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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 9: Crystallization, Nucleation and Self-Assembly II

CPP 9.1: Vortrag

Montag, 18. März 2024, 15:00–15:15, H 2032

Branches, Tie Chains and Entanglements in Bimodal Polyethylene Single Crystals under Uniaxial Tensile Strain — William S. Fall¹, Jörg Baschnagel², and •Hendrik Meyer² — ¹Laboratoire de Physique des Solides - UMR 8502, CNRS, Université Paris-Saclay, 91405 Orsay, France — ²Institut Charles Sadron - UPR22, CNRS, Université de Strasbourg, France

Short chain branched, bimodal polyethylene resins are relatively resistant to failure, due to their base material strength, when compared to other unimodal or linear compounds. The relationship between molecular level architecture and the mechanical properties of bimodal, branched PE resins is however relatively poorly understood. Using coarse-grained molecular dynamics simulations and a united-monomer model of PE, single well-aligned multi-lamella PE crystals are grown [1], using self-seeding and drawn to mimic uniaxial tensile testing. During deformation, the crystallinity, tie-chain and entanglement content are continuously monitored and correlated with the stress-strain curves obtained and mechanical properties. In addition, the dependence of all metrics on the rate of deformation and direction of drawing are also investigated, such a study is only possible due to the well-aligned PE crystals utilized here [1]. The elastic modulus of well-aligned PE crystals is strongly dependent on the direction of deformation. In the equivalent multi-domain systems, grown by continuous-cooling, such trends are almost completely hidden.

[1] Fall, W. S.; Baschnagel, J.; Benzerara, O.; Lhost, O.; Meyer, H. ACS Macro Letters 2023, 12, 808-813.

Keywords: polymer crystallization; mechanical properties under deformation; molecular dynamics simulation