Research

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9 pages, 5426 KiB

Open AccessArticle

Synthesis and Properties of Moisture-Cured Reactive Polyurethane Containing Castor Oil and Oxime Compounds

by Zheng-Ying Wu

Polymers 2020, 12(8), 1838; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12081838 - 17 Aug 2020

Cited by 9 | Viewed by 5204

Reactive polyurethane hot-melt resin (moisture-cured reactive polyurethane, PUR) could successfully be prepared from poly(tetramethylene ether) glycol (PTMG), castor oil and dimethylglyoxime (DMG) by one or two-stage synthesis. Fourier-transform infrared spectroscopy (FTIR) analysis showed that the synthesis resins belonged to NCO-capped castor oil-based polyurethane. [...] Read more.

Reactive polyurethane hot-melt resin (moisture-cured reactive polyurethane, PUR) could successfully be prepared from poly(tetramethylene ether) glycol (PTMG), castor oil and dimethylglyoxime (DMG) by one or two-stage synthesis. Fourier-transform infrared spectroscopy (FTIR) analysis showed that the synthesis resins belonged to NCO-capped castor oil-based polyurethane. The thermal behaviors of the cured PUR were analyzed by differential scanning calorimeter (DSC) and dynamic mechanical analyzer (DMA) instruments. The results showed that the cured resin provided remeltable properties under the dosages of 3 wt% DMG. Furthermore, the phenomenon could be proved by FTIR analysis according to the characteristic absorption peak of NCO groups after the cured resin was heated. Comparing different syntheses, the resin prepared by one-stage synthesis showed random distribution of DMG with PUR structure and that prepared by two-stage synthesis had distribution of DMG with branching structure in the prepolymer. The former obtained lower remeltable temperatures from 90 to 130 °C than the latter temperatures, which had temperatures above 125 °C. The tensile test showed that all of the PUR films exhibited typical tough behavior. Thus, the cured resin with DMG dosages of 3 wt% provided remeltable and mechanical properties at the same time. Overall, the crosslinking density and numbers of dynamic bonds should be kept in balance for preparation of remeltable PUR. Full article

(This article belongs to the Special Issue Dynamic Networks for Sustainable and Self-Healing Polymers)

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Review

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34 pages, 5384 KiB

Open AccessReview

The Versatility of Polymeric Materials as Self-Healing Agents for Various Types of Applications: A Review

by Nik Nur Farisha Nik Md Noordin Kahar, Azlin Fazlina Osman, Eid Alosime, Najihah Arsat, Nurul Aida Mohammad Azman, Agusril Syamsir, Zarina Itam and Zuratul Ain Abdul Hamid

Polymers 2021, 13(8), 1194; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13081194 - 07 Apr 2021

Cited by 44 | Viewed by 7129

Abstract

The versatility of polymeric materials as healing agents to prevent any structure failure and their ability to restore their initial mechanical properties has attracted interest from many researchers. Various applications of the self-healing polymeric materials are explored in this paper. The mechanism of [...] Read more.

The versatility of polymeric materials as healing agents to prevent any structure failure and their ability to restore their initial mechanical properties has attracted interest from many researchers. Various applications of the self-healing polymeric materials are explored in this paper. The mechanism of self-healing, which includes the extrinsic and intrinsic approaches for each of the applications, is examined. The extrinsic mechanism involves the introduction of external healing agents such as microcapsules and vascular networks into the system. Meanwhile, the intrinsic mechanism refers to the inherent reversibility of the molecular interaction of the polymer matrix, which is triggered by the external stimuli. Both self-healing mechanisms have shown a significant impact on the cracked properties of the damaged sites. This paper also presents the different types of self-healing polymeric materials applied in various applications, which include electronics, coating, aerospace, medicals, and construction fields. It is expected that this review gives a significantly broader idea of self-healing polymeric materials and their healing mechanisms in various types of applications. Full article

(This article belongs to the Special Issue Dynamic Networks for Sustainable and Self-Healing Polymers)

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30 pages, 2874 KiB

Open AccessReview

The Impact of Vitrimers on the Industry of the Future: Chemistry, Properties and Sustainable Forward-Looking Applications

by Walter Alabiso and Sandra Schlögl

Polymers 2020, 12(8), 1660; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12081660 - 26 Jul 2020

Cited by 111 | Viewed by 15889

Abstract

Thermosets are known to be very reliable polymeric materials for high-performance and light-weight applications, due to their retained dimensional stability, chemical inertia and rigidity over a broad range of temperatures. However, once fully cured, they cannot be easily reshaped or reprocessed, thus leaving [...] Read more.

Thermosets are known to be very reliable polymeric materials for high-performance and light-weight applications, due to their retained dimensional stability, chemical inertia and rigidity over a broad range of temperatures. However, once fully cured, they cannot be easily reshaped or reprocessed, thus leaving still unsolved the issues of recycling and the lack of technological flexibility. Vitrimers, introduced by Leibler et al. in 2011, are a valiant step in the direction of bridging the chasm between thermoplastics and thermosets. Owing to their dynamic covalent networks, they can retain mechanical stability and solvent resistance, but can also flow on demand upon heating. More generally, the family of Covalent Adaptable Networks (CANs) is gleaming with astounding potential, thanks to the huge variety of chemistries that may enable bond exchange. Arising from this signature feature, intriguing properties such as self-healing, recyclability and weldability may expand the horizons for thermosets in terms of improved life-span, sustainability and overall enhanced functionality and versatility. In this review, we present a comprehensive overview of the most promising studies featuring CANs and vitrimers specifically, with particular regard for their industrial applications. Investigations into composites and sustainable vitrimers from epoxy-based and elastomeric networks are covered in detail. Full article

(This article belongs to the Special Issue Dynamic Networks for Sustainable and Self-Healing Polymers)

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