Evaluation of the 3‐hydroxy pyridine antioxidant effect on the thermal‐oxidative degradation of HTPB

Abstract

The effect of the mixture of two antioxidants has been evaluated on the thermal‐oxidant degradation of the hydroxyl‐terminated polybutadiene (HTPB) because of its importance in the coatings and adhesives industries. 2,2‐Methylene bis(4‐methyl‐6‐tertiarybutylphenol) or A.O.2246 and 3‐hydroxy pyridine have been considered as antioxidants in this study as a common HTPB antioxidant and an active antioxidant, respectively. The thermal‐oxidant degradation behavior of the HTPB has been investigated in the presence of a mixture of two antioxidants by TGA and DTG tests, and, subsequently, the results of these tests have been interpreted by two model‐free methods, e.g., Kissinger–Akahira–Sunose and Friedman methods. The results revealed that the mixture of two antioxidants affected the activation energy of the thermal‐oxidant degradation reaction of the HTPB. The calculated activation energy value obtained from the Kissinger–Akahira–Sunose method was about 199 ± 1 kJ⋅mol−1. In addition, the Ea value at various conversion rates has also been calculated by using the Friedman method. This method showed that the highest Ea value in the thermal‐oxidant degradation reaction belonged to the initiation step of the reaction (about 299 kJ⋅mol−1). Moreover, the lowest activation energy value was correlated to the second step of the degradation reaction at a conversion rate of 0.6 (about 184 kJ⋅mol−1).

The kinetics and mechanism of polymer‐based NHC‐Pd‐pyridine catalyzed heterogeneous Suzuki reaction in aqueous media

“…The Arrhenius equation can be linearized as follows: where A is a frequency factor, E a is activation energy for the reaction (J/mol), R is the universal gas constant (J/(mol⋅K)), and T is the temperature in kelvins (K) . Activation energy can be calculated graphically by plotting ln( k ) as a function of 1/ T according to Equation .…”

“…where A is a frequency factor, E a is activation energy for the reaction (J/mol), R is the universal gas constant (J/(mol⋅K)), and T is the temperature in kelvins (K). 46,47 Activation energy can be calculated graphically by plotting ln(k) as a function of 1/T according to Equation (8). The graph of the ln(k 3 ) versus 1/T is shown in Figure 12.…”

Bioinspired modified graphene oxide/polyurethane composites with rapid self-healing performance and excellent mechanical properties

“…1,2 Hydroxyl-terminated polybutadiene (HTPB)-based PU is one of the promising materials for composite solid propellant binders and protective coating [3][4][5] owing to its outstanding elasticity, toughness and water-resistance, as well as sub-ambient glass transition temperature (T g ). [6][7][8][9][10] However, as a kind of conventional thermosetting polymeric material with irreversible crosslinking, it cannot be repaired, once damaged.…”

Hyperbranched polyamide modified graphene oxide-reinforced polyurethane nanocomposites with enhanced mechanical properties

“…HTPB-based polyurethane (PU) is an important kind of polymeric material that has been widely applied in numerous areas, such as adhesives, coatings, and composite solidpropellants. [3][4][5][6] Owing to its outstanding elasticity, toughness, and chemical resistance, and its sub-ambient glass transition temperature (T g ), 3,[7][8][9][10][11] HTPB-based PU has been regarded as one of the most suitable binders for composite solid-propellants. 12 It connects the oxidant and other fuel additives dispersed in composite solid-propellants via forming a PU network upon reacting with diisocyanate.…”