Understanding and controlling the glass transition of HTPB oligomers

Dossi, Eleftheria; Earnshaw, Jacob; Ellison, Laurence; Santos, Gabriella Rabello dos; Cavaye, Hamish; Cleaver, Douglas J.

doi:10.1039/d1py00233c

Cited by 20 publications

(11 citation statements)

References 54 publications

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“…The transition in the slope value of the specific volume curve is indicative of the T g of the HTPB sample . Dossi et al , conducted experiments to measure the T g of commercially available HTPB, which was found to be 197 K. Our MD model yields 202 K, with a 3.0% difference compared with the experimental data. The density of commercial HTPB has been reported by Zhou et al to be 0.90 g/cm 3 at 300 K. Our model shows a density of 0.88 g/cm 3 , with a 3.3% difference.…”

Section: Computational Model and Methodsmentioning

confidence: 86%

“…During the polymerization process, the butadiene monomers can add to the growing chain through three different addition modes: 1,2-addition, 1,4-addition ( cis ), and 1,4-addition ( trans ) (refer to Figure a). The addition modes contribute to the final polymer structure and their ratios can affect the final properties of the polymer . In this research, the ratio of commercial HTPB-QL (1,2-vinyl/1,4- trans /1,4- cis = 0.18/0.60/0.22) was used to build our MD model .…”

Section: Computational Model and Methodsmentioning

confidence: 99%

“…The addition modes contribute to the final polymer structure and their ratios can affect the final properties of the polymer. 41 In this research, the ratio of commercial HTPB-QL (1,2-vinyl/ Figures 1c and 1d show the constructed MD models for the MSST and shock simulation, respectively. The MSST approach was originally introduced by Reed et al 44 as a multiscale MD technique that satisfies both shock Hugoniot and the Rayleigh line to compute Hugoniot data at a reduced computational cost.…”

Section: Construction Of Atomistic Htpb Modelsmentioning

confidence: 99%

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Impact Velocity and Temperature Effects on the Shock Wave Propagation and Spallation of Hydroxyl-Terminated Polybutadiene: A Molecular Dynamics Study

Liu,

He,

Xian

et al. 2023

ACS Appl. Polym. Mater.

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Hydroxyl-terminated polybutadiene (HTPB) is frequently employed as a key component of propellant binder in missiles or solid rockets. Understanding its shock response can help us to deepen our understanding of the shock response in its composites. Considering that missiles or solid rockets often need to operate in various temperature environments, investigating the shock wave propagation within the HTPB and its spallation behaviors under different temperatures and impact velocities is critical for understanding its failure modes. By employing large-scale molecular dynamics simulations, we provide a thorough analysis of the shock propagation and spallation strength of the HTPB under different initial temperatures and impact velocities. The quantification of the spallation strength is done by indirect methods based on the acoustic and modified acoustic assumptions and by the direct method that analyzes atomic stress in the spallation region. Our simulation results reveal that the spallation strength is associated with the impact velocity acting on the materials as well as the initial temperature. When the initial temperature is below the glass transition temperature, the spallation strength exhibits a monotonic decrease with increasing impact velocity. In contrast, such monotonicity is not observed above the glass transition temperature. Our findings furnish insights at the molecular level regarding the spallation processes in HTPB under varying impact loadings and temperature conditions, thereby facilitating the design of HTPB materials with enhanced resistance to impact loading.

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Section: Computational Model and Methodsmentioning

confidence: 86%

Section: Computational Model and Methodsmentioning

confidence: 99%

Section: Construction Of Atomistic Htpb Modelsmentioning

confidence: 99%

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Impact Velocity and Temperature Effects on the Shock Wave Propagation and Spallation of Hydroxyl-Terminated Polybutadiene: A Molecular Dynamics Study

Liu,

He,

Xian

et al. 2023

ACS Appl. Polym. Mater.

