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•The PU prepolymers can chemically react with the base asphalt.•The PU has superior high-temperature stability, adhesion strength, and durability to asphalt.•The anti-aging ...performance of PU sealants is always a great concern.•High-density PU foam injection has been implemented as an alternative to the conventional cement.•PU-bonded mixture can improve the performance and extend the service life of pavements.
In the past decades, Polyurethane (PU) as an emerging polymer material has been widely used to construct, repair, reinforce, and protect civil engineering infrastructures. Meanwhile, various PU-based materials are increasingly employed in pavement engineering for new construction and maintenance, due to their excellent physical and chemical properties. In this review paper, the synthesis method, chemical structure, and engineering properties of PU materials were first introduced briefly. Secondly, the practical applications of PU materials in pavement engineering at present were summarized, mainly including PU-modified asphalt, PU-bonded mixture, PU sealant, and PU foam injection. Finally, the potential economic benefits and environmental impacts of utilizing PU materials in pavement engineering were further discussed towards sustainability.
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Sustainable routes for the synthesis of polyurethanes with industrial applications are discussed in this article. Polyurethane is currently one of the most commonly used polymers ...worldwide for various applications such as rigid and flexible foams, coatings, elastomers, adhesives and sealants. However, isocyanate precursors are very harmful at each stages of the life cycle of the polymers. Hence, new synthesis routes for isocyanate-free polyurethanes are reported in literature, but most of them suffer from significant lacks that prevent any industrial application. This feature article focuses on the new challenges and new opportunities of these routes. A first part is dedicated to the market, the manufacture and the hazards of polyurethanes. In a second part, this article deals with the synthesis routes leading to non-isocyanate polyurethane. Hence, the advantages and limits of these routes are reported and discussed. Finally the outlooks for a future and industrial use of non-isocyanate polyurethane in industry are examined.
Synthesis of water dispersed bio-derived polyurethane with favorable transparency, chemical resistance, UV-aging, and biodegradation attributes.
•Water dispersed bio-derived transparent polyurethanes ...have been synthesized.•The polyurethanes have high weight-average and number-average molecular weights.•The polyurethanes have high elongation at break and good chemical resistivity.•The polyurethanes have proficient UV-aging capability and biodegradability.
The present work demonstrates the fabrication of water dispersed bio-derived transparent polyurethane (WBPU) using different bio-derived precursors including PEG-600, dimer acid, castor oil, and glycerol. Three different compositions of WBPU were prepared by varying the amount of 1, 4-butanediol (BD), isophorone diisocyanate (IPDI), and glycerol-dimer acid modified citric acid based polyol. Different techniques including FTIR, XRD, 1H NMR, and 13C NMR were conducted to sanguine the successful synthesis of the WBPUs. Moreover, specific gravity, mechanical property measurements as well as GPC, TGA, and DSC studies were performed to get detail idea about the physical, mechanical, and thermal properties of the as-synthesized WBPUs. DLS was executed to check the particle sizes and stabilities of the as-prepared WBPUs in the dispersion medium. The as-prepared WBPUs have high weight-average molecular weight (Mw, 33,260−41,660 g/mol) and number-average molecular weight (Mn, 31,579−37,803 g/mol). They have specific gravities of ∼1.19−1.32. All WBPUs showed good toughness (∼26.7–27.6 MJ/m3), very high elongation at break (∼2544−3027%), high impact resistances (∼9.42−10.33 kJ/m), proficient adhesive strengths (∼7.19−8.09 kPa for wood and ∼5.33−6.16 kPa for metal) and good chemical resistance in different media. Moreover, the as-prepared WBPU exhibits not only high UV-aging capability but also proficient biodegradability. The WBPUs were successfully prepared through a sustainable route and those can be utilized as surface coating material.
We designed and synthesized a colorless transparent glassy polyurethane assembled using low‐molecular‐weight oligomers carrying a large number of loosely packed weak hydrogen bonds (H‐bonds), which ...has a glass transition temperature (Tg) up to 36.8 °C and behaves unprecedentedly robust stiffness with a tensile Young's modulus of 1.56±0.03 GPa. Fast room‐temperature self‐healing was observed in this polymer network: the broken glassy polyurethane (GPU) specimen can recover to a tensile strength up 7.74±0.76 MPa after healing for as little as 10 min, which is prominent compared to reported room‐temperature self‐healing polymers. The high density of loose‐packed hydrogen bonds can reversibly dissociate/associate below Tg of GPU (that is secondary relaxation), which enables the reconfiguration of the damaged network in the fractured interfaces, despite the extremely slow diffusion dynamics of molecular chains under room temperature. This GPU shows potential application as an optical lens.
A glassy polyurethane (GPU) assembled by linear oligomers carrying abundant weak hydrogen bonds is presented. It is not only colorless, transparent, and stiff, but also shows fast room‐temperature self‐healing owing to the high mobility of the loosely packed hydrogen bonds in the glassy state. Molecular‐level events that occur in this process are established.
