Curing Reaction Kinetics of the EHTPB-Based PBX Binder System and Its Mechanical Properties

Zhang, Xing; Liu, Yucun; Chai, Tianyou; Ma, Zhongliang; Jia, Kanghui

doi:10.3390/coatings10121266

Cited by 8 publications

(10 citation statements)

References 28 publications

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“…The reaction rate of IPDI was slightly faster than that of TDI. This finding is similar to the kinetic investigation by Zhang et al and Kamran et al [ 29 , 31 ] in separate research. The reactivity of isocyanate groups in TDI was more stable than that in IPDI because of the resonance between CH 2 groups in the aromatic benzene structure [ 50 , 51 ].…”

Section: Resultssupporting

confidence: 93%

“…The reactions were expressed in Equations (1) and (2). The isocyanate groups (B) also reacted with a nitro group (F) in hexogen to produce diazene oxide groups (G) and carbon dioxide (H) [ 29 ]. The reaction was expressed in Equation (3).…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, polyurethane formation in bulk and solution conditions has also been reported from the analysis of characteristic functional group changes based on infrared absorption data [ 22 , 23 ], viscosity change (rheology) [ 11 , 12 , 13 , 14 , 15 , 16 ], magnetic resonance/NMR [ 24 , 25 ], and heat flux [ 18 , 26 ]. Further, polymerization of polyurethane formation from HTPB with IPDI has also been conducted in both bulk and solution conditions [ 18 , 20 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. The polymerization consists of several steps involving two hydroxyl groups in HTPB and two isocyanate groups.…”

Section: Introductionmentioning

confidence: 99%

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Hexogen Coating Kinetics with Polyurethane-Based Hydroxyl-Terminated Polybutadiene (HTPB) Using Infrared Spectroscopy

et al. 2022

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The kinetics of hexogen coating with polyurethane-based hydroxyl-terminated polybutadiene (HTPB) using infrared spectrometry was investigated. The kinetics model was evaluated through reaction steps: (1) hydroxyl and isocyanate to produce urethane, (2) urethane and isocyanate to produce allophanate, and (3) nitro and isocyanate to produce diazene oxide and carbon dioxide. HTPB, ethyl acetate, TDI (toluene diisocyanate), and hexogen were mixed for 60 min at 40 °C. The sample was withdrawn and analyzed with infrared spectroscopy every ten minutes at reference wavelengths of 2270 (the specific absorption for isocyanate groups) and 1768 cm−1 (the specific absorption for N=N groups). The solvent was vaporized; then, the coated hexogen was cured in the oven for 7 days at 60 °C. The effect of temperature on the coating kinetics was studied by adjusting the reaction temperature at 40, 50, and 60 °C. This procedure was repeated with IPDI (isophorone diisocyanate) as a curing agent. The reaction rate constant, k3, was calculated from an independent graphic based on increasing diazene oxide concentration every ten minutes. The reaction rate constants, k1 and k2, were numerically calculated using the Newton–Raphson and Runge–Kutta methods based on decreasing isocyanate concentrations. The activation energy of those steps was 1178, 1021, and 912 kJ mole−1. The reaction rate of hexogen coating with IPDI was slightly faster than with TDI.

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Section: Resultssupporting

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hexogen Coating Kinetics with Polyurethane-Based Hydroxyl-Terminated Polybutadiene (HTPB) Using Infrared Spectroscopy

et al. 2022

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“…While HTPB curing is a thoroughly researched topic, the literature has many inconsistencies. Depending on the formulation, the testing range, or testing conditions, different analyses are used on the same types of polyurethanes. ,− As we demonstrate here, our method is viable across a broad range of formulations in both R-ratios and plasticizer concentrations, with the transitional region well-defined. Other cure analyses are typically fit to an exponential decay, which disrupts accuracy in the transitional region.…”

Section: Introductionmentioning

confidence: 96%

Early Cure Analysis to Inform Direct Ink Writing of HTPB Polyurethane: Insights from Spectroscopy, Rheology, and Molecular Simulations

Strutton,

Moore,

Marcischak

et al. 2023

ACS Appl. Polym. Mater.

