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Bisphenol A epoxy resin cured with a mixture of dimerized and trimerized fatty acids is the first epoxy vitrimer and has been extensively studied. However, the cure behavior and thermal and mechanical properties of this epoxy vitrimer depend on the epoxy/acid stoichiometry. To address these issues, epoxy vitrimers with three epoxy/acid stoichiometries (9:11, 1:1 and 11:9) were prepared and recycled four times. Differential scanning calorimetry (DSC) was used to study the cure behavior of the original epoxy vitrimers. The dynamic mechanical properties and mechanical performance of the original and recycled epoxy vitrimers were investigated by using dynamic mechanical analysis (DMA) and a universal testing machine. Furthermore, the reaction mechanism of epoxy vitrimer with different epoxy/acid stoichiometry was interpreted. With an increase in the epoxy/acid ratio, the reaction rate, swelling ratio, glass transition temperature and mechanical properties of the original epoxy vitrimers decreased, whereas the gel content increased. The recycling decreased the swelling ratio and elongation at break of the original epoxy vitrimers. Moreover, the elongation at break of the recycled epoxy vitrimers decreased with the epoxy/acid ratio at the same recycling time. However, the gel content, tensile strength and toughness of the original epoxy vitrimers increased after the recycling. The mechanical properties of epoxy vitrimers can be tuned with the variation in the epoxy/acid stoichiometry.

This paper deals with the impact of polymer loading on the microstructure, viscosity, thermal properties and mechanical performance of recycled polyethylene (rPE) modified epoxy asphalt binder. With this aim, rPE was used as a modifier to improve the toughness of a hot-mix epoxy asphalt binder. rPE particles were found to be highly swollen by the asphalt. Double phase separation was observed in rPE modified epoxy asphalt binders: asphalts dispersed in the continuous epoxy phase and rPE particles distributed in the discontinuous asphalt phase. The viscosity of epoxy asphalt binders increased with more rPE contents but the allowable construction time for pavement remained long. Results revealed that the thermal stability of epoxy asphalt binders was slightly improved with the addition of rPE. Furthermore, rPE lowered the glass transition temperature and increased the storage modulus at the rubbery state. All rPE modified epoxy asphalt binders performed better damping behaviours. In addition, at low rPE concentrations, the mechanical properties of epoxy asphalt binders were improved while at rPE loading higher than 2%, the results were opposite. [ABSTRACT FROM AUTHOR]

Asphaltenes tend to aggregate to nanoparticles or clusters in crude oil and solvents over a wide concentration and temperature range. In the present paper, asphaltenes extracted from the base asphalt was used as a filler to introduce into epoxy resin. The microstructure and evolution of asphaltenes aggregation in the epoxy resin were observed using laser scanning confocal microscopy. Furthermore, the effect of asphaltenes on the viscosity, dynamic mechanical behavior, thermostability, mechanical properties of epoxy resin was evaluated by Brookfield rotational viscometer, dynamic mechanical analysis, thermogravimetric analysis and universal testing machine. The presence of asphaltenes increased the viscosity of the neat epoxy during all stages of cure reaction. The viscosity of epoxy/asphaltenes composites increased with the filler concentration. Fractal asphaltenes aggregation formed in the composites with 1 mass% asphaltenes. Network microstructures of asphaltenes aggregation appeared in the epoxy phase with a further increase of asphaltenes content. Moreover, the increase of asphaltenes loading resulted in denser network microstructures in the epoxy matrix. Aggregation evolution revealed that asphaltenes particles redispersed evenly in the epoxy resin in the form of some aggregates at the beginning of curing. During the cure reaction of epoxy, asphaltenes aggregates started to agglomerate and grow to network microstructures. The presence of asphaltenes led to the enhancement of the storage modulus of the neat epoxy at the rubbery stage. The glass transition temperature (Tg) of the epoxy composites slightly increased with the increase of asphaltenes loading. The epoxy composite with 5 mass% asphaltenes had higher Tg than the neat epoxy. The inclusion of asphaltenes had a negligible effect on the damping properties and thermal stability of the neat epoxy. The aggregation and heterogeneous dispersion of asphaltenes resulted in the decrease of the tensile strength and elongation at break of the neat epoxy. However, the inclusion of asphaltenes significantly enhanced Young's modulus of the neat epoxy. Young's modulus of the neat epoxy was increased by more than fourfold with the addition of 5 mass% asphaltenes. [ABSTRACT FROM AUTHOR]

