ABSTRACT
Fibre-reinforced plastic (FRP) materials are attracting growing interest because of their high specific mechanical properties. These characteristics, in addition to a high level of tailorability and design of freedom, make them attractive for marine, aerospace, automotive, sports and energy applications. However, the large use of this class of material dramatically increases the amount of waste that derives from end-of-life products and offcuts generated during the manufacturing processes. In this context, especially when thermosetting matrices are considered, the need to deeply study the recycling process of FRPs is an open topic both in academic and industrial research. This review aims to present the current state of the art of the most affirmed recycling technologies used for polymeric composites commonly used in industrial applications, such as carbon and glass FRPs. Each recycling method (i.e., chemical, thermal and mechanical) was analysed in terms of technological solutions and process parameters required for matrix dissