Research

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20 pages, 5725 KiB

Open AccessArticle

Comprehensive Enhancement of Prepolymer-Based Flexible Polyurethane Foams’ Performance by Introduction of Cost-Effective Waste-Based Ground Tire Rubber Particles

by Wiktoria Żukowska, Paulina Kosmela, Paweł Wojtasz, Mariusz Szczepański, Adam Piasecki, Roman Barczewski, Mateusz Barczewski and Aleksander Hejna

Materials 2022, 15(16), 5728; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15165728 - 19 Aug 2022

Cited by 11 | Viewed by 2108

Abstract

Material innovations in polyurethane (PU) foams should ideally combine performance enhancement, environmental impact limitation, and cost reduction. These goals can be achieved by applying recycled or waste-based materials without broader industrial applications, implicating their low price. Herein, from 5 to 20 parts by [...] Read more.

Material innovations in polyurethane (PU) foams should ideally combine performance enhancement, environmental impact limitation, and cost reduction. These goals can be achieved by applying recycled or waste-based materials without broader industrial applications, implicating their low price. Herein, from 5 to 20 parts by weight of ground tire rubber (GTR) particles originated from the recycling of postconsumer car tires were incorporated into a flexible foamed PU matrix as a cost-effective waste-based filler. A two-step prepolymer method of foams manufacturing was applied to maximize the potential of applied formulation changes. The impact of the GTR content on the foams’ processing, chemical, and cellular structure, as well as static and dynamic mechanical properties, thermal stability, sound suppression ability, and thermal insulation performance, was investigated. The introduction of GTR caused a beneficial reduction in the average cell diameter, from 263.1 µm to 144.8–188.5 µm, implicating a 1.0–4.3% decrease in the thermal conductivity coefficient. Moreover, due to the excellent mechanical performance of the car tires—the primary application of GTR—the tensile performance of the foams was enhanced despite the disruption of the cellular structure resulting from the competitiveness between the hydroxyl groups of the applied polyols and on the surface of the GTR particles. The tensile strength and elongation at break were increased by 10 and 8% for 20 parts by weight GTR addition. Generally, the presented work indicates that GTR can be efficiently applied as a filler for flexible PU foams, which could simultaneously enhance their performance, reduce costs, and limit environmental impacts due to the application of waste-based material. Full article

(This article belongs to the Special Issue Current Developments in Polyurethane Materials for Different Applications)

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22 pages, 5823 KiB

Open AccessArticle

Viscoelastic Polyurethane Foams for Use as Auxiliary Materials in Orthopedics

by Dominik Grzęda, Grzegorz Węgrzyk, Milena Leszczyńska, Leonard Szczepkowski, Michał Gloc and Joanna Ryszkowska

Materials 2022, 15(1), 133; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15010133 - 24 Dec 2021

Cited by 8 | Viewed by 2637

Abstract

One of the essential factors in prostheses is their fitting. To assemble a prosthesis with the residual limb, so-called liners are used. Liners used currently are criticized by users for their lack of comfort, causing excessive sweating and skin irritation. The objective of [...] Read more.

One of the essential factors in prostheses is their fitting. To assemble a prosthesis with the residual limb, so-called liners are used. Liners used currently are criticized by users for their lack of comfort, causing excessive sweating and skin irritation. The objective of the work was to develop viscoelastic polyurethane foams for use in limb prostheses. As part of the work, foams were produced with different isocyanate indexes (0.6–0.9) and water content (1, 2 and 3 php). The produced foams were characterized by scanning electron microscopy, computer microtomography, infrared spectroscopy, thermogravimetry and differential scanning calorimetry. Measurements also included apparent density, recovery time, rebound elasticity, permanent deformation, compressive stress value and sweat absorption. The results were discussed in the context of modifying the foam recipe. The performance properties of the foams, such as recovery time, hardness, resilience and sweat absorption, indicate that foams that will be suitable for prosthetic applications are foams with a water content of 2 php produced with an isocyanate index of 0.8 and 0.9. Full article

(This article belongs to the Special Issue Current Developments in Polyurethane Materials for Different Applications)

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14 pages, 5901 KiB

Open AccessArticle

Fly Ash as an Eco-Friendly Filler for Rigid Polyurethane Foams Modification

by Monika Kuźnia, Anna Magiera, Beata Zygmunt-Kowalska, Katarzyna Kaczorek-Chrobak, Kinga Pielichowska, Piotr Szatkowski, Aleksandra Benko, Magdalena Ziąbka and Wojciech Jerzak

Materials 2021, 14(21), 6604; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14216604 - 02 Nov 2021

Cited by 23 | Viewed by 2512

Abstract

There is currently a growing demand for more effective thermal insulation materials with the best performance properties. This research paper presents the investigation results on the influence of two types of filler on the structure and properties of rigid polyurethane foam composites. Fly [...] Read more.