Sasobit has been widely applied as warm-mix asphalt (WMA) additive in an environment friendly and energy saving pavement construction. Epoxy asphalt (EA) has been extensively used on the pavement of steel bridge decks. In the present paper, Sasobit was introduced into warm-mix epoxy asphalt binder (WEAB) to prepare Sasobit modified WEAB. The effect of Sasobit on the viscosity, thermal, damping and mechanical properties and morphology of the neat WEAB were investigated using various characterisation techniques. Sasobit significantly lowered the viscosity of the neat WEAB and prolonged the operational lifetime for mixture pavement. Sasobit lowered the glass transition temperature of the neat WEAB. Sasobit slightly decreases the damping properties and thermal stability of the neat WEAB. However, Sasobit increased the tensile strength of the neat WEAB. The crystalline network structures of Sasobit formed in asphalts were clearly observed. The lamellar crystalline structure of Sasobit turned to gel-like structure in curly ribbon shape with an increase of the WMA additive contents. Reaction-induced phase separation occurred in the neat WEAB and Sasobit modified WEABs. No crystalline network structures of Sasobit were observed in the dispersed asphalt phase of the modified WEABs. Sasobit decreased the size of asphalt particles in the continuous epoxy phase. [ABSTRACT FROM AUTHOR]

Epoxy asphalt bond coat (EABC) has been widely used as a bonding layer in the construction of orthotropic steel deck bridges. To withstand the vibration of the steel deck, EABC needs to have strong bonding strength. In present article, sodium montmorillonite (Mt) was used to reinforce the neat EABC. The morphology and properties of EABC/Mt nanocomposites were characterized by scanning electron microscopy, X‐ray diffraction, Brookfield rotational viscometer, dynamic mechanical analysis, thermogravimetric analysis, automatic adhesion tester, and universal testing machine. No intercalation structure formed in the EABC/Mt nanocomposites. Mt dispersed uniformly in the EABC matrix. The inclusion of Mt increased the viscosity of the neat EABC in the initial stage of chemical reaction. Whereas, in the later curing stage, the viscosity of the neat EABC was higher than those of EABC/Mt nanocomposites. The presence of Mt slightly reduced the glass transition temperature of the neat EABC. The damping performance of the neat EABC was improved with the inclusion of 1 wt% Mt. Mt had a marginal effect on the thermal stability of the neat EABC. The incorporation of Mt significantly enhanced the mechanical properties of the neat EABC. The tensile strength and toughness of the neat EABC increased by 30% and 26%, respectively, with the inclusion of 3 wt% Mt. The existence of Mt greatly enhanced adhesion strength of the neat EABC. The lap‐shear adhesion strength and pull‐off adhesion strength of the EABC nanocomposite with 5 wt% Mt were 33% and 29% higher than those of the neat EABC. [ABSTRACT FROM AUTHOR]

Highlights • Halogen-free flame retarded cold-mix epoxy asphalt binder (CEAB) has been developed. • The flame retardancy of the neat CEAB is significantly increased by halogen-free flame retardant. • The addition of halogen-free flame retardants improves the glass transition temperature, thermal stability and tensile strength of the neat CEAB. Abstract Fire safety of asphalt mixtures in highway tunnels has become a problem of great concerns since asphalt and polymer modified asphalt binders are quite flammable and tend to release poisonous gases and smoke while burning. Therefore, flame retardants are incorporated into asphalt binder to improve the fire retardancy of asphalt mixtures. In this paper, aluminum trihydroxide (ATH) and zinc borate (ZB) were used as halogen-free flame retardants to prepare flame retarded cold-mix epoxy asphalt binders (CEABs). The addition of halogen-free flame retardants increased flame retardancy of the neat CEAB. In addition, ATH-ZB retarded CEAB had higher limited oxygen index (LOI) than single ATH and ZB retarded CEABs at the same content. The presence of halogen-free flame retardants increased the viscosity of the neat CEAB. The viscosity of ATH/ZB retarded CEAB was lower than that of ATH retarded CEAB at a specific content. The incorporation of halogen-free flame retardants enhanced the glass transition temperature of the neat CEAB. Thermal stability of the neat CEAB was improved by the halogen-free flame retardants. ATH/ZB retarded CEAB had better thermal stability than ATH retarded CEAB at the same content. The addition of halogen-free flame retardants increased the tensile strength of the neat CEAB. Uniform dispersion of halogen-free flame retardants in CEABs was observed. [ABSTRACT FROM AUTHOR]

