TY - JOUR

T1 - How hydrogen bonds influence the slow crack growth resistance of polyamide 12

AU - Messiha, Mario

AU - Frank, Andreas

AU - Arbeiter, Florian

AU - Pinter, Gerald

N1 - Funding Information: The research work of this paper was performed at the Polymer Competence Center Leoben GmbH (PCCL, Austria) within the framework of the K1 COMET-program (Grant Nr.: 879785), which is funded by the Federal Ministry for Transport, Innovation and Technology (Austria) and Federal Ministry for Economy, Family and Youth (Austria) with contributions by Evonik Operations GmbH (Germany) and the Montanuniversitaet Leoben (Austria) . The PCCL is funded by the Austrian Government and the State Governments of Styria and Upper Austria . Publisher Copyright: © 2021 The Authors

PY - 2022/1/17

Y1 - 2022/1/17

N2 - Slow Crack Growth (SCG) is considered to be the most critical failure mode for a variety of long-term applications. A key element within this research was to examine the SCG behaviour of polyamide 12 (PA12). Because hydrogen (H) bonds are well-known to affect the mechanical properties of plastics, such as PA12, special focus was put on their influences during quasi-brittle fracture. Therefore, the total fracture energy Gf of PA12 was divided into a pure chain disentanglement fracture energy, driven by creep processes during SCG (Gdis,f), and the additional energy needed to dissociate effective H-bonds that are actively resisting SCG (GH,f) within PA12. In that context, Gf was calculated from the experimentally measured activation energy for SCG via Cracked Round Bar (CRB) tests at different temperatures and the subsequent use of a time-temperature superposition. Subsequently, GH,f, was estimated with the aid of a modified Sequential Debonding Fracture (SDF) model. Subtracting GH,f from Gf, the remaining energy could be classified as Gdis,f and was calculated for different amounts of effective H-bonds. It was demonstrated for the selected material, that GH,f would become the dominating source of energy which has to be overcome, if at least 45% of all H-bonds crossing the crack plane engage in the fracture process and follow a sequential debonding mechanism.

AB - Slow Crack Growth (SCG) is considered to be the most critical failure mode for a variety of long-term applications. A key element within this research was to examine the SCG behaviour of polyamide 12 (PA12). Because hydrogen (H) bonds are well-known to affect the mechanical properties of plastics, such as PA12, special focus was put on their influences during quasi-brittle fracture. Therefore, the total fracture energy Gf of PA12 was divided into a pure chain disentanglement fracture energy, driven by creep processes during SCG (Gdis,f), and the additional energy needed to dissociate effective H-bonds that are actively resisting SCG (GH,f) within PA12. In that context, Gf was calculated from the experimentally measured activation energy for SCG via Cracked Round Bar (CRB) tests at different temperatures and the subsequent use of a time-temperature superposition. Subsequently, GH,f, was estimated with the aid of a modified Sequential Debonding Fracture (SDF) model. Subtracting GH,f from Gf, the remaining energy could be classified as Gdis,f and was calculated for different amounts of effective H-bonds. It was demonstrated for the selected material, that GH,f would become the dominating source of energy which has to be overcome, if at least 45% of all H-bonds crossing the crack plane engage in the fracture process and follow a sequential debonding mechanism.

KW - Cyclic cracked round bar test

KW - Hydrogen bonds

KW - Micro-deformation mechanisms

KW - Polyamides

KW - Slow crack growth

UR - http://www.scopus.com/inward/record.url?scp=85120885978&partnerID=8YFLogxK

U2 - 10.1016/j.polymer.2021.124437

DO - 10.1016/j.polymer.2021.124437

M3 - Article

AN - SCOPUS:85120885978

VL - 239.2022

JO - Polymer

JF - Polymer

SN - 0032-3861

IS - 17 January

M1 - 124437

ER -