Large-scale dispersion of the hierarchical (1D, 2D and 3D) carbonaceous nanofillers in thermoplastic polyurethane through supramolecular self-assembly and extrusion

ABSTRACT

The hierarchical carbonaceous nanofillers viz. carboxylated multiwalled carbon nanotube (MWCNT-COOH as 1D), hydroxylated few-layer graphene (FLG-OH as 2D), and hybrid 3D i.e., MWCNT-COOH immobilized into FLG-OH were dispersed into segmented thermoplastic polyurethane (TPU) by twin-screw extrusion (TSE). The concentration of nanofillers was varied as 0.25, 0.5, 1.0, 2.0 and 5 wt%. To increase the level of dispersion, hybrid 3D nanofillers were also incorporated into TPU by producing cellular structures through supramolecular self-assembly route (SSAR). The cellular structure in which the nanofillers were found to be uniformly dispersed was then compounded by TSE technique. The large-scale uniform dispersion was observed at higher loading (2 wt%) by SSAR followed by TSE when compared with direct TSE. Uniform dispersion was found at 1 wt% loading by direct TSE. PU nanocomposite film reinforced with 2 wt% hybrid 3D nanofillers showed good gas barrier property with ~63% reduction of helium gas permeability to 472 cm³/m²/day from 1287 cm³/m²/day of neat PU film.

GRAPHICAL ABSTRACT

KEYWORDS:

• Polyurethane
• carbonaceous nanofillers
• extrusion
• supramolecular self-assembly
• dispersion

Acknowledgements

The authors are thankful to the Director, DMSRDE, Defence Research and Development Organization for support, encouragement, and giving permission to publish the article. The authors are very grateful to Dr. Bapan Adak (former PhD Scholar, IIT Delhi) for helping to prepare the samples by TSE and film preparation by compression molding; Mr. Uttam Saha (for ATR-FTIR), Mr. Sanjay Kanojia (for TGA), Mr. Abhisar Hudda, Mr. Shudhanshu Singh (for XRD), and Ms. Ratna Singh (for helping to prepare the manuscript) from DMSRDE, Kanpur (DRDO). The authors extend their gratitude to Mr. Vipul Garg (B.Tech student, IIT Delhi) for his help with cryo-ultramicrotome. The authors are also thankful to ADRDE, Agra (DRDO), for providing the facility for helium gas permeability testing. The authors are very thankful to the Central Research Facility (CRF), IIT Delhi, India (for providing TEM facility), and the Nano Research Centre (NRC), IIT Kanpur, India (for providing FE-SEM facility). The authors are grateful to the Director, DMSRDE, DRDO, Kanpur, for help, financial support, and granting permission to publish their experimental findings.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/09276440.2023.2269344