There is currently a growing demand for more effective thermal insulation materials with the best performance properties. This research paper presents the investigation results on the influence of two types of filler on the structure and properties of rigid polyurethane foam composites. Fly ash as a product of coal combustion in power plants and microspheres of 5, 10, 15, and 20 wt.%, were used as rigid polyurethane foams modifiers. The results of thermal analysis, mechanical properties testing, and cellular structure investigation performed for polyurethane composites show that the addition of fly ash, up to 10 wt.%, significantly improved the majority of the tested parameters. The use of up to 20 wt.% of microspheres improves the mechanical and thermal properties and thermal stability of rigid polyurethane foams. Full article

(This article belongs to the Special Issue Current Developments in Polyurethane Materials for Different Applications)

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14 pages, 11237 KiB

Open AccessArticle

Rigid Polyurethane Foams Modified with Biochar

by Katarzyna Uram, Maria Kurańska, Jacek Andrzejewski and Aleksander Prociak

Materials 2021, 14(19), 5616; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14195616 - 27 Sep 2021

Cited by 15 | Viewed by 2453

Abstract

This paper presents results of research on the preparation of biochar-modified rigid polyurethane foams that could be successfully used as thermal insulation materials. The biochar was introduced into polyurethane systems in an amount of up to 20 wt.%. As a result, foam cells [...] Read more.

This paper presents results of research on the preparation of biochar-modified rigid polyurethane foams that could be successfully used as thermal insulation materials. The biochar was introduced into polyurethane systems in an amount of up to 20 wt.%. As a result, foam cells became elongated in the direction of foam growth and their cross-sectional areas decreased. The filler-containing systems exhibited a reduction in their apparent densities of up to 20% compared to the unfilled system while maintaining a thermal conductivity of 25 mW/m·K. Biochar in rigid polyurethane foams improved their dimensional and thermal stability. Full article

(This article belongs to the Special Issue Current Developments in Polyurethane Materials for Different Applications)

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17 pages, 6659 KiB

Open AccessArticle

Effect of the Addition of Biobased Polyols on the Thermal Stability and Flame Retardancy of Polyurethane and Poly(urea)urethane Elastomers

by Kamila Mizera, Kamila Sałasińska, Joanna Ryszkowska, Maria Kurańska and Rafał Kozera

Materials 2021, 14(7), 1805; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14071805 - 06 Apr 2021

Cited by 10 | Viewed by 2118

Abstract

Due to the current trends in sustainable development and the reduction in the use of fossil fuels (Green Deal strategy and the circular economy), and thus, the increased interest of the polyurethane industry in polyols derived from renewable sources, it is important to [...] Read more.

Due to the current trends in sustainable development and the reduction in the use of fossil fuels (Green Deal strategy and the circular economy), and thus, the increased interest of the polyurethane industry in polyols derived from renewable sources, it is important to study the impact of these polyols on the flammability of new bioelastomers. The goal of this study was to check the influence of biobased polyols, such as tall oil (TO)-based polyols, soybean oil (SO)-based polyol, and rapeseed oil (RO)-based polyol, on the reduction in the burning and fume emissions of polyurethane and poly(urea)urethane elastomers (EPURs and EPUURs). The thermal stability of these materials was tested using thermogravimetric analysis (TGA). In turn, the flame retardancy and smoke emissions were checked using a cone calorimetry test. The released gases were identified using TGA coupled with Fourier transform infrared (FT-IR) spectroscopy (TGA/FT-IR). Moreover, the morphological and structural characteristics of the char residues were characterized using FT-IR and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The obtained data were compared to the results received for elastomers produced with petroleum substrates. The addition of biobased polyols led to a reduction in the burning as a result of the formation of char, especially RO polyol. Moreover, the TO and RO polyols increased the thermal stability of the elastomers. Full article

(This article belongs to the Special Issue Current Developments in Polyurethane Materials for Different Applications)

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18 pages, 2408 KiB

Open AccessArticle

Viscoelastic Polyurethane Foams for Use in Seals of Respiratory Protective Devices

by Małgorzata Okrasa, Milena Leszczyńska, Kamila Sałasińska, Leonard Szczepkowski, Paweł Kozikowski, Katarzyna Majchrzycka and Joanna Ryszkowska

Materials 2021, 14(7), 1600; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14071600 - 25 Mar 2021

Cited by 9 | Viewed by 2091

Abstract

A key factor in effective protection against airborne hazards, i.e., biological and nonbiological aerosols, vapors, and gases, is a good face fit of respiratory protective devices (RPDs). Equally important is the comfort of use, which may encourage or discourage users from donning RPDs. [...] Read more.

