Structure and mechanical properties of novel composites based on glycidyl azide polymer and propargyl-terminated polybutadiene as potential binder of solid propellant

Fluoropolymer/Glycidyl Azide Polymer (GAP) Block Copolyurethane as New Energetic Binders: Synthesis, Mechanical Properties, and Thermal Performance

In order to enhance the application performance of glycidyl azide polymer (GAP) in solid propellant, an energetic copolyurethane binder, (poly[3,3-bis(2,2,2-trifluoro-ethoxymethyl)oxetane] glycol-block-glycidylazide polymer (PBFMO-b-GAP) was synthesized using poly[3,3-bis(2,2,2-trifluoro-ethoxymethyl)oxetane] glycol (PBFMO), which was prepared from cationic polymerization with GAP as the raw material and toluene diisocyanate (TDI) as the coupling agent via a prepolymer process. The molecular structure of copolyurethanes was confirmed by attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR-FTIR), nuclear magnetic resonance spectrometry (NMR), and gel permeation chromatography (GPC). The impact sensitivity, mechanical performance, and thermal behavior of PBFMO-b-GAP were studied by drop weight test, X-ray photoelectron spectroscopic (XPS), tensile test, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA), respectively. The results demonstrated that the introduction of fluoropolymers could evidently reduce the sensitivity of GAP-based polyurethane and enhance its mechanical behavior (the tensile strength up to 5.75 MPa with a breaking elongation of 1660%). Besides, PBFMO-b-GAP exhibited excellent resistance to thermal decomposition up to 200 °C and good compatibility with Al and cyclotetramethylene tetranitramine (HMX). The thermal performance of the PBFMO-b-GAP/Al complex was investigated by a cook-off test, and the results indicated that the complex has specific reaction energy. Therefore, PBFMO-b-GAP may serve as a promising energetic binder for future propellant formulations.

Glycidyl Azide Polymer and its Derivatives-Versatile Binders for Explosives and Pyrotechnics: Tutorial Review of Recent Progress

Glycidyl azide polymer (GAP), an energetic binder, is the focus of this review. We briefly introduce the key properties of this well-known polymer, the difference between energetic and non-energetic binders in propellant and explosive formulations, the fundamentals for producing GAP and its copolymers, as well as for curing GAP using different types of curing agents. We use recent works as examples to illustrate the general approaches to curing GAP and its derivatives, while indicating a number of recently investigated curing agents. Next, we demonstrate that the properties of GAP can be modified either through internal (structural) alterations or through the introduction of external (plasticizers) additives and provide a summary of recent progress in this area, tying it in with studies on the properties of such modifications of GAP. Further on, we discuss relevant works dedicated to the applications of GAP as a binder for propellants and plastic-bonded explosives. Lastly, we indicate other, emerging applications of GAP and provide a summary of its mechanical and energetic properties.

Study on Interaction between Propargyl-Terminated Polybutadiene and Plasticizers Based on Simulation and Experiments

Molecular dynamics (MD) simulation and experimental methods are used to explore the interaction between the propargyl-terminated polybutadiene (PTPB) binder and plasticizers bis(2,2-dinitropropyl) formal/acetal (BDNPF/A) and dioctyl sebacate (DOS). Flory-Huggins parameters, radial distribution functions, and binding energies between PTPB and plasticizers are calculated using MD simulations. The solubility parameters of PTPB and the plasticizers are calculated by both MD and group contribution method. The mesoscopic dynamics (MesoDyn) is used to simulate the meso-morphology of PTPB and plasticizer blends by converting the results of MD simulation into MesoDyn simulation parameters. The results of simulations and calculations show that PTPB has better compatibility with DOS than with BDNPF/A, and DOS is more suitable as a plasticizer for PTPB. The results of dynamic rheological experiments show that BDNPF/A has little effect on the dynamic viscosity of PTPB, and DOS can significantly reduce the dynamic viscosity of PTPB and has better plasticizing effect on PTPB. Differential scanning calorimetry and dynamic mechanical analysis tests indicate that the DOS and PTPB blend has only one glass transition temperature, while the PTPB and BDNPF/A blend has two glass transition temperatures. Both simulations and experimental results show that the PTPB binder have better compatibility with DOS than with BDNPF/A, and DOS has better plasticization effects on the PTPB binder.

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

Current solid rocket propellant formulations still employ traditional ingredients utilized since the 1960s, such as hydroxyl terminated polybutadiene (HTPB). Recent advances in energetic polymer see many binders capable of providing higher specific impulse and burn rates over HTPB. As shown by calculations, even slight increases in specific impulse can drastically increase the maximum payload of a launch system. Therefore, replacing HTPB with energetic binders could provide heavy space missions the needed extra boost. Energetic binders could also be paired with chlorine-free energetic oxidizers to synergistically provide a specific impulse exceedingly higher than the current formulation while reducing pollution. A comprehensive evaluation of the synthesis, mechanical properties, and performance of various trending and overlooked energetic polymers is described. Several outstanding candidates show promising properties to replace HTPB.

Synthesis and properties of a novel highly thermal stable N-propargyl monomer containing benzoxazole ring

A novel highly thermal stable propargyl functional compound containing benzoxazole ring, N, N, N′, N′-tetra propargyl-5-amino-2-(p-aminophenyl) benzoxazole (TPAPB), was proposed and synthesized using a phase-transfer catalytic method. The cure behavior of TPAPB was investigated by non-isothermal differential scanning calorimetry analysis. The solubility and rheological properties of TPAPB, as well as its broad temperature window from 130°C to 200°C with low viscosity, offered excellent processability for TPAPB to be used as a potential monomer of thermosetting polymer resin. It was found that the glass transition temperature of cured TPAPB was 359°C, and the temperature of 5% weight loss was 418°C in argon with the char residue up to 70% at 700°C. The polymerized resin exhibited high heat resistance and thermal stability, together with its processability, making it good candidate as highly heat-resistant polymer matrix for advanced composite applications.