Synthesis and kinetic study on the thermal degradation of triblock copolymer of polycaprolactone‐poly (glycidyl nitrate)‐polycaprolactone (PCL‐PGN‐PCL) as an energetic binder

Abstract

In this study, an energetic binder is synthesized via ring opening copolymerization of ε‐caprolactone with poly (glycidyl nitrate) (PGN) of low molecular weight (Mn = 1350 g mol−1) as a macroinitiator to form triblock copolymer polycaprolactone‐PGN‐polycaprolactone (PCL‐PGN‐PCL) (Mn = 4128 g mol−1). The effects of catalyst type and its concentration, reaction time, and solvent are investigated in this polymerization reaction. The resulting triblock copolymer is characterized by Fourier transform infrared spectroscopy (FT‐IR), nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The DSC result shows that the glass transition temperature of triblock copolymer (Tg = −50°C) is lower than PGN (Tg = −35°C). Also, the decomposition kinetics of this energetic binder is studied by DSC, TGA, and its derivative (DTG). An advanced isoconversional method is applied for kinetic analysis. Activation energy is calculated by Flynn‐Wall‐Ozawa (FWO) and Kissinger methods. The resulting activation energy from Kissinger method for the first and the second steps are 42.98 and 74.56 kJ mol−1, respectively. Also, it is found from FWO results that the activation energy for the copolymer increases with degradation degree (α).

Review on energetic copolymer binders for propulsion applications: Synthesis and properties

“…This review article has provided a comprehensive overview of the F I G U R E 2 2 Synthesis process of PCL/PGN/PCL copolymer. 107 F I G U R E 2 3 Glass transition temperature of PGN and PCL/PGN/PCL Copolymer determined by DSC analysis. 107 different types of copolymers and their properties, as well as the current challenges and opportunities in the field.…”

“…Abrishami et al 107 synthesized an innovative energetic binder called PCL-PGN-PCL copolymer, utilizing stannous octoate catalyst and PGN macromolecules. With approximately 70% PCL content, this copolymer exhibited a lower glass transition temperature of À50 C in comparison to PGN's À35 C. The thermal analysis results demonstrated exothermic decomposition of the copolymer at temperatures ranging from 198 to 201 C in the first stage, and from 335 to 360 C in the second stage, which varied with the heating rate.…”

Study on curing kinetics and behaviours of PGN adhesives

“…Polyglycidyl nitrate (PGN) is an energetic binder with -ONO 2 groups. Due to its high energy density and high oxygen content, [1][2][3][4][5] it is regarded as one of the most potential energetic adhesives in solid propellants in the future. PGN has been synthesized in the last century, so there are some reports on its synthesis, 6,7 modication 8,9 and application, [10][11][12] but studies on the reaction kinetics of the PGN curing reaction system have been rare.…”

“…Due to its high energy density and high oxygen content, [1][2][3][4][5] it is regarded as one of the most potential energetic adhesives in solid propellants in the future. PGN has been synthesized in the last century, so there are some reports on its synthesis, 6,7 modication 8,9 and application, [10][11][12] but studies on the reaction kinetics of the PGN curing reaction system have been rare. It is important that curing kinetics and behaviours as well as the entire curing process of the system have potential values for improving its curing stability.…”

Studies on PBFMO-b-PNMMO alternative block thermoplastic elastomers as potential binders for solid propellants

“…4,5 Among the energetic binders, azide functional polymers (viz., glycidyl azide polymer (GAP), poly(3,3-bis(3azido methyl)oxetane) (PBAMO), poly((3-azido methyl)-3methyl oxetane) (PAMMO)) and nitrato polyethers (viz., poly((3-nitrato methyl)-3-methyl oxetane) (PNMMO), and poly(glycidyl nitrate) PGN) have received widespread attention in recent decades. [6][7][8] In the past three decades, uoropolymers have been extensively studied in propellant or plastic-bonded explosive (PBX) formulations. [9][10][11] This is due to their high density, long-term chemical stability, low coefficients of friction, and compatibility with energetic materials, especially strong oxidative ability with metals.…”