Evolution of material properties during the solvent-assisted recycling of thermosetting polymers: to reduce the residual stress and material inhomogeneity

Shi，X.1,2; Soule，D.1; Ge，Q.3; Lu，H.2; Yu，K.1

2022-11-01

10.1016/j.mtsust.2022.100167

Materials Today Sustainability   Impact Factor & Quartile

2589-2347

Primary recycling of thermosetting polymers is shown to be enabled by depolymerizing the material in a suitable organic solvent and then re-polymerizing it into near-identical networks with equivalent mechanical properties. The re-polymerization process involves sophisticated coupling among solvent diffusion, chemical reaction, and stress field development. Specifically, solvent evaporation leads to restrained volume shrinkage of the resin and residual stress development within the re-polymerized materials. Nonuniform curing degree and material properties are also developed in the direction of solvent diffusion. These impose grand challenges to identify the optimal processing conditions to recycle thermosets with high quality and high speed. In this paper, using an integrated experimental and theoretical approach, the evolutions of the stress field and material properties during the re-polymerization of thermosetting polymers are studied. It shows how to tune the processing temperature to mitigate the residual stress and material inhomogeneity of recycled thermosets. The influencing mechanisms of sample thickness and catalyst content are also revealed. The fundamental understanding is finally extended to study the manufacturing of composites with particle reinforcements using the depolymerized solution, with a particular emphasis on the minimization of the stress concentration around particles. Overall, this study provides a guideline to design material and processing conditions for homogeneous network structure and mechanical properties of recycled thermosets, which will promote the applications of the green recycling method for thermoset wastes and benefit society. (C) 2022 Elsevier Ltd. All rights reserved.

Transesterification Bond exchange reactions Anhydride epoxy Thermoset recycling Mechanical properties

SCI ; EI

English

Others

National Science Founda-tion[CMMI-1901807]

Science & Technology - Other Topics ; Materials Science

Green & Sustainable Science & Technology ; Materials Science, Multidisciplinary

WOS:000850452800007

ELSEVIER

20222612297277

Chemical bonds ; Polymerization ; Residual stresses ; Solvents ; Thermosets

Industrial Wastes:452.3 ; Physical Chemistry:801.4 ; Chemical Agents and Basic Industrial Chemicals:803 ; Organic Polymers:815.1.1 ; Polymerization:815.2

Web of Science

1.Department of Mechanical Engineering,University of Colorado Denver,Denver,80217,United States
2.National Key Laboratory of Science and Technology on Advanced Composites in Special Environments,Harbin Institute of Technology,Harbin,150080,China
3.Department of Mechanical and Energy Engineering,Southern University of Science and Technology,Shenzhen,518055,China

Shi，X.,Soule，D.,Ge，Q.,et al. Evolution of material properties during the solvent-assisted recycling of thermosetting polymers: to reduce the residual stress and material inhomogeneity[J]. Materials Today Sustainability,2022,19.

Shi，X.,Soule，D.,Ge，Q.,Lu，H.,&Yu，K..(2022).Evolution of material properties during the solvent-assisted recycling of thermosetting polymers: to reduce the residual stress and material inhomogeneity.Materials Today Sustainability,19.

Shi，X.,et al."Evolution of material properties during the solvent-assisted recycling of thermosetting polymers: to reduce the residual stress and material inhomogeneity".Materials Today Sustainability 19(2022).