Effect Of Annealing Method And Chemical Reaction On The Structure And Properties Of Polyethylene/Polyethylene Glycol Modified Bitumen

Polyethylene (PE) and polyethylene glycol (PEG) are employed to modify bitumen. The rheological stability is revealed by complex modulus (G*) variation with temperature, and it is found that the starting temperature and stable value of G* plateau can be regulated by different annealing treatments. The sample annealed under the temperature (100 degrees C) close to the crystallization temperature of PE has the best rheological stability. The reason for this effect is explored on terms of crystallization behavior of PE, whose crystallinity is related to the stiffness of PE-rich network induced by viscoelastic phase separation. When the PEG modifier is partially replaced by the same fraction of 4,4'-diphenylmethane diisocyanate (MDI), the complex modulus, thermal stability and solvent resistance of PE modified bitumen can be significantly improved, while the PE-rich network structure is refined. The main reason for these results is the chemical reaction between MDI and polar groups of PEGs and/or bitumen to form large-scale urethane/urea structure, which is revealed by Fourier transform infrared spectrometer. (C) 2020 Elsevier Ltd. All rights reserved.