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Kothari J, Iroh JO. Self-Healing Poly(urea formaldehyde) Microcapsules: Synthesis and Characterization. Polymers (Basel) 2023; 15:polym15071668. [PMID: 37050281 PMCID: PMC10096928 DOI: 10.3390/polym15071668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 03/22/2023] [Accepted: 03/22/2023] [Indexed: 03/30/2023] Open
Abstract
Smart coatings and smart polymers have been garnering great interest in recent times due to their novel characteristics, such as being self-restoring, self-cleaning, and self-healing. However, most self-healing materials have a low glass transition temperature (Tg) and are inadequate for the repair of advanced composites. Because of their low Tg, the conventional self-healing materials plasticize and weaken the composites. In this study, moderate to high temperature self-healing microcapsules, capable of healing and thus stopping crack propagation, are prepared. The microcapsules were prepared using a two-step process involving the synthesis of poly(urea formaldehyde) (PUF) prepolymer, followed by the encapsulation of hexamethylene diisocyanate (HDI) in an oil-in-water emulsion to form a crosslinked PUF shell. Diisocyanates are of particular interest as self-healing encapsulants because of their diversity of structure and fast rate of hydrolysis. Successful encapsulation was verified by Fourier transform infrared spectroscopy (FTIR) and optical microscopy. Thermogravimetric analysis (TGA) was used to characterize the thermal properties of microcapsules. The onset temperature for microcapsule degradation varied from 155 °C to 195 °C. Dynamic mechanical analysis (DMA) was used to determine the thermomechanical response of microcapsule/epoxy films. DMA showed that the glass transition temperature (Tg) of the epoxy/microcapsule composite was greater than the Tg for neat epoxy and varied between 34 and 65 °C. The TGA analysis of the epoxy/microcapsule composite shows that the thermal stability and char retention of the epoxy/microcapsule composite increased and the low temperature decomposition peak at 150 °C, associated with the microcapsule, disappeared after the DMA test, indicating the occurrence of a reaction between HDI and the epoxy to form a crosslinked polyurea network structure.
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Muzata TS, Gebrekrstos A, Orasugh JT, Ray SS. An overview of recent advances in polymer composites with improved
UV
‐shielding properties. J Appl Polym Sci 2023. [DOI: 10.1002/app.53693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Affiliation(s)
- Tanyaradzwa S. Muzata
- Department of Polymer Technology and Engineering Harare Institute of Technology Harare Zimbabwe
| | - Amanuel Gebrekrstos
- Department of Chemical Sciences University of Johannesburg Johannesburg South Africa
- Centre for Nanostructures and Advanced Materials DSI‐CSIR Nanotechnology Innovation Centre, Council for Scientific and Industrial Research Pretoria South Africa
| | - Jonathan Tersur Orasugh
- Department of Chemical Sciences University of Johannesburg Johannesburg South Africa
- Centre for Nanostructures and Advanced Materials DSI‐CSIR Nanotechnology Innovation Centre, Council for Scientific and Industrial Research Pretoria South Africa
| | - Suprakas Sinha Ray
- Department of Chemical Sciences University of Johannesburg Johannesburg South Africa
- Centre for Nanostructures and Advanced Materials DSI‐CSIR Nanotechnology Innovation Centre, Council for Scientific and Industrial Research Pretoria South Africa
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Gopinath S, Adarsh NN, Nair PR, Mathew S. Carbon nanofiber-reinforced shape memory polyurethanes based on HTPB/PTMG blend as anticorrosive coatings. POLYM-PLAST TECH MAT 2022. [DOI: 10.1080/25740881.2022.2129386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Sithara Gopinath
- Advanced Molecular Materials Research Centre (AMMRC), Mahatma Gandhi University, Kottayam, India
| | | | - P. Radhakrishnan Nair
- Advanced Molecular Materials Research Centre (AMMRC), Mahatma Gandhi University, Kottayam, India
| | - Suresh Mathew
- Advanced Molecular Materials Research Centre (AMMRC), Mahatma Gandhi University, Kottayam, India
- School of Chemical Sciences, Mahatma Gandhi University, Kottayam, India
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