Simulation of the structure and mechanics of crystalline 4,4′-diphenylmethane diisocyanate (MDI) with n-butanediol (BDO) as chain extender

Lempesis, Nikolaos; Veld, Pieter J. in ’t

doi:10.1016/j.polymer.2016.11.021

Cited by 24 publications

(34 citation statements)

References 52 publications

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“…The force fields were previously validated on simulations of semicrystalline PTMO, 13 and crystalline MDI/BDO. 12 Atomistic configurations of TPUs were created using the IMC method, having a crystalline MDI/BDO layer and an amorphous PTMO layer. In general, the model created by the IMC method is a one-dimensional lamellar stack that consists of noncrystalline domains sandwiched between crystalline domains, as shown in Figure 1.…”

Section: System and Methodsmentioning

confidence: 99%

Molecular Simulation of Thermoplastic Polyurethanes under Large Compressive Deformation

2018

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Thermoplastic polyurethanes (TPUs) are candidates for a number of applications where outstanding resilience and ability to dissipate energy under large compressive deformation are needed. TPUs possess complex, heterogeneous structure where chemically distinct segments segregate into hard and soft domains, which pose significant challenges for the molecular level mechanistic understanding of their mechanical properties, and associated multi-scale modeling and experimentation. In this

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Section: System and Methodsmentioning

confidence: 99%

Molecular Simulation of Thermoplastic Polyurethanes under Large Compressive Deformation

2018

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“…However, TPU presents stronger small sharp peaks at the top of a broad amorphous halo compared to the composites and these signals are displayed in the 2θ ranges 9-11 • and 20-30 • . The diffraction peak at 2θ = 10 • gives information about the unit cell projection along the c axis while the peak at 20 • represents the interchain distance between two chains lying in the ac-plane and spaced by hydrogen bonds [36]. Finally, the peaks in the range 21-25 • give information about the distance among adjacent hydrogen bonded sheets (intersheet distance) [36,37].…”

Section: Samplementioning

confidence: 99%

“…The diffraction peak at 2θ = 10 • gives information about the unit cell projection along the c axis while the peak at 20 • represents the interchain distance between two chains lying in the ac-plane and spaced by hydrogen bonds [36]. Finally, the peaks in the range 21-25 • give information about the distance among adjacent hydrogen bonded sheets (intersheet distance) [36,37]. The intensities of these peaks reduce for TPU-Chit and TPU-Ag until disappearing for TPU-TiO 2 .…”

Section: Samplementioning

confidence: 99%

Polyurethane-Based Composites: Effects of Antibacterial Fillers on the Physical-Mechanical Behavior of Thermoplastic Polyurethanes

et al. 2020

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The challenge to manufacture medical devices with specific antibacterial functions, and the growing demand for systems able to limit bacterial resistance growth, necessitates the development of new technologies which can be easily produced at an industrial level. The object of this work was the study and the development of silver, titanium dioxide, and chitosan composites for the realization and/or implementation of biomedical devices. Thermoplastic elastomeric polyurethane was selected and used as matrix for the various antibacterial functions introduced during the processing phase (melt compounding). This strategy was employed to directly incorporate antimicrobial agents into the main constituent material of the devices themselves. With the exception of the composite filled with titanium dioxide, all of the other tested composites were shown to possess satisfactory mechanical properties. The best antibacterial effects were obtained with all the composites against Staphylococcus aureus: viability was efficiently inhibited by the prepared materials in four different bacterial culture concentrations.

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“…70,71 In this work, CIM was used in the forward direction to estimate the elasticity of a TPU based on the elasticities of its relatively simpler constituent parts: a layer of semicrystalline PTMO 21 and a layer of crystalline MDI/BDO. 22 In the TPU system of Figure 2, the outermost layers are both crystalline MDI/BDO; due to periodic boundary conditions imposed in our model, those two layers may be treated as part of the same layer. Although, there are various other micromechanical homogenization techniques in the literature, such as the double-inclusion method (DIM) developed by Hori and Nemat-Nasser, 72 CIM has the advantage that no Eshelby tensor or random reference medium is needed, resulting in fewer independent variables that need to be determined.…”

Section: Micromechanical Homogenizationmentioning

confidence: 99%

Atomistic Simulation of a Thermoplastic Polyurethane and Micromechanical Modeling

Lempesis

Veld

2017

Macromolecules

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Thermoplastic polyurethanes constitute a versatile family of materials with a broad variety of engineering applications. However, connection between their chemical structure and mechanical properties remains elusive, in large part due to their heterogeneous nature, arising from segregation of chemically distinct segments into separate domains, with resulting complex morphologies. Using atomistic simulations, we examine the structure and mechanical properties of a common family of thermoplastic polyurethanes (TPU) comprising 4,4′-diphenylmethane diisocyanate and n-butanediol (hard segment) and polytetramethylene oxide (soft segment). A lamellar stack model previously developed for the study of semicrystalline polymers is applied here for the first time to a phase-segregated copolymer. Equilibrium structure and properties were evaluated for TPUs with different ratios of hard and soft components, using a combination of Monte Carlo and molecular dynamics simulations. Stress-strain behaviors were then evaluated using nonequilibrium molecular dynamics (NEMD) simulations. The compositional dependence of the Young's moduli thus obtained is shown to be well-approximated by a micromechanical homogenization model of the hard and soft components. Voigt (upper) and Reuss (lower) bounds of modulus were obtained for orientationally averaged aggregates, and shown to be greater than those measured experimentally. The discrepancy is explained in terms of the strain rate dependence of elastic moduli, characterized by an Eyring-like function.

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Simulation of the structure and mechanics of crystalline 4,4′-diphenylmethane diisocyanate (MDI) with n-butanediol (BDO) as chain extender

Abstract: Simulation of the structure and mechanics of crystalline 4,4#-diphenylmethane diisocyanate (MDI) with n-butanediol (BDO) as chain extender The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters.

Cited by 24 publications

References 52 publications

Molecular Simulation of Thermoplastic Polyurethanes under Large Compressive Deformation

Molecular Simulation of Thermoplastic Polyurethanes under Large Compressive Deformation

Polyurethane-Based Composites: Effects of Antibacterial Fillers on the Physical-Mechanical Behavior of Thermoplastic Polyurethanes

Atomistic Simulation of a Thermoplastic Polyurethane and Micromechanical Modeling

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