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Poor storage stability is a key problem restricting the rapid development and wide application of rubber-modified asphalt binder, and activation of rubber has shown good prospects to solve this problem. In this study, two activation methods, coating by polyamide 6 and grafting by acrylamide, were introduced to treat crumb rubber. Then the activated rubber was added to base asphalt binder to prepare modified asphalt binder. The chemical structure and morphology of rubber powder before and after activation and of asphalt binder before and after modification were characterized by Fourier transformation infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The conventional and rheological properties and storage stability were analyzed to reveal the influence of activation method on the performance of asphalt binder. The results showed that after being activated, the surface of the rubber is loose and rough. A chemical reaction did not occur during activation by polyamide but occurred during activation by acrylamide. The activation of the rubber effectively improved the high- and low-temperature performance, and the softening difference decreased by 79.8%. This is because the interaction between rubber and asphalt binder was enhanced through activation of rubber, and grafting activation had better effect due to the chemical reaction between the basic amide groups of acrylamide and acid groups of asphalt binder.

A nano-engineered hierarchical composite with localized toughening and integrated damage sensing capabilities is described. Thermoplastic phenoxy interleaves which dissolve in epoxy resin upon heating and subsequently phase separate upon curing were employed as carrier films for localized deposition of carbon nanotubes in carbon fibre–reinforced plastics, avoiding filtration of carbon nanotubes during liquid resin infusion. Interlaminar fracture toughness was improved compared to reference epoxy-based laminates, while the introduced carbon nanotube network was utilized for in situ damage sensing purposes. Using this technology based on dissolvable thermoplastic carrier films, nanofillers can be easily introduced into fibre-reinforced composites at desired regions while simultaneously avoiding typical nanofiller drawbacks such as filtering or increased resin viscosity.

The nature of filler–polymer and filler–filler interactions in rubber composites under strain remains an open question in soft matter physics. These interactions are key to explaining the rich variety of complex behavior exhibited by particle-filled rubber products. In this paper we demonstrate a simultaneous dielectric/dynamic mechanical analysis technique (SDMS) which provides new insights into the structure–property relationships of filled rubbers. The complex permittivity of carbon black filled natural rubber has been characterized under a simultaneous tensile strain field (from 0.1% to 50%). The complex permittivity exhibits a dramatic nonlinear dependence on strain coupled with features which are analogous to mechanical strain softening and strain history, namely the “Payne” and “Mullins” effects. The sensitivity of the complex permittivity to such effects is several orders of magnitude greater than in corresponding, traditional mechanical tests. In addition, we demonstrate for the first time that i...

The role of filler particles in defining local changes to the dynamics of elastomer polymers – specifically in relation to the reinforcement of commercial elastomer systems – is as yet incompletely resolved. This work examines the glass transition of filled, crosslinked natural rubber in relation to filler reinforcement mechanisms using a variety of complimentary experimental techniques. Carbon black and precipitated silica filler particles with a wide range of surface areas, structures and surface activities are used as the reinforcing phase. No effect of the filler particles on the calorimetric glass transition is observed in terms of shifting, broadening or transition strength. Dielectric spectroscopy measurements show that the polymer relaxation times of the filled rubbers in the glass-to-rubber transition zone remain essentially equivalent to that of the corresponding unfilled material. Dynamic mechanical analysis demonstrates that the storage moduli of the filled elastomers are significantly amplified on the rubbery side of the glass transition. Elastic stiffening mechanisms are discussed in the context of contributions from filler networking. The reason for a distinct lack of evidence for filler-induced polymer modification may be due to the nature of polymer confinement associated with the imperfect dispersion state of the fillers in the sample and the fact that the fillers themselves are formed from aggregated primary particles rather than being true nanoparticulates.