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This work analyzed the curing process of hydroxyl-terminated polybutadiene (HTPB) polyurethane networks in a direct ink writing (DIW)-inspired investigation using spectroscopy, rheology, and molecular simulations. Because the bulk performance of DIW-produced specimen is driven by the extrudate surface chemistry and bulk viscoelastic properties, coupled rheology and Fourier-transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy were used to sample critical physics in strategic locations within the material (i.e., at the surface and bulk) simultaneously. Data obtained from FTIR-ATR spectroscopy and rheology yielded similar trends with complementary details at early cure stages (i.e., before gel point), which are critical to the DIW process. Infrared spectroscopy provided valuable information for monitoring surface network conversion, while rheology gave precise information on when the material transitioned to a solid phase via gelation. Molecular simulations provided a predicted ideal curing process to compare relationships between isocyanate ratios and the impact of additional plasticizers on the curing process. The results showed that while adding plasticizer led to changes in both rheological and spectroscopic results, almost no changes were detected in the simulations. Overall, this study emphasizes the importance of better understanding the location-specific reaction process of HTPB polyurethane network formation for high-fidelity DIW implementation through coupled rheology and spectroscopy.

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“…In comparison, aliphatic isocyanates generate products with superior durability under harsh conditions and primarily are used in paint and surface coatings (e.g., automotive, aerospace, military) [10][11][12]. Aliphatic isocyanates also have specialty applications in solid propellants [13,14], polymer bonded explosives [13,15], and medical devices [16,17].…”

Section: Introductionmentioning

confidence: 99%

Glutathione reactivity with aliphatic polyisocyanates

Wisnewski

Liu

2022

PLoS ONE

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Isocyanate chemicals known to cause adverse health effects when inhaled are essential to making important products and are used in multiple industries. Glutathione (GSH), a major antioxidant of the lower airways with a well described role in xenobiotic metabolism, is a primary reaction target for di-isocyantes. However, GSHs reactivity with poly-isocyanates which have largely replaced diisocyanates (particularly aliphatic) in most end-user settings remains uncertain. We hypothesized aliphatic polyisocyanates would readily react with glutathione under physiologic conditions and the products could be identified using liquid chromatography (LC) coupled-mass spectrometry (MS) and tandem MS/MS. The data identified (tris)GSH-isocyanate adducts as the major reaction product of GSH with the most commonly used contemporary polymeric (tri-isocyanate) formulations of hexamethylene diisocyanate (HDI), the isocyanurate and biuret, as [M+H]+ ions of 1426.53 and 1400.55 m/z respectively in reverse phase LC-MS using electrospray in positive ion mode. The uretdione form of HDI, a stabilized dimer, formed two reaction products with GSH, a tris(GSH)-isocyanate reaction product recognized as a 1258.44 m/z [M+H]+ ion, and a bis(GSH)-isocyanate product identified as a 951.36 m/z [M+H]+ ion. Predicted structures for the newly described GSH-polyisocyanate reaction products, modeled based on collision induced dissociation (CID) fragmentation patterns in tandem MS/MS, support S-linkage of the GSH to N = C = O groups. In summary, industrially-used aliphatic polyisocyanates readily react with GSH to form primarily S-linked tris(GSH)-conjugates, a process that may play an important role in response to respiratory tract exposure.

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Curing Reaction Kinetics of the EHTPB-Based PBX Binder System and Its Mechanical Properties

Cited by 8 publications

References 28 publications

Hexogen Coating Kinetics with Polyurethane-Based Hydroxyl-Terminated Polybutadiene (HTPB) Using Infrared Spectroscopy

Hexogen Coating Kinetics with Polyurethane-Based Hydroxyl-Terminated Polybutadiene (HTPB) Using Infrared Spectroscopy

Early Cure Analysis to Inform Direct Ink Writing of HTPB Polyurethane: Insights from Spectroscopy, Rheology, and Molecular Simulations

Glutathione reactivity with aliphatic polyisocyanates

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