Viscosity, Morphology, and Thermomechanical Performance of Attapulgite-Reinforced Bio-Based Polyurethane 
Asphalt Composites

Yang, Haocheng; Cao, Suzhou; Cui, Xinpeng; Xi, Zhonghua; Cai, Jun; Yuan, Zuanru; Zhang, Junsheng; Xie, Hongfeng

doi:10.3390/polym17152045

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Open AccessArticle

Viscosity, Morphology, and Thermomechanical Performance of Attapulgite-Reinforced Bio-Based Polyurethane Asphalt Composites

by

Haocheng Yang

¹,

Suzhou Cao

¹,

Xinpeng Cui

¹,

Zhonghua Xi

²,

Jun Cai

³,

Zuanru Yuan

⁴,

Junsheng Zhang

^1,* and

Hongfeng Xie

^1,*

¹

MOE Key Laboratory of High Performance Polymer Materials and Technology, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China

²

Experimental Chemistry Teaching Center, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China

³

Public Instrument Center, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China

⁴

Modern Analysis Center, Nanjing University, Nanjing 210023, China

^*

Authors to whom correspondence should be addressed.

Polymers 2025, 17(15), 2045; https://doi.org/10.3390/polym17152045 (registering DOI)

Submission received: 27 June 2025 / Accepted: 24 July 2025 / Published: 26 July 2025

(This article belongs to the Special Issue Mechanical and Dynamic Characterization of Polymeric Composites, 3rd Edition)

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Abstract

Bio-based polyurethane asphalt binder (PUAB) derived from castor oil (CO) is environmentally friendly and exhibits extended allowable construction time. However, CO imparts inherently poor mechanical performance to bio-based PUAB. To address this limitation, attapulgite (ATT) with fibrous nanostructures was incorporated. The effects of ATT on bio-based PUAB were systematically investigated, including cure kinetics, rotational viscosity (RV) evolution, phase-separation microstructures, dynamic mechanical properties, thermal stability, and mechanical performance. Experimental characterization employed Fourier transform infrared spectroscopy, Brookfield viscometry, laser scanning confocal microscopy, dynamic mechanical analysis, thermogravimetry, and tensile testing. ATT incorporation accelerated the polyaddition reaction conversion between isocyanate groups in polyurethane (PU) and hydroxyl groups in ATT. Paradoxically, it reduced RV during curing, prolonging allowable construction time proportionally with clay content. Additionally, ATT’s compatibilizing effect decreased bitumen particle size in PUAB, with scaling proportionally with clay loading. While enhancing thermal stability, ATT lowered the glass transition temperature and damping properties. Crucially, 1 wt% ATT increased tensile strength by 71% and toughness by 62%, while maintaining high elongation at break (>400%). The cost-effectiveness and significant reinforcement capability of ATT make it a promising candidate for producing high-performance bio-based PUAB composites.

Keywords: polyurethane asphalt; bio-based polyurethane; phase separation; cure kinetics; glass transition temperature

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MDPI and ACS Style

Yang, H.; Cao, S.; Cui, X.; Xi, Z.; Cai, J.; Yuan, Z.; Zhang, J.; Xie, H. Viscosity, Morphology, and Thermomechanical Performance of Attapulgite-Reinforced Bio-Based Polyurethane Asphalt Composites. Polymers 2025, 17, 2045. https://doi.org/10.3390/polym17152045

AMA Style

Yang H, Cao S, Cui X, Xi Z, Cai J, Yuan Z, Zhang J, Xie H. Viscosity, Morphology, and Thermomechanical Performance of Attapulgite-Reinforced Bio-Based Polyurethane Asphalt Composites. Polymers. 2025; 17(15):2045. https://doi.org/10.3390/polym17152045

Chicago/Turabian Style

Yang, Haocheng, Suzhou Cao, Xinpeng Cui, Zhonghua Xi, Jun Cai, Zuanru Yuan, Junsheng Zhang, and Hongfeng Xie. 2025. "Viscosity, Morphology, and Thermomechanical Performance of Attapulgite-Reinforced Bio-Based Polyurethane Asphalt Composites" Polymers 17, no. 15: 2045. https://doi.org/10.3390/polym17152045

APA Style

Yang, H., Cao, S., Cui, X., Xi, Z., Cai, J., Yuan, Z., Zhang, J., & Xie, H. (2025). Viscosity, Morphology, and Thermomechanical Performance of Attapulgite-Reinforced Bio-Based Polyurethane Asphalt Composites. Polymers, 17(15), 2045. https://doi.org/10.3390/polym17152045

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Viscosity, Morphology, and Thermomechanical Performance of Attapulgite-Reinforced Bio-Based Polyurethane Asphalt Composites

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