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621 results on '"Liu, Ying Ling"'

9. Is a Vitrimer with a High Glass Transition Temperature Available? A Case Study on Rigid Polyimides Cross‐Linked with Dynamic Ester Bonds.

Author

Wang, Yueh‐Hsin, Hung, Du‐Yuan, and Liu, Ying‐Ling

Subjects
TRANSITION temperature, THERMAL properties, DIFFUSION control, HIGH temperatures, WASTE recycling
Abstract

Vitrimers, possessing associative covalent adaptable networks, are cross‐linked polymers exhibiting malleable (glass‐like) feature and recyclable and reprocessable (thermoplastics‐like) properties. The dynamic behaviors of vitrimer are dependent on both chain/molecular mobility (glass transition temperature, Tg) and dynamic bond‐exchanging reaction rate (topology freezing transition temperature, Tv). This work aims on probing the effect of high Tg on the stress relaxation and physical recyclability of vitrimers, employing a polyimide cross‐linked with dynamic ester bonds (Tg: 310 °C) as the example. Due to its high Tg and chain rigidity, the cross‐linked polyimide does not exhibit a high extent of stress relaxation behavior at 320 °C (10 °C above its Tg), even though the temperature is much higher than the hypothetical Tv. While raising the processing temperature to 345 °C, the cross‐linked polyimide exhibits a stress relaxation time of about 3300 s and physical malleability. Nevertheless, side reactions may occur in the recycling and reprocessing process under the harsh condition (high temperature and high pressure) to alter the thermal properties of the recycled sample. The diffusion control plays a critical role on the topography transition of a vitrimer having a high Tg. The Tg ceiling is noticeable for developments of vitrimers. [ABSTRACT FROM AUTHOR]

Published
2024
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43. BPBM: An Algorithm for String Matching with Wildcards and Length Constraints

Author

Hong, Xiao-Li, Wu, Xindong, Hu, Xue-Gang, Liu, Ying-Ling, Gao, Jun, Wu, Gong-Qing, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Goebel, Randy, editor, Siekmann, Jörg, editor, Wahlster, Wolfgang, editor, Sakai, Hiroshi, editor, Chakraborty, Mihir Kumar, editor, Hassanien, Aboul Ella, editor, Ślęzak, Dominik, editor, and Zhu, William, editor

Published
2009
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44. Poly(ester amide)s from biomass‐based 3,4‐dihydrocoumarine through Meldrum's acid mediated ketene chemistry

Author

Fan, Zhang‐Jun and Liu, Ying‐Ling

Abstract

Meldrum's acid mediated ketene chemistry (MAMKC) is applied to synthesis of poly(ester amide)s in this work. An MA‐functionalized phenolic amide compound (MA_PhOH‐Am) is synthesized from the reaction between a MA‐functionalized amine and 3,4‐dihydrocoumarine (DHC, a biomass‐based chemical) through amine‐lactone addition reaction. Polymerization of MA_PhOH‐Am results in the corresponding poly(ester amide) (P(Es‐Am)), through MA thermolysis reaction (generating the corresponding ketene groups) and ketene‐phenol addition reaction. Both MA_PhOH‐Am and P(Es‐Am) have been characterized with spectral methods and thermal analysis. P(Es‐Am) has an inherent viscosity of 0.49 dL g−1, a molecular weight of 76,500 Da, a glass transition temperature of 145°C (tanδpeak in dynamic mechanical analysis), a thermal stability of about 320°C, and a storage modulus at 50°C of 1.0 GPa. In the stress–strain measurement, P(Es‐Am) exhibits a Young's modulus, a tensile strength, and an elongation at break of 10.6 ± 0.7 GPa, 165 ± 40 MPa, and 1.83 ± 0.41%, respectively. An effective approach for the synthesis of high‐performance poly(ester amide)s has been demonstrated.

Published
2023
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