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“…Nonetheless, the unique compositions of each individual polymer has postulated macroscopic effects on the physical and mechanical properties of HTPB [16]. The glass transition temperature (T g ) of HTPB has been experimentally shown to vary over 70 °C depending on the isomer content ratios and has been attributed to the main-chain rotations intimately related to vinyl-1,2 content [17]. Furthermore, terminal OH structures and their involvement in cross-linking also have direct impacts on mechanical properties [16,18] and have recently been the subject of several molecular dynamics studies, including the aggregation of HTPB hydroxyl groups [1,19].…”

Section: Introductionmentioning

confidence: 99%

Structure and energetics of hydroxyl‐terminated polybutadiene via density functional theory

Buszek,

Moore,

Lonnecker

et al. 2023

Propellants Explo Pyrotec

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Hydroxyl‐terminated polybutadiene (HTPB) is a commonly used binding polymer in industry to produce polyurethanes. HTPB synthesis via allylic radical propagation leads to varied compositions and conformations that govern the bulk physical and mechanical properties of this polymer. While HTPB is incredibly well studied, its enthalpy of formation is still an open question and is critical to understanding the energetic contributions of the binding polymer in propellant formulations. This study investigates a series of HTPB polymers of experimentally relevant size and composition to understand the effects of conformations and monomer compositions on enthalpies of formation. The distribution of component monomer species comprising HTPB polymers is shown to have a significant effect on the condensed phase enthalpy of formation. The present study provides a best estimate of 331.2±50.3 kJ/mol or 150.7±22.9 kJ/kg for the condensed phase enthalpy of formation for commercially available HTPB formulations. The effects of the polymer folding motifs are smaller but distinct, with more highly folded structures exhibiting lower enthalpies of formation.

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“…It is well known that there are three different isomeric forms of HTPB: cis-1,4-; trans-1,4-; and 1,2-polybutadiene [ 18 ]. The different isomers have significantly different properties.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Comparative Study of Polyether-b-polybutadiene-b-polyether Triblock Copolymers for Use as Polyurethanes

Bi,

Zhu,

Han

et al. 2023

Polymers

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In this paper, the effects of HTPBs with different main-chain microstructures on their triblock copolymers and polyurethane properties were investigated. Three polyether-modified HTPB triblock copolymers were successfully synthesized via a cationic ring-opening copolymerization reaction using three HTPBs with different microstructures prepared via three different polymerization methods as the macromolecular chain transfer agents and tetrahydrofuran (THF) and propylene oxide (PO) as the copolymerization monomers. Finally, the corresponding polyurethane elastomers were prepared using the three triblock copolymers as soft segments and toluene diisocyanate (TDI) as hard segments. The results of an analysis of the triblock copolymers showed that the triblock copolymers had lower viscosity and glass transition temperature (Tg) values as the HTPB 1,2 structure content decreased, although the effect on the thermal decomposition temperature was not significant. An analysis of the polyurethane elastomers revealed that as the content of the 1,2 structure in HTPB increased, its corresponding polyurethane elastomers showed a gradual increase in breaking strength and a gradual decrease in elongation at break. In addition, PU-1 had stronger crystallization properties compared to PU-2 and PU-3. However, the differences in the microstructures of the HTPBs did not seem to have much effect on the surface properties of the polyurethane elastomers.

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Understanding and controlling the glass transition of HTPB oligomers

Abstract: In this paper, we use a combination of experiment and simulation to achieve enhanced levels of synthetic control on the microstructure of the much-used binder material hydroxyl terminated polybutadiene (HTPB)....

Cited by 20 publications

References 54 publications

Impact Velocity and Temperature Effects on the Shock Wave Propagation and Spallation of Hydroxyl-Terminated Polybutadiene: A Molecular Dynamics Study

Impact Velocity and Temperature Effects on the Shock Wave Propagation and Spallation of Hydroxyl-Terminated Polybutadiene: A Molecular Dynamics Study

Structure and energetics of hydroxyl‐terminated polybutadiene via density functional theory

Synthesis and Comparative Study of Polyether-b-polybutadiene-b-polyether Triblock Copolymers for Use as Polyurethanes

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