A New Approach for Synthesis of Low‐moisture Glycidyl Azide Polymer

Abstract

In this work, low‐moisture glycidyl azide polymer (GAP) was successfully prepared using a modified two‐step method. The modified method resembles the structure of the classical two‐step method, which is widely used to prepare the GAP. Firstly, epichlorohydrin (ECH) is polymerized into polyepicholorohydrin (PECH), which is subjected afterward to azidation step using sodium azide (NaN3). Interestingly, minimizing the water content in the final GAP product, which is a challenging when dealing with GAP as a rocket propellant binder, was effectively achieved by utilizing low boiling point solvents instead of the relatively high boiling point Dimethyl formamide (DMF), monitoring the volatility of ECH and controlling the exothermicity of the reaction. Prepared GAP samples were investigated using Fourier transformer infra‐red (FT‐IR), gel‐permeation chromatography (GPC) and elemental analysis apparatus (CHNS) were used to characterize the product. The moisture % in the final product was examined using the Karl‐Fisher Technique. Results showed the successful preparation of GAP with low water content (<0.01 %), high average molecular weight (> 2000 g·mol–1), 42.82 % nitrogen, a viscosity of 3484 cP at 20 °C, yield ranges between 95–98 % and a polydispersity index of 1.2. The prepared GAP is promising for replacement of the classical GAPs in the energetic materials applications.

Synthesis and Characterization of a Novel Aqueous Glycidyl Azide Polymer Emulsion

“…The results showed that the addition of the variety of prepolymers improved the mechanical brittleness of GAP-based elastomers. Abdelhafiz and Elbeih 14 successfully prepared a low-moisture GAP using a modified two-step method, where epichlorohydrin was polymerized into polyepichlorohydrin and subjected afterward to the azidation step using sodium azide. Besides, it is also reported that the linear GAP can be modified to the branched GAP with a lower viscosity than that of the linear GAP, which was then cross-linked with the curing agent to prepare thermosetting energetic elastomers.…”

Influence of different crosslinking mixtures on the mechanical properties of composite solid rocket propellants based on HTPB

“…27,28 Low molecular weight triols such as TMP and triethanolamine were used as crosslinkers in different types of research. 29 –35 The most significant key parameter for binder system is the CLD which defined as moles of elastically effective matrix chains per unit volume. In addition to CLD, there are other parameters which determine the mechanical and physical properties of the binder such as network configuration, micro inhomogeneity, and polymer chains chemical nature.…”