Mechanism on natural raw rubber network construction via ternary deep eutectic solvent combined with foaming dispersion microwave irradiation process

In this paper, a hydrogen bond network-enhanced ternary deep eutectic solvent (CGG-DES) was prepared using bio-based glycerol and gallic acid as dual hydrogen bond donors. Under the synergistic effect of porous channel construction through foaming expansion of natural rubber latex and enhanced reverse dehydration of water from the interior to the surface by microwave irradiation, a raw rubber network composed of an entanglement network, a hydrogen bonding network, and a chemical network was affected, improving the overall performance of the raw rubber and composites. Meanwhile, fresh natural rubber latex (FNRL) and concentrated natural rubber latex (CNRL) with different contents of non-rubber components were selected for comparative experiments. FTIR demonstrated that CGG-DES possessed a strong hydrogen bonding network and generated physicochemical interactions with the protein protective layer of rubber particles. With the participation of an appropriate amount of CGG-DES, the network density of the constructed raw rubber network increased, the molecular chains became more flexible, the molecular weight increased, and the molecular weight distribution became broader. Furthermore, the total crosslink density and mono/disulfide crosslink density determined by the swelling method also increased, while the aging resistance, mechanical properties, and dynamic properties were improved. Compared with acid-coagulated rubber composites, the tensile strength of 0.5 CGG/FNR and 0.5 CGG/CNR composites increased 31% and 21%, respectively, with a higher storage modulus under dynamic stress. The research provides a new method for the green modification and efficient drying of natural rubber.