Evaluation of biological degradation of polyurethanes Magnin, Audrey; Pollet, Eric; Phalip, Vincent ...
Biotechnology advances,
March-April 2020, 2020 Mar - Apr, 2020-03-00, 20200301, 2020-03, Letnik:
39
Journal Article
Recenzirano
Odprti dostop
Polyurethanes (PU) are a family of versatile synthetic polymers intended for diverse applications. Biological degradation of PU is a blooming research domain as it contributes to the design of ...eco-friendly materials sensitive to biodegradation phenomena and the development of green recycling processes. In this field, an increasing number of studies deal with the discovery and characterization of enzymes and microorganisms able to degrade PU chains. The synthesis of short lifespan PU material sensitive to biological degradation is also of growing interest. Measurement of PU degradation can be performed by a wide range of analytical tools depending on the architecture of the materials and the biological entities. Recent developments of these analytical techniques allowed for a better understanding of the mechanisms involved in PU biodegradation. Here, we reviewed the evaluation of biological PU degradation, including the required analytics. Advantages, drawbacks, specific uses, and results of these analytics are largely discussed to provide a critical overview and support future studies.
Plastic waste in the environment is a significant threat due to its resistance to biological processes. Here we report the ability of fungal strains found on floating plastic debris to degrade ...plastics. In particular, we wanted to know which fungi grow on plastic debris floating in the shoreline, whether these fungi have the ability to degrade plastics, whether the plastic-degrading fungi can degrade other complex C-polymers such as lignin, and whether lignin-degraders vice versa can also break down plastics. Overall, more than a hundred fungal strains were isolated from plastic debris of the shoreline of Lake Zurich, Switzerland, and grouped morphologically. Representative strains of these groups were then selected and genetically identified, altogether twelve different fungal species and one species of Oomycota. The list of fungi included commonly occurring saprotrophic fungi but also some plant pathogens. These fungal strains were then used to test the ability to degrade polyethylene and polyurethane. The tests showed that none of the strains were able to degrade polyethylene. However, four strains were able to degrade polyurethane, the three litter-saprotrophic fungi Cladosporium cladosporioides, Xepiculopsis graminea, and Penicillium griseofulvum and the plant pathogen Leptosphaeria sp. A series of additional fungi with an origin other than from plastic debris were tested as well. Here, only the two litter-saprotrophic fungi Agaricus bisporus and Marasmius oreades showed the capability to degrade polyurethane. In contrast, wood-saprotrophic fungi and ectomycorrhizal fungi were unable to degrade polyurethane. Overall, it seems that in majority only a few litter-saprotrophic fungi, which possess a wide variety of enzymes, have the ability to degrade polyurethane. None of the fungi tested was able to degrade polyethylene.
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•State-of-the-art and advances regarding UV-curable waterborne polyurethanes synthesis.•UV-WPU coatings are becoming attractive due to increasingly rigorous environmental ...demands.•UV-WPU has wide application in industry and academia with great productivity and sustainability.•There is a huge diversity of possible formulations for UV-WPU synthesis.
Waterborne polyurethane coatings prepared by UV-induced photoreactions (UV-WPU) are becoming very attractive due to the increasingly stringent environmental demands. They were developed to replace solvent-based polyurethanes in the coatings of wood, paper, plastics, metal, and glass, mainly because of their good physicochemical, rheological, and optical properties. Several UV-WPU formulations have been tested over the years, making their research substantial. However, no valuable review of this literature, focusing on the significant influencing factors in UV-WPU's manufacture, is available to date. This work aims to answer specific questions about the state of these materials' art, such as: "which monomers have been used most in UV-WPU synthesis?", "what type of photo-initiator has promoted the most efficient curing of the material?", "what additives or particles have been tested for composite UV-WPUs?", "which applications have UV-WPUs been directed to?", "what adaptations and technologies have already been tested to overcome the challenges of the process?", among others. As a result of a systematized bibliographic search in four databases, considering the period from January 2000 to July 2020, a total of one hundred and thirty-eight distinct and relevant articles on UV-WPUs were found. From this study, we hope to present a scientific source on the current state-of-the-art of UV-WPU synthesis, providing new combinations of raw materials and intelligent solutions, thus making material and industrial engineers able to mitigate the inconveniences of the process.
The unique properties of self-healing materials hold great potential in the field of biomedical engineering. Although previous studies have focused on the design and synthesis of self-healing ...materials, their application in in vivo settings remains limited. Here, we design a series of biodegradable and biocompatible self-healing elastomers (SHEs) with tunable mechanical properties, and apply them to various disease models in vivo, in order to test their reparative potential in multiple tissues and at physiological conditions. We validate the effectiveness of SHEs as promising therapies for aortic aneurysm, nerve coaptation and bone immobilization in three animal models. The data presented here support the translation potential of SHEs in diverse settings, and pave the way for the development of self-healing materials in clinical contexts.
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