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Microstructural Characterization of Ball-Milled Biochar and Its Reinforcing Efficiency in Biobased Thermoplastic Polyurethane through Preferential Embedment in the Soft Segment

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide In this study, we investigated the reinforcement effects of biochar on a bio-based thermoplastic polyurethane (bio-TPU). The particle size of the biochar was reduced and controlled by using a planetary ball milling process under varying milling conditions. The structure and morphology of ball-milled biochar (BBC) were thoroughly characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Brunauer–Emmett–Teller (BET) analysis. Bio-TPU/BBC composites were fabricated via melt compounding. The BBC was found to be preferentially localized within the soft segment (SS) phase of the TPU, as indicated by enhanced crystallization of the SS and a shift in its glass transition temperature ( T g ) to higher values. Two-dimensional small-angle X-ray scattering (2D SAXS) analysis revealed an increase in interdomain spacing from 11.22 to 12.09 nm with increasing BBC content, further supporting the preferential localization of BBC within the soft segments. This preferential reinforcement of the SS by BBC led to simultaneous improvements in both ultimate tensile strength (up to 35 MPa) and elongation-at-break (up to 780%) at a filler loading of 2.5 wt %. However, further increasing the BBC content to 10 wt % resulted in a decrease in elongation-at-break and toughness. Notably, the preferential embedment of BBC also contributed to a plateau stress of 8 MPa, addressing a known limitation in TPU design. Additionally, a 512% increase in Young’s modulus (YM) and a 26 °C improvement in the temperature corresponding to a 50% mass loss have been observed at 10 wt % BBC-filled bio-TPU composite, demonstrating a significant enhancement in the YM and thermal stability.

Source: ACS Sustainable Resource Management

DOI: 10.1021/acssusresmgt.5c00225

Authors: Kunal Manna, Chaoying Wan, Jaipal Gupta, James J. C. Busfield, Biqiong Chen, Ton Peijs

Institutions: University of Warwick, Queen Mary University of London, Queen's University Belfast

Language: English

Topic: Polymer Science and Applications

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Responsible consumption and production

Open Access status: hybrid

Estimated APC paid: $4,500