As one of polymer modified asphalts (PMAs), epoxy asphalt (EA) has been extensively used in the pavement of steel bridge deck due to its excellent performances. Ethylene vinyl acetate copolymer (EVA) is one of most used polymer modifiers in PMAs. EA/EVA blends were prepared with the addition of EVA in asphalts. The effects of EVA on the morphology evolution of EA were investigated by laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM). Furthermore, the rotational viscosity, thermal stability and mechanical properties of EA/EVA blends were studied. LSCM observed that epoxy resin was the continuous phase and EVA-asphalt was the disperse phase in EA/EVA blends. The presence of epoxy crosslinking network destroyed the physical interaction between EVA and asphalts. Both LSCM and SEM observations found that smaller and well-distributed EVA-asphalt particles formed in EA/EVA blends with lower EVA loadings. However, EVA-asphalt particles distributed inhomogeneously in the blends with higher EVA loadings. The addition of EVA increased the viscosity of the neat EA. Moreover, the presence of EVA improved both thermal stability and mechanical properties of the neat EA. [ABSTRACT FROM AUTHOR]

[Display omitted] • Eco-friendly fire-retarded warm-mix epoxy asphalt binders (WEABs) have been developed. • RPFR of significantly improved the fire retardancy of the pure WEAB. • RPFR hinders WEAB's cure reaction and extends the allowable construction time of WEAB mixtures. • RPFR improves the glass transition temperature and thermal stability of the pure WEAB. • Double phase separation forms in RPFR modified WEABs. Epoxy asphalt binder is flammable and plenty of fumes are produced during its high-temperature pavements in tunnels. To improve fire retardancy and reduce asphalt fumes, eco-friendly flame-retarded warm-mix epoxy asphalt binders (WEABs) for road tunnel pavements were developed by incorporation of reactive polymeric flame retardant (RPFR), which was composed of a reactive polymeric brominated epoxy oligomer (BEO) and antimony oxide. The influence of RPRF on flame retardancy, rotational viscosity, microstructures, thermal properties and mechanical performance of the pure WEAB was investigated using various techniques: oxygen index instrument, Brookfield viscometer, confocal microscope, differential scanning calorimeter, thermogravimetric analyzer and universal testing machine. The presence of RPFR significantly improved the limited oxygen index (LOI) of the pure WEAB. The LOI of RPFR modified WEABs increased in the flame retardant loading. The reaction of epoxide groups of RPFR with the curing agents of epoxy asphalt reduced the viscosity of the pure WEAB and extended the allowable construction time of the WEAB mixture. The inclusion of RPFR increased the glass transition temperature (T g) of the pure WEAB. For modified WEABs, the T g increased in the RPFR loading. RPFR reacted into the epoxy asphalt backbone through the reaction between epoxy groups and curing agents. The incorporation of RPFR improved the thermal stability of the pure WEAB. The addition of 8 wt% RPFR increased the tensile strength of the pure WEAB, while the inclusion of RPFR slightly decreased the break elongation of the pure WEAB. Double phase separation occurred in RPFR modified WEAB: the main phase separation included the continuous epoxy phase and the discontinuous asphalt domains, in which the secondary phase separation formed with asphalt as the continuous phase and spherical BEO domains as the discontinuous phase. The particle size of BEO domains decreased with the increase of the RPFR loading. [ABSTRACT FROM AUTHOR]

• Phase separation of ESBA disrupts the original dispersion of SBS in the asphalt. • The size of SBS domains in ESBAs increases in the SBS loading. • ESBA's viscosity increases in the SBS loading. • The thermal stability of ESBAs enhances with the increase of SBS loading. • The neat EA's elongation at break increases by 56% with the addition of 3 wt% SBS. Both styrene–butadiene-styrene copolymer (SBS) and epoxy resin have been widely applied in the asphalt modification. The influence of SBS concentration on the morphology, viscosity, thermal stability, glass transition temperature (T g), damping performance and mechanical behaviors of the neat EA binder was studied. Double phase separation occurred in the epoxy SBS modified asphalt (ESBA): main phase separation between epoxy and the SBS modified asphalt (SBA) and secondary phase separation between asphalt and SBS. The occurrence of phase separation in the ESBA disrupted the original dispersion of SBS particles in SBA and resulted in the redistribution of SBS in the form of smaller spherical particles. The inclusion of SBS increased the viscosity of the neat EA. Furthermore, the viscosity of ESBAs increased with the SBS content. ESBAs had as long as 150-min construction time for the mixture pavement. The presence of SBS improved the thermostability of the neat EA. In terms of ESBAs, the thermostability increased with the SBS content. The addition of SBS lowered the T g of the neat EA when the SBS content was lower than 4 wt%. The T g of ESBAs increased with the SBS content. The incorporation of SBS significantly enhanced the damping behaviors of the neat EA. The tensile strength of the neat EA was improved with the addition of 2 wt% SBS. The inclusion of SBS improved the elongation at break and the toughness of the neat EA when the SBS loading was greater than 1 wt%. [ABSTRACT FROM AUTHOR]

