Abstract
Melt reactive processing of lignin with nitrile rubber is a promising approach to synthesizing shape memory materials. The strong intramolecular interactions in lignin macromolecular structures, caused by π-π stacking in aromatic rings and hydrogen bonding, often result in large phase separation or low miscibility with rubbers. In this study, we investigated the chemical and molecular characteristics, as well as the stiffness and complex viscosity, of modified kraft lignin melt-reacted with an acrylonitrile/butadiene copolymer containing 41% acrylonitrile (NBR41). To enhance the macromolecular compatibility of kraft lignin with NBR41, kraft lignin was cross-linked with poly(propylene glycol) diglycidyl ether (PPDE) and trimethylolpropane triglycidyl ether (TTE), both rich in epoxy reactive groups capable of forming chemical bonds with hydroxyl and carboxyl groups. Our findings demonstrate that the modification of kraft lignin with PPDE and TTE resulted in significantly increased stiffness of the composites. The elastic modulus of NBR41-Kraft lignin-PPDE and NBR41-Kraft lignin-TTE increased by 82 and 162%, respectively. Both the yield strength and Young’s modulus of these two samples showed dramatic improvements. Specifically, the yield strength and Young’s modulus of NBR41-Kraft lignin-TTE increased nearly 4 and 3-fold, respectively, compared to the control sample. Interestingly, despite significant improvements in mechanical properties, the viscosity of NBR41-Kraft lignin-PPDE was substantially lower than that of the control sample. At 210 °C and an angular frequency of 1 rad/s, the complex viscosity of NBR41-Kraft lignin was approximately 100.25 ± 4.77 kPa·s, while that of NBR41-Kraft lignin-PPDE was significantly lower at 56 ± 0.93 kPa·s. These findings were validated through Fourier transform infrared spectroscopy, scanning electron microscopy, dynamic mechanical analysis, thermal characterization, rheological tests, and quasi-elastic neutron scattering techniques.
| Original language | English |
|---|---|
| Journal | ACS Applied Polymer Materials |
| DOIs | |
| State | Accepted/In press - 2025 |
Funding
Work at ORNL\u2019s Spallation Neutron Source and Center for Nanophase Materials and Sciences was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. The beam time was allocated to BASIS (BL-2) on proposal IPTS-30712. Electron Microscopy was performed at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for U.S. DOE under Contract No. DEAC05-00OR22725. We thank Professor Jeff Baur in the Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, for the Brabender mixer access. We also thank the Illinois Applied Research Institute Laboratory, the Materials Research Laboratory, and the Advanced Material Testing and Evaluation Laboratory, University of Illinois at Urbana-Champaign, for their facility access.This work was supported by the Illinois Applied Research Institute within the Grainger College of Engineering at the University of Illinois, Urbana-Champaign. Work at ORNL\u2019s Spallation Neutron Source and Center for Nanophase Materials and Sciences was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. The beam time was allocated to BASIS (BL-2) on proposal IPTS-30712. Electron Microscopy was performed at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for U.S. DOE under Contract No. DEAC05-00OR22725. We thank Professor Jeff Baur in the Department of Aerospace Engineering, University of Illinois at Urbana\u2013Champaign, for the Brabender mixer access. We also thank the Illinois Applied Research Institute Laboratory, the Materials Research Laboratory, and the Advanced Material Testing and Evaluation Laboratory, University of Illinois at Urbana\u2013Champaign, for their facility access.
Keywords
- lignin
- molecular dynamics
- nitrile butadiene rubber composites
- quasielastic neutron scattering
- shape memory polymers