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

• Published in: Polymer (Guilford) Vol. 107; pp. 233 - 239
• Main Authors: Lempesis, Nikolaos, in ‘t Veld, Pieter J., Rutledge, Gregory C.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 19.12.2016; Elsevier BV
• Subjects: Atomistic simulation; Butanediol; Chains; Chains (polymeric); Computer simulation; Crystal elasticity; Crystal structure; Crystals; Deformation; Diisocyanates; Diphenyl methane diisocyanate; Dynamic mechanical properties; Elasticity; MDI; Molecular dynamics; Molecular structure; Polycrystals; Polyurethane; Polyurethane resins; Simulation; Stiffness matrix; Stress-strain curves; Stress-strain relationships; Urethane thermoplastic elastomers; Atomistic simulation; Crystal elasticity; Polyurethane
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2016.11.021

We report molecular simulation, at the atomistic level, of crystalline 4,4′-diphenylmethane diisocyanate (MDI) with n-butanediol (BDO) as chain extender, henceforth denoted as MDI/BDO, which is one of the most important components of thermoplastic polyurethanes. This work studies the structure and properties of crystalline MDI/BDO at equilibrium and under deformation. An atomistic molecular model of the MDI/BDO unit cell was constructed from fractional coordinates available for related model compounds and space group symmetry, and bulk properties of the subsequently equilibrated crystal were estimated by molecular dynamics. Overall stress-strain behavior of the crystal to small strains was simulated. The full stiffness matrix of crystalline MDI/BDO was extracted, allowing for the complete characterization of the linear elastic behavior of the crystal. [Display omitted] •An atomistic model is presented for crystalline 4,4’-diphenylmethane diisocyanate (MDI) with n-butanediol (BDO) as chain extender.•This model of MDI/BDO l is validated against experimental data.•The full elastic stiffness tensor of MDI/BDO is calculated from molecular dynamics simulations.•The mechanics of this material plays a crucial role as the hard component of an important class of thermoplastic polyurethanes.