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Effect of Polypropylene Grafted Maleic Anhydride (PP-G-MAH) on the Properties of Asphalt and its Mixture Modified With Recycled Polyethylene/Recycled Polypropylene (RPE/RPP) Blends

Frontiers in Materials 2022 11 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Wencai Zhang, Xiaogang Hao, Chang-Xin Fan, Shuai Zhang, Dechong Ma, Xiaofang Yu, Zhaohua Fu, Gongji Feng

Summary

Researchers prepared a ternary blend modifier (TBM) from recycled polyethylene, recycled polypropylene, and varying dosages of polypropylene grafted maleic anhydride (PP-g-MAH) and assessed its performance as an asphalt modifier. Increasing PP-g-MAH content reduced penetration and improved softening point and viscosity, with 7% PP-g-MAH showing optimal compatibility and enhanced high-temperature rutting resistance in asphalt mixtures.

Polymers

In this study, a ternary blend modifier (TBM) was prepared with RPE, RPP, and various dosages of PP-g-MAH (i.e., 0%, 1%, 3%, 5%, 7%, and 9% by weight of RPE and RPP) by a twin-screw extruder. The performance of TBM (4% by weight of asphalt) modified asphalt was studied, with the increase of PP-g-MAH content, the penetration decreases gradually, but softening point and viscosity increases and ductility exists minimum value at 7% content, with the increasing of PP-g-MAH percentage, the dynamic rheological properties show that |G*| increases, while the δ and |G*|cosδ decrease, and the fatigue performance (|G*|sinδ) of TBM modified asphalt is worse than virgin asphalt. Dynamic stability test shows that TBM shows the prominent high-temperature properties of a modified (asphalt mixture. BBR test indicates that the m-value of asphalt modified with TBM does not fulfill the requirements (m-value>0.3) except at 5% and 7%, but the S meets the standard requirements (S < 300 MPa), and increases from 0% to 7%, then decreases slightly. In order to illuminate possible reasons, a chemical reaction (ester compounds generated) and physical twines of concerned polymer molecules were put forward, and the results were confirmed by infrared analysis.

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