• Core-shell rubber (CSR) nanoparticle toughened epoxy asphalt (EA) has been developed. • The toughness of the pure EA increases by 2-fold with only addition of 1 wt% CSR. • The shell of CSR is broken and the core of CSR swells in the EA. • Newly micro-scale CSR phase uniformly disperses in the epoxy phase of the EA. • CSR nanoparticles alters the mechanism of phase separation of the pure EA. Core-shell rubber (CSR) has been widely applied in the improvement of the toughness for the brittle epoxy resin. In this study, an epoxy asphalt (EA) binder has been toughened by the inclusion of CSR nanoparticles with approximately 100–200 nm in diameter. The incorporation of CSR nanoparticles significantly increased the viscosity of the pure EA during curing. Even with 5 wt% CSR, the EA blend exhibited extremely long operational lifetime (more than 2.5 h) for mixture pavements. The glassy shell of CSR nanoparticles was broken and the rubbery core of CSR nanoparticles swelled in the EA. New micro-scale CSR domains formed and uniformly dispersed in the epoxy phase of the cured EA. The inclusion of CSR nanoparticles altered the phase separation mechanism of the pure EA. The sea-island morphology of the pure EA took place through the nucleation and growth (NG) mechanism, while co-continuous microstructures in the EA blends with 3 wt% and 5 wt% CSR formed through the spinodal decomposition (SD) mechanism. Both sea-island and co-continuous microstructures via combined the NG and SD mechanisms were observed in the EA blend containing 1 wt% CSR. The glass transition temperature and thermal stability of the pure EA was improved by the inclusion of higher CSR loadings. The incorporation of CSR greatly enhanced the mechanical properties of the pure EA. In the case of 1 wt% CSR inclusion, 29% increase in the tensile strength, 60% improvement in the elongation at break and 2-fold increment in the toughness were obtained. [ABSTRACT FROM AUTHOR]

• Waste cooking oil (WCO) modified epoxy asphalt binder (EAB) has been developed. • WCO lowers the viscosity and thus extends the construction time of the neat EAB. • Phase inversion in WEAB occurs when 6 wt% WCO is added. • WCO improves the low-temperature performance of the neat EAB. • WCO enhances the damping properties and thermal stability of the neat EAB. Waste cooking oil (WCO) was used as a warm mix asphalt (WMA) additive to modify warm-mix asphalt binder (WEAB) with the expectation of lowering the viscosity and prolonging the construction time of the binder. The viscosity, phase separation, viscoelasticity, thermostability and mechanical properties of WCO modified WEABs were studied and compared with the neat WEAB. WCO significantly reduced the WEAB's viscosity and extended the construction time of the neat WEAB. Moreover, the reducing and prolonging effects increased with the WCO content. Phase-inverted microstructure and secondary phase separation formed in the modified WEAB with 6 wt% WCO. The inclusion of WCO improved the low-temperature performance of the neat WEAB. The damping behavior and thermostability of the neat WEAB were improved with the inclusion of WCO. The presence of WCO increased the elongation at break of the neat WEAB when the waste oil content was lower than 4 wt%. [ABSTRACT FROM AUTHOR]

• Brominated SBS (BrSBS) modified epoxy asphalt (EBrSA) binder has been developed. • The nucleophilic substitution reaction occurs between BrSBS and amine curing agent. • Phase inversion takes place in the EBrSAs with higher BrSBS contents. • The flame retardancy of the neat HEAB is significantly improved by BrSBS. • BrSBS greatly increases the glass transition temperature of the neat HEAB. Brominated styrene–butadienestyrene triblock copolymer (BrSBS) is a novel polymeric flame retardant (PolyFR), which is eco-friendly due to its huge molecule weight. In this paper, BrSBS was added into an epoxy asphalt binder (EAB) to enhance the flame resistance of EAB. The microstructure, viscosity, fire resistance, thermal stability, dynamic mechanical behaviors and mechanical properties of BrSBS modified EABs (EBrSAs) were studied. Double phase separation occurred in EBrSAs. BrSBS modified asphalt (BrSA)-rich phase co-continuously dispersed in the continuous epoxy matrix when BrSBS content was lower. However, phase-inverted morphology appeared when the BrSBS content was higher. In other words, the epoxy-rich phase dispersed in the continuous BrSA-rich phase. The amine curing agent reacted with BrSBS through a bimolecular nucleophilic substitution (S N 2) mechanism, resulting in the formation of epoxy/BrSBS interpenetrating polymer networks (IPNs). The incorporation of BrSBS greatly increased the viscosity of the neat EAB due to the nucleophilic substitution reaction between BrSBS and amine curing agent. BrSBS with lower loading significantly improved the flame retardancy of the neat EAB. BrSBS lowered the thermal stability, mechanical and damping behaviors of the neat EAB. However, the glass transition temperature (T g) of the neat EAB was notably enhanced with the inclusion of BrSBS. [ABSTRACT FROM AUTHOR]