involves the N-N and C-N bonds, leading to the observed products.