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Degradable bio-based epoxy vitrimers based on imine chemistry and their application in recyclable carbon fiber composites

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Traditional epoxy resin materials are widely used in coatings, composite materials, electronic packaging materials, etc. They are usually made of unsustainable fossil resources and cannot be recycled under mild conditions. Degradable thermosetting resins with dynamic covalent structure provide a potential solution to this conflict. In this paper, using biomass energy vanillin, m-xylylenediamine and 1, 6-hexanediamine as raw materials, two dynamic imine bond curing agents were synthesized, and then cured with DGEBA to prepare two bio-based imine epoxy vitrimers. The thermal and mechanical properties of two imine epoxy vitrimers were studied and compared in detail. Results showed that the two types of polymers exhibit excellent thermal stability and solvent resistance. At the same time, the tensile strength, modulus and elongation at break were comparable to or even better than those of conventional bisphenol A epoxy resin. In addition, due to the hydrolysis of the dynamic imine bonds, vitrimers had degradable characteristic, and its degradation also exhibited temperature, solvent and acidity dependence. More importantly, the recyclable carbon fiber reinforced polymer composites made of these two vitrimers could be completely degraded under weak acid conditions, and the nondestructive recycling of carbon fiber composites could be realized. We envision that this vitrimers with simple process, excellent comprehensive properties and degradability will make it a potential candidate for applications in sustainable structural materials.
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COMPOSITES & NANOCOMPOSITES
Degradable bio-based epoxy vitrimers based on imine
chemistry and their application in recyclable carbon
fiber composites
Xiaohong Liu
1,2,5
, Ending Zhang
1,5
, Zhiqiang Feng
1,5
, Jiaming Liu
2,5
, Bifang Chen
1,4
, and
Liyan Liang
1,2,3,4,5,
*
1
Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650, People’s Republic of China
2
Guangdong Provincial Key Laboratory of Organic Polymer Materials for Electronics, Guangzhou 510650, People’s Republic of
China
3
CAS Engineering Laboratory for Special Fine Chemicals, Guangzhou 510650, People’s Republic of China
4
CASH GCC (Nanxiong) Research Institute of New Materials Co, Ltd, Nanxiong 512400, People’s Republic of China
5
University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
Received: 6 April 2021
Accepted: 21 June 2021
Published online:
7 July 2021
ÓThe Author(s), under
exclusive licence to Springer
Science+Business Media, LLC,
part of Springer Nature 2021
ABSTRACT
Traditional epoxy resin materials are widely used in coatings, composite mate-
rials, electronic packaging materials, etc. They are usually made of unsustainable
fossil resources and cannot be recycled under mild conditions. Degradable ther-
mosetting resins with dynamic covalent structure provide a potential solution to
this conflict. In this paper, using biomass energy vanillin, m-xylylenediamine and
1, 6-hexanediamine as raw materials, two dynamic imine bond curing agents
were synthesized, and then cured with DGEBA to prepare two bio-based imine
epoxy vitrimers. The thermal and mechanical properties of two imine epoxy
vitrimers were studied and compared in detail. Results showed that the two types
of polymers exhibit excellent thermal stability and solvent resistance. At the same
time, the tensile strength, modulus and elongation at break were comparable to or
even better than those of conventional bisphenol A epoxy resin. In addition, due
to the hydrolysis of the dynamic imine bonds, vitrimers had degradable charac-
teristic, and its degradation also exhibited temperature, solvent and acidity
dependence. More importantly, the recyclable carbon fiber reinforced polymer
composites made of these two vitrimers could be completely degraded under
weak acid conditions, and the nondestructive recycling of carbon fiber composites
could be realized. We envision that this vitrimers with simple process, excellent
comprehensive properties and degradability will make it a potential candidate for
applications in sustainable structural materials.
Handling Editor: Annela M. Seddon.
Address correspondence to E-mail: lyliang@gic.ac.cn
https://doi.org/10.1007/s10853-021-06291-5
J Mater Sci (2021) 56:15733–15751
Composites & nanocomposites
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... [14] The second group includes the development of novel thermoset materials that are easy to reprocess, repair, and degrade. Dynamic covalent bonds such as Diels-Alder (DA) adducts, [15,16] disulfides, [17][18][19][20] imines, [21,22] hydroxyl-esters [23][24][25] etc. have been introduced into the cross-linking network of novel thermoset materials. They can decompose or react reversibly under heating or other external stimuli (heat, light, mechanical force, p H , solvent, etc.). ...
... The same researchers also synthesized and compared two reversible imine bond-containing curing agents using sustainable vanillin, aromatic diamine, and aliphatic diamine as precursors, and then combined them with DGEBA. [22] Both thermosets have remarkable heat and chemical stability. Simultaneously, mechanical attributes such as stress, strain, and modulus were equivalent to or better than those of the standard DGEBA epoxy resin. ...
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... 93 In a similar study, two different imine exchange based vitrimers were synthesized using vanillin/1,6-hexylenediamine (VHP) and vanillin/m-xylylenediamine (VMP) curing agents. 94 The tan d result shows that the T g of VHP and VMP bio-based imine epoxy vitrimers are 83°C and 96°C, respectively, whereas the storage modulus values are 2600 MPa and 2650 MPa, respectively. This could be attributed to the higher rigidity chain structure for VMP vitrimer ( Fig. 12a and b). ...
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