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Waterborne Polyurethanes for Electrical Applications
Published in Ram K. Gupta, Ajay Kumar Mishra, Eco-Friendly Waterborne Polyurethanes, 2022
V. Dhinakaran, P.M. Bupathi Ram, S. Narain Kumar, M. Tharun Kumar, K.P. Manoj Kumar, M. Varsha Shree
These techniques add to the advantages of fabrication and utilization of WPU materials. The recycling process of the materials requires physical treatment, and the other methods, thermochemical and chemical recycling methods, require chemical treatment to generate feedstock chemicals for industry. Also, during energy recovery, waste materials undergo partial or complete oxidation, which consequently produces electricity and gaseous fuels [14]. The fact that the by-products produced during the recycling process are also nonhazardous and can be disposed of with ease without causing damage to the environment. The major recycling and energy regeneration techniques of PUs are chemical, mechanical, and thermochemical recycling. The recycling of WPU foams can be done by regrinding them into powder that can be used for multiple purposes. The processes used for this purpose include the following:Compression mouldingAdhesive pressingFlexible foam bonding
Contemporary Machining Processes for New Materials
Published in E. S. Gevorkyan, M. Rucki, V. P. Nerubatskyi, W. Żurowski, Z. Siemiątkowski, D. Morozow, A. G. Kharatyan, Remanufacturing and Advanced Machining Processes for New Materials and Components, 2022
E. S. Gevorkyan, M. Rucki, V. P. Nerubatskyi, W. Żurowski, Z. Siemiątkowski, D. Morozow, A. G. Kharatyan
Technology of the foam molding has been known for more than 40 years, but it is continuously improved and modified. Some injection molding technologies facilitate more sustainable production, while others allow the production of components with new structures and properties, but foam injection molding offers the potential to combine both (Kastner et al., 2020). It is no wonder that the casting of various polymer materials with different sorts of structural foaming is attracting even more attention with time. Compared to bulky polymer materials, polymer foam exhibits low density, good heat insulation, good sound insulation effects, high specific strength, and resistance to corrosion (Jin et al., 2019). Foamed plastics may be flexible, semi-rigid, or rigid, and their densities may range from 1.6 to over 960 kg/m3 (Rosato et al., 2004). In addition, they display easy recyclability, a better warpage behavior, higher stiffness-to-weight ratio, or higher energy consumption during biaxial bending tests (Kastner and Steinbichler, 2020).
Carbon Dioxide Conversions
Published in Saeed Sahebdelfar, Maryam Takht Ravanchi, Ashok Kumar Nadda, 1 Chemistry, 2022
Saeed Sahebdelfar, Maryam Takht Ravanchi, Ashok Kumar Nadda
High specific strength, light density, good thermal and sound insulation and strong energy absorption capability are advantages of polymeric foams. These foams have versatile applications in daily life, such as in thermal insulation, automotive and airplane parts, acoustic dampening, sporting equipment, microelectronic applications, packaging materials and optical devices. Waste disposal, flammability, blending agents influence on environment and recyclability are the issues that need to be investigated in polymer foam industry. Biodegradable foam materials improve the waste disposal and recyclability issues (Qin et al., 2015).
Static and fatigue compression behaviour of conventional and auxetic open-cell foam
Published in Mechanics of Advanced Materials and Structures, 2022
Karima Bouchahdane, Nouredine Ouelaa, Ahmed Belaadi
Indeed, structural foams are a subset of cellular materials [9, 10]. In recent years, the development of biodegradable foams through environmentally friendly foaming processes has been a key point in designing porous materials. Foams are used in many applications and can be rigid or flexible, have low or high densities, have closed or interconnected pores of different sizes and shapes, and have various distributions [11]. Polyurethane (PU) foams are one of the most important groups of plastics, so the increasing amount of waste makes recycling an urgent task [12–14]. There are different types of foams, such as Aluminum, Nickel, ceramic, polyethene, PVC, PVDF, PU, etc. Recently, these materials are receiving increasing attention as structural and functional materials [15, 16]. The latter occur widely in nature [17]. The mechanical behavior depends mainly on the type of base material, relative density, morphology and topology [18].
Biodegradability and ecotoxicity of polyurethane foams: A review
Published in Critical Reviews in Environmental Science and Technology, 2022
Kateřina Skleničková, Sabina Abbrent, Martin Halecký, Vladimír Kočí, Hynek Beneš
Despite the recent trend to limit the use of plastics worldwide, their production is steadily increasing (390 million tons in 2017) (PlasticsEurope, 2019). Polymer foams and cellular plastics form a significant part of the total plastic production due to their versatility, lightweight, excellent strength/weight ratio, superior insulating abilities, energy absorbing performance and comfort features (Klempner & Sendijarevic, 2004). They are highly demanded across industries such as automotive, building construction and packaging. The global polymer foam market reached USD 109.7 billion in 2018 and is expected to expand at the Compound Annual Growth Rate (CAGR) of 4.0% from 2019 to 2025 (GlobalNewswire, 2019; “Polyurethane, Polystyrene, Polyolefin, Melamine, Phenolic, PVC, 2019–2025,” 2019). The key types of polymer foams available on the market are polyolefin, polystyrene, polyvinylchloride (PVC), melamine, phenolic and polyurethane foams (Figure 1).
Techniques for harvesting, cell disruption and lipid extraction of microalgae for biofuel production
Published in Biofuels, 2021
Foam flotation works by removing the surface-active chemicals from water and dewatering dilute solid–liquid mixtures. Foam is generated by adding a surface-active chemical to the solid–liquid mixture and then injecting air bubbles to create a stable foam. Bubbles can be of various sizes, depending on the algae to be harvested, generally ranging from 10 to 3000 μm in diameter [8]. Foam is a complex network of interconnected liquid channels surrounding the bubbles. As liquid moves through this network, gravity promotes drainage, which is retarded by capillary action and friction at the channel walls. Hydrophobic particles adsorb to the air bubbles and are recovered from the top of the foam, and as a consequence of drainage within the foam will be dewatered to some extent. Bubble coalescence occurring within the foam may enhance dewatering by reducing channel area. To evaluate the harvesting potential of Chlorella sp., Coward et al. [52] used the foam flotation method. Latex beads were used for optimising the foam column and the highest concentration factors were obtained using cationic CTAB, a taller column, lower surfactant concentrations, and CTAB combined with high column heights. Concentration factors of up to 230 times can be produced using column height of 1.5 m and surfactant concentrations of 10 mg/L.