A key factor in effective protection against airborne hazards, i.e., biological and nonbiological aerosols, vapors, and gases, is a good face fit of respiratory protective devices (RPDs). Equally important is the comfort of use, which may encourage or discourage users from donning RPDs. The objective of the work was to develop viscoelastic polyurethane foams for use in RPD seals. The obtained foams were characterized using scanning electron microscopy, infrared spectroscopy, thermogravimetry, and differential scanning calorimetry. Measurements also involved gel fraction, apparent density, air permeability, elastic recovery time, compression set, rebound resilience, and sweat uptake. The results were discussed in the context of modifications to the foam formulation: the isocyanate index (I_NCO) in the range of 0.6–0.9 and the blowing agent content in the range of 1.2–3.0 php. FTIR analysis revealed a higher level of urea groups with increasing water content in the formulation. Higher I_NCO and water content levels also led to lower onset temperatures of thermal degradation and higher glass-transition temperatures of the soft phase. A decrease in apparent density and an increase in mean pore sizes of the foams with increasing I_NCO and water content levels was observed. Functional parameters (air permeability, elastic recovery time, compression set, rebound resilience, and sweat uptake) were also found to be satisfactory at lower I_NCO and water content levels. Full article

(This article belongs to the Special Issue Current Developments in Polyurethane Materials for Different Applications)

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22 pages, 6321 KiB

Open AccessArticle

Burning Behaviour of Rigid Polyurethane Foams with Histidine and Modified Graphene Oxide

by Kamila Sałasińska, Milena Leszczyńska, Maciej Celiński, Paweł Kozikowski, Krystian Kowiorski and Ludwika Lipińska

Materials 2021, 14(5), 1184; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14051184 - 03 Mar 2021

Cited by 20 | Viewed by 2219 | Correction

Abstract

Since rigid polyurethane (PU) foams are one of the most effective thermal insulation materials with widespread application, it is an urgent requirement to improve its fire retardancy and reduce the smoke emission. The current work assessed the fire behavior of PU foam with [...] Read more.

Since rigid polyurethane (PU) foams are one of the most effective thermal insulation materials with widespread application, it is an urgent requirement to improve its fire retardancy and reduce the smoke emission. The current work assessed the fire behavior of PU foam with non-halogen fire retardants system, containing histidine (H) and modified graphene oxide (GO_A). For investigated system, three loadings (10, 20, and 30 wt.%) were used. The Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis, cone calorimetry (CC) and smoke density chamber tests as well as pre- and post-burning morphological evaluation using scanning electron microscope (SEM) were performed. Moreover, TGA combined with FT-IR was conducted to determine the substances, which could be evolved during the thermal decomposition of the PU with fire retardant system. The results indicated a reduction in heat release rate (HRR), maximum average rate of heat emission (MAHRE), the total heat release (THR) as well as the total smoke release (TSR), and maximum specific optical density (Ds_max) compared to the polyurethane with commercial fire retardant, namely ammonium polyphosphate (APP). A significantly improvement, especially in smoke suppression, suggested that HGO_A system may be a candidate as a fire retardant to reduce the flammability of PU foams. Full article

(This article belongs to the Special Issue Current Developments in Polyurethane Materials for Different Applications)

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Review

Jump to: Research

27 pages, 5622 KiB

Open AccessReview

Recent Advances in Fabrication of Non-Isocyanate Polyurethane-Based Composite Materials

by Piotr Stachak, Izabela Łukaszewska, Edyta Hebda and Krzysztof Pielichowski

Materials 2021, 14(13), 3497; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14133497 - 23 Jun 2021

Cited by 51 | Viewed by 6865

Abstract

Polyurethanes (PUs) are a significant group of polymeric materials that, due to their outstanding mechanical, chemical, and physical properties, are used in a wide range of applications. Conventionally, PUs are obtained in polyaddition reactions between diisocyanates and polyols. Due to the toxicity of [...] Read more.

Polyurethanes (PUs) are a significant group of polymeric materials that, due to their outstanding mechanical, chemical, and physical properties, are used in a wide range of applications. Conventionally, PUs are obtained in polyaddition reactions between diisocyanates and polyols. Due to the toxicity of isocyanate raw materials and their synthesis method utilizing phosgene, new cleaner synthetic routes for polyurethanes without using isocyanates have attracted increasing attention in recent years. Among different attempts to replace the conventional process, polyaddition of cyclic carbonates (CCs) and polyfunctional amines seems to be the most promising way to obtain non-isocyanate polyurethanes (NIPUs) or, more precisely, polyhydroxyurethanes (PHUs), while primary and secondary –OH groups are being formed alongside urethane linkages. Such an approach eliminates hazardous chemical compounds from the synthesis and leads to the fabrication of polymeric materials with unique and tunable properties. The main advantages include better chemical, mechanical, and thermal resistance, and the process itself is invulnerable to moisture, which is an essential technological feature. NIPUs can be modified via copolymerization or used as matrices to fabricate polymer composites with different additives, similar to their conventional counterparts. Hence, non-isocyanate polyurethanes are a new class of environmentally friendly polymeric materials. Many papers on the matter above have been published, including both original research and extensive reviews. However, they do not provide collected information on NIPU composites fabrication and processing. Hence, this review describes the latest progress in non-isocyanate polyurethane synthesis, modification, and finally processing. While focusing primarily on the carbonate/amine route, methods of obtaining NIPU are described, and their properties are presented. Ways of incorporating various compounds into NIPU matrices are characterized by the role of PHU materials in copolymeric materials or as an additive. Finally, diverse processing methods of non-isocyanate polyurethanes are presented, including electrospinning or 3D printing. Full article

(This article belongs to the Special Issue Current Developments in Polyurethane Materials for Different Applications)

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