Investigation of the Thermal Degradation of SBS Polymer in Long-Term Aged Asphalt Binder Using Confocal Laser Scanning Microscopy (CLSM)

Abstract

Styrene–butadiene–styrene (SBS) polymer is extensively employed for asphalt pavement construction, and its degradation significantly damages the durability of asphalt concrete. However, the effect of aging protocols on the degradation of SBS polymer in asphalt binder has not been thoroughly investigated. In this study, confocal laser scanning microscopy (CLSM) was applied to characterize the change in morphology with SBS polymer degradation. Various aging protocols were considered, including accelerated aging processes in laboratory- and field-aged samples from three highway sections with different in-service periods. Scanned images of the polymer phase in the 2D plane at different depths were processed and further reconstructed in three dimensions. Furthermore, the three-dimensional polymer morphology indices derived from the semi-quantitative analysis of the images were correlated with the rheological indices. The results show that the polymer particles change from a relatively large ellipsoidal shape to a relatively small spherical shape as aging proceeds. The increase in aging temperature appears to accelerate the degradation of the polymer at the same rheological level. The effect of the laboratory aging method on the polymer was more pronounced during the early stages of aging compared to that in the field aging process.

The Aging of Polymers under Electromagnetic Radiation

“…Adding four complexes to the polymer and exposing the polymer to 300 h of UV radiation enhanced the photostability of the films [ 160 ]. For the degradation of the SPS polymer, Ding et al’s [ 161 ] experimental research used confocal laser scanning microscopy (CLSM) to characterize morphological changes after exposure to UV radiation. The study considered various protocols of aging, including accelerated laboratory degradation and aged samples gathered from the field with varying in-service periods [ 161 ].…”

“…For the degradation of the SPS polymer, Ding et al’s [ 161 ] experimental research used confocal laser scanning microscopy (CLSM) to characterize morphological changes after exposure to UV radiation. The study considered various protocols of aging, including accelerated laboratory degradation and aged samples gathered from the field with varying in-service periods [ 161 ]. The study then processed the polymer’s scanned images in the 2D phase at various depths, followed by 3D reconstructions, which helped derive polymer morphology indices.…”

“…The study then processed the polymer’s scanned images in the 2D phase at various depths, followed by 3D reconstructions, which helped derive polymer morphology indices. The findings from the study disclosed that as aging progresses, polymer particles transform from considerably large ellipsoidal shapes to smaller spherical shapes [ 161 ]. Increasing aging temperatures resulted in accelerated polymer acceleration at given rheological levels [ 161 ].…”

“…The findings from the study disclosed that as aging progresses, polymer particles transform from considerably large ellipsoidal shapes to smaller spherical shapes [ 161 ]. Increasing aging temperatures resulted in accelerated polymer acceleration at given rheological levels [ 161 ]. Moreover, melt viscoelastic assessment studies have also been conducted to determine the aging properties of poly(lactic acid) by burying polymer films in composts at 58 °C to determine their biodegradability and assess their molecular evolution [ 162 ].…”

Durability of Polymer-Modified Asphalt Mixture with Wasted Tire Powder and Epoxy Resin under Tropical Climate Curing Conditions

“…One promising approach is the use of polymer-modified asphalt binders [10,24,25], which can enhance the mechanical properties of the mixture, such as stiffness, strength, and resistance to deformation [26,27]. The addition of crumb rubber powder from waste car tires and epoxy resin has also been investigated to further improve the properties of the mixture [25,28,29].…”