Degradation-Grafting Mechanochemical Treatment of Recycled Polypropylene as an Asphalt Modifier: Rheological Behavior and Microscopic Mechanisms
6 affiliations
- 1Hubei United Transportation Industrial Development Co., Ltd., Wuhan 430056, China
- 2Wuhan Metropolitan Area Investment and Development Group Co., Ltd., Hubei Communications Investment Group Co., Ltd., Wuhan 430040, China
- 3School of Civil Engineering and Architecture, Wuhan Institute of Technology, Wuhan 430074, China
- 4Hubei Provincial Engineering Research Center for Green Civil Engineering Materials and Structures, Wuhan Institute of Technology, Wuhan 430074, China
- 5College of Civil Engineering, Fuzhou University, Fuzhou 350108, China
- 6School of Materials Science and Engineering, Chang’an University, Xi’an 710061, China
Abstract
As a common solid waste, recycled polypropylene (RPP) has been demonstrated to be a viable asphalt modifier for enhancing pavement performance. However, its direct application still faces bottlenecks including high processing temperatures, poor dispersion, and unstable performance, which hinder its potential promotion. To address this, this study adopted a mechanochemical treatment of RPP with varying dosages of di-cumyl peroxide (DCP) and epoxidized soybean oil (ESO) to prepare a novel waste plastic asphalt modifier. This process was designed to cleave the long molecular chains of RPP via DCP, while simultaneously allowing dynamic chemical grafting reactions with ESO, yielding a degraded WPP bearing flexible functional groups. Through rheological temperature and frequency sweeps, Fourier transform infrared spectroscopy (FTIR), and mechanistic analysis, the intrinsic correlation between the microstructure and macroscopic rheological behavior of the modified binder was systematically investigated. Among the investigated formulations, the results indicated that 0.3RPP-MA showed the highest viscoelastic transition temperature, 25.7 °C, compared with 7.8 °C for the virgin binder. The dynamic shear rheology (DSR) results indicate that this formulation provided the most favorable high-temperature rheological response within the tested DCP range. FTIR spectra clearly verified the formation of ESO graft copolymers and the functional group changes induced by DCP degradation, and a reaction mechanism involving simultaneous degradation and grafting was elucidated. Overall, the preparation method proposed in this study provides a comprehensive analysis of the rheological properties of RPP-modified asphalt, providing both engineering guidance and theoretical support for the high-value utilization of waste plastics.
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BibTeX
@article{zhong2026degradationgrafting,
title = {{Degradation-Grafting Mechanochemical Treatment of Recycled Polypropylene as an Asphalt Modifier: Rheological Behavior and Microscopic Mechanisms}},
author = {Jun Zhong and Xiong Xu and Sha Wu and Hui Tong and Shuang Zhou and Jie Liu and Song Xu and Zongwu Chen},
journal = {Polymers},
year = {2026},
month = oct,
doi = {10.3390/polym18202545},
url = {https://www.mdpi.com/2073-4360/18/20/2545},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Degradation-Grafting Mechanochemical Treatment of Recycled Polypropylene as an Asphalt Modifier: Rheological Behavior and Microscopic Mechanisms
AU - Jun Zhong
AU - Xiong Xu
AU - Sha Wu
AU - Hui Tong
AU - Shuang Zhou
AU - Jie Liu
AU - Song Xu
AU - Zongwu Chen
PY - 2026
DA - 2026/10/16
JO - Polymers
DO - 10.3390/polym18202545
UR - https://www.mdpi.com/2073-4360/18/20/2545
AB - As a common solid waste, recycled polypropylene (RPP) has been demonstrated to be a viable asphalt modifier for enhancing pavement performance. However, its direct application still faces bottlenecks including high processing temperatures, poor dispersion, and unstable performance, which hinder its potential promotion. To address this, this study adopted a mechanochemical treatment of RPP with varying dosages of di-cumyl peroxide (DCP) and epoxidized soybean oil (ESO) to prepare a novel waste plastic asphalt modifier. This process was designed to cleave the long molecular chains of RPP via DCP, while simultaneously allowing dynamic chemical grafting reactions with ESO, yielding a degraded WPP bearing flexible functional groups. Through rheological temperature and frequency sweeps, Fourier transform infrared spectroscopy (FTIR), and mechanistic analysis, the intrinsic correlation between the microstructure and macroscopic rheological behavior of the modified binder was systematically investigated. Among the investigated formulations, the results indicated that 0.3RPP-MA showed the highest viscoelastic transition temperature, 25.7 °C, compared with 7.8 °C for the virgin binder. The dynamic shear rheology (DSR) results indicate that this formulation provided the most favorable high-temperature rheological response within the tested DCP range. FTIR spectra clearly verified the formation of ESO graft copolymers and the functional group changes induced by DCP degradation, and a reaction mechanism involving simultaneous degradation and grafting was elucidated. Overall, the preparation method proposed in this study provides a comprehensive analysis of the rheological properties of RPP-modified asphalt, providing both engineering guidance and theoretical support for the high-value utilization of waste plastics.
SN - 2073-4360
ER -