Plane stress fracture toughness of physically aged plasticized PETG as assessed by the essential work of fracture (EWF) method |
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Authors: | J. Karger-Kocsis,T. Bá rá nyE.J. Moskala |
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Affiliation: | a Institut für Verbundwerkstoffe GmbH, Technische Universität Kaiserslautern, P.O. Box 3049, D-67653 Kaiserslautern, Germany b Department of Polymer Engineering and Textile Technology, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, H-1111 Budapest, Hungary c Eastman Chemical Co., Research Laboratories, Kingsport, TN 37662-5150, USA |
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Abstract: | The plane stress fracture toughness of amorphous copolyester (PETG) sheets plasticized by various amount of neopentylglycol dibenzoate (NPGDB in 0, 5, 10 and 20 wt%) was studied in as-received (AR) and rejuvenated (RJ) states by adopting the essential work of fracture (EWF) method. EWF tests were performed on deeply double-edge notched tensile loaded (DDEN-T) specimens at various deformation rates (2,10 and 100 mm/min) at room temperature. It was established that physical aging strongly affected the EWF terms. The specific yielding-related EWF increased with increasing deformation rate and decreased with increasing plasticizer content. The specific non-essential work and its necking-related constituent, which changed parallel to each other, remained constant up to 10 wt% NPGDB content and decreased afterwards. The plastic zone in the DDEN-T specimens was formed by cold drawing which is governed by the entanglement structure. This was demonstrated by the shape recovery of the plastic zone in the broken DDEN-T specimens after heating them above the Tg of the related PETG compound. |
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Keywords: | Amorphous copolyester Plasticizer Essential work of fracture (EWF) |
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