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Modification of the Physical and Thermal Properties of Glycidyl Azide Polymer Through the Formation of a Star-Shaped Polymer

Bodaghi Asghar

Central European Journal of Energetic Materials

2022

Vol. 19, no. 3

248--263

Glycidyl azide polymer (GAP) is one of the most important binders in the preparation of propellants. One of the most important problems with this binder is its high glass transition temperature. In the present study, the physical and thermal properties of GAP were modified by the synthesis of a star shaped polymer. Dibromo end-functionalized two-arm polycaprolactone (PCL), (PCL)2-(Br)2, was synthesized by ring-opening polymerization (ROP) of ε-caprolactone monomer using 2,2-bis(bromomethyl)-1,3-propane diol as the initiator and stannous 2-ethylhexanoate as the catalyst. The bromines of the polymer were then replaced by azide groups by reaction with sodium azide (NaN3). The (PCL)2-(Br)2 was reacted with propargyl terminated polyepichlorohydrin (PTPECH) via a click reaction. Finally, (PCL)2-(PTPECH)2 was converted into (PCL)2-(GAP)2 by reaction with NaN3. 1H NMR, FT-IR and GPC studies revealed that (PCL)2-(GAP)2 was obtained. The thermal behaviour of this star polymer was investigated by thermogravimetric analysis (TGA) and derivative thermogravimetry. The results showed that (PCL)2-(GAP)2 decomposed in two stages. The first stage is related to degradation of the azide groups and the second stage was attributed to degradation of the PCL groups.