Microstructure, brittle–ductile transition temperature and elevated temperature compressive behavior of the directionally solidified NiAl–Cr(Mo)–Hf alloy

2004 ◽  
Vol 385 (1-2) ◽  
pp. 359-366 ◽  
Author(s):  
C CUI ◽  
J GUO ◽  
H YE
Keyword(s):  
Transition Temperature ◽  
Elevated Temperature ◽  
Compressive Behavior ◽  
Directionally Solidified ◽  
Brittle Ductile Transition

scholarly journals Epoxy-Anhydride Vitrimers from Aminoglycidyl Resins with High Glass Transition Temperature and Efficient Stress Relaxation

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1148 ◽  
Author(s):  
Michael Giebler ◽  
Clemens Sperling ◽  
Simon Kaiser ◽  
Ivica Duretek ◽  
Sandra Schlögl
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Elevated Temperature ◽  
Glass Transition Temperature ◽  
Stress Relaxation ◽  
Covalent Bond ◽  
Service Temperature ◽  
Exchange Reactions ◽  
Structural Applications ◽  
Relaxation Measurements

Epoxy-anhydride vitrimers are covalent adaptable networks, which undergo associative bond exchange reactions at elevated temperature. Their service temperature is influenced by the glass transition temperature (Tg) as well as the topology freezing transition temperature (Tv), at which the covalent bond exchange reactions become significantly fast. The present work highlights the design of high-Tg epoxy-anhydride vitrimers that comprise an efficient stress relaxation at elevated temperature. Networks are prepared by thermally curing aminoglycidyl monomers with glutaric anhydride in different stoichiometric ratios. The tertiary amine groups present in the structure of the aminoglycidyl derivatives not only accelerate the curing reaction but also catalyse the transesterification reaction above Tv, as shown in stress relaxation measurements. The topology rearrangements render the networks recyclable, which is demonstrated by reprocessing a grinded powder of the cured materials in a hot press. The epoxy-anhydride vitrimers are characterised by a high Tg (up to 140 °C) and an adequate storage modulus at 25 °C (~2.5 GPa), which makes them interesting candidates for structural applications operating at high service temperature.

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