Rheological and Aging Properties of Vegetable Oil-Based Polyurethane (V-PU) Modified Asphalt

Current asphalt modification methods often rely on non-renewable resources and lack detailed understanding of aging behavior. Prior research has shown that synthetic polymers can enhance asphalt properties, but their environmental impact remains a concern. This gap motivated the exploration of renewable alternatives. Vegetable oil-based materials have been proposed as sustainable options, but their performance under aging conditions is not well established. It was already known that polyurethanes can improve mechanical properties, but their application in asphalt modification is still under investigation. No prior work had resolved how the molecular structure of polyurethanes affects asphalt aging. The need for environmentally friendly and durable road materials remains unmet. This study addresses the lack of knowledge on how vegetable oil-based polyurethanes influence asphalt behavior. The research fills a critical need in sustainable infrastructure development.

This study aimed to evaluate how vegetable oil-based polyurethane modifies asphalt properties. The researchers focused on rheological and aging characteristics, which are essential for road performance. They wanted to determine if V-PU could replace traditional modifiers while maintaining durability. The motivation came from the need for sustainable materials in civil engineering. The team also sought to understand how V-PU interacts with asphalt during aging. They hypothesized that the cross-linking behavior of V-PU would improve mechanical resistance. The study tested different V-PU concentrations to find the optimal formulation. The goal was to provide a renewable alternative with performance comparable to conventional methods.

The researchers synthesized V-PU from castor oil and liquefied MDI-100LL. They prepared asphalt samples with 10-40 wt% V-PU content. Temperature classification tests were conducted to assess thermal behavior. Multiple stress creep recovery (MSCR) tests measured deformation resistance. Linear amplitude scanning (LAS) evaluated viscoelastic properties. Fourier-transform infrared (FTIR) spectroscopy analyzed chemical changes. Gel permeation chromatography (GPC) tracked molecular weight shifts. Fluorescence microscopy visualized V-PU agglomeration. The team examined how aging affects the molecular structure and performance of modified asphalt. These methods provided insights into the interaction between V-PU and asphalt.

The modulus of V-PU modified asphalt increased with higher concentrations. The creep recovery rate (R) and yield stress also rose with V-PU content. The highest performance was observed at 30 wt% V-PU. The phase angle and Jnr decreased with increasing V-PU, indicating better recovery. The high-temperature grade improved by four levels with 30 wt% V-PU. FTIR showed chemical interactions between V-PU and asphalt components. GPC revealed a significant increase in molecular weight after aging. Fluorescence microscopy confirmed V-PU agglomeration. The cross-linked network formed by V-PU improved mechanical resistance. These results suggest that V-PU enhances asphalt durability and aging resistance.

The study found that V-PU improves asphalt rheological and aging properties. The researchers propose that the cross-linked network enhances mechanical resistance. The 30 wt% V-PU sample showed the best performance. The phase inversion observed supports the effectiveness of this concentration. The authors suggest that the intramolecular cementation reaction plays a key role. The aging process leads to V-PU agglomeration and increased molecular weight. These findings indicate that V-PU is a viable renewable modifier. The study contributes to the development of sustainable road materials.