Mechanical Characteristics and Thermal Decomposition Behavior of Polytetrahydrofuran Binder using Glycerol Propoxylate (M_n=260) as Crosslinking Agent

Abstract

Polytetrahydrofuran (PTHF) is an effective binder ingredient for improving propellant performance, even though it is not an energetic material. PTHF becomes sufficiently rubbery for use as a binder when a triol material such as glycerin is added as a crosslinking modifier. The cured PTHF/glycerin binder had unsatisfactory mechanical characteristics for use as a propellant binder, so a more appropriate crosslinking modifier than glycerin needs to be found. In this study, glycerol propoxylate (GPO), with a molecular weight of 260, was used as a crosslinking modifier, and the curing behavior, tensile properties, and thermal decomposition behaviors of the PTHF binder using GPO were investigated. The PTHF/GPO blend did not solidify when the PTHF/GPO mole ratio (ξ) was greater than a certain value. The PTHF (Mn=650)/GPO blend with ξ≤5 and the PTHF (Mn=1400)/GPO blend with ξ≤3 were used as propellant binders. From the curing behaviors and tensile properties, it was found that the PTHF/GPO binders ensured optimal mixing of the propellant ingredients and casting of the uncured propellant into the rocket motor case, and the tensile properties of the binders changed more drastically with the variation in ξ than did those of the PTHF/glycerin binders. The thermal decomposition behaviors of the PTHF/GPO binders were hardly dependent on ξ and were almost identical to those of the PTHF/glycerin binders.

Thermal Decomposition Behaviors and Burning Characteristics of Ammonium Nitrate/Polytetrahydrofuran/Glycerin-based Composite Propellants Supplemented with MnO2and Fe2O3

“…Furthermore, the burning rate of propellant D at 7 MPa was 1.7 mm s À1 . It was lower than that of the propellant with 8% ADC, 2.7 mm s À1 [3]. This is because that ADC acts not only a catalyst, but also an oxidizer.…”

“…As a result, the AN/PTHF/glycerin propellant did not ignite. The mechanical characteristics and the thermal decomposition behaviors of PTHF binders using glycerol propoxylate as a crosslinking agent have been investigated by Kohga [3]. However, their burning characteristics have not been reported yet.…”

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

“…PTHF does not solidify when IPDI is used alone [9], but did become sufficiently rubbery for use as a propellant binder upon the addition of GPO as a crosslinking modifier. GPO (Sigma-Aldrich) with a molecular weight of 1500 (GPO1) was used in this study, while GPO with a molecular weight of 260 (GPO2) was used in our previous study [14].…”

“…A cured PTHF/GPO blend would have good rubber-like elasticity because GPO does not have a linear structure. In a previous study [14], the use of a PTHF binder with GPO (M n = 260) as a crosslinking agent ensured optimal mixing of the propellant ingredients and casting of the uncured propellant into a rocket motor case, and these binders showed more flexible mechanical properties compared to those of PTHF/glycerin binders. GPO is produced in several different molecular weights.…”

“…The viscoelastic and thermal decomposition behaviors of PTHF/GPO blends depend on the molecular weight of GPO. GPO with a molecular weight of 260 was used in our previous study [14]. In this study, the curing behavior, tensile properties, and thermal decomposition behaviors of a PTHF binder with GPO with a molecular weight of 1500 were investigated, and the properties of this binder were compared with those of PTHF/GPO (M n = 260) binders.…”