Mechanical Characteristics and Thermal Decomposition Behaviors of Polytetrahydrofuran Binder with Glycerol Propoxylate (M_n=1500) as a Crosslinking Agent

Abstract

Polytetrahydrofuran (PTHF) is an effective binder ingredient for improving propellant performance, although it is not an energetic material. PTHF becomes sufficiently rubbery for use as a binder when a triol is added as a crosslinking modifier. In this study, glycerol propoxylate (GPO), with a molecular weight of 1500, was used as a crosslinking modifier, and the curing behavior, tensile properties, and thermal decomposition behaviors of the PTHF binder with GPO were investigated. A PTHF (M n = 650)/GPO blend with a PTHF/GPO mole ratio (x) less than or equal to 4 and a PTHF (M n = 1400)/GPO blend with x 1 were used as propellant binders. The curing behaviors and mechanical properties of the PTHF/GPO blends were influenced by the molecular weight of PTHF and x, while the thermal decomposition behaviors were not affected. It was found that the PTHF/GPO blends had higher initial viscosity, longer pot life, and unique mechanical properties compared to those of the PTHF blends supplemented with GPO (M n = 260).Keywords: Propellant binder · Polytetrahydrofuran · Glycerol propoxylate · Mechanical behavior · Thermal decomposition behavior [a] M. Kohga

Mechanical Properties and Thermal Decomposition Behaviors of Hydroxyl‐Terminated Polybutadiene/Glycerol Propoxylate Blend and Its Application to Ammonium Nitrate‐Based Propellants

“…The network density of a cross‐linked polymer was estimated by the degree of swelling by an appropriate solvent at equilibrium. A swelling test was conducted using a rectangular parallelepiped sample (20 mm×20 mm×2 mm) at 298 K. Toluene was used as the swelling solvent [12–15]. The mass of the sample was measured before and after immersion in toluene, and the volumes were calculated.…”

“…In other studies, glycerol propoxylate (GPO) was used as a crosslinking modifier (see Figure 1 for chemical structure) for the PTHF binder [14, 15]. GPO is a triol material with a zigzag structure, and it has one oxygen atom in a repeating unit.…”

Review of novel energetic polymers and binders – high energy propellant ingredients for the new space race

“…Polytetrahydrofuran (PTHF) based propellant produce promising mechanical properties while having better oxygen balance and higher burn rate than HTPB [57][58][59][60]. In fact, in a propellant of 80% ammonium perchlorate to 20% binder by weight mixture, directly replacing HTPB with PTHF results in a 10-second increase in specific impulse.…”

“…Although PTHF does not contain any energetic components, it gives a specific impulse comparable to that of energetic polymers due to its higher oxygen balance than HTPB [58][59][60]. Kohga and his team have been testing various formulations of PTHF and has shown that certain ammonium perchlorate-PTHF-based formulation has nearly twice the burn rate of HTPB-based propellant [57].…”

“…The same team also performed various testing of the mechanical properties of PTHF and GPO-based formulations with successful results. It was found that PTHFbased formulations have exceptional mechanical properties that are higher than that of GAP-based formulations [58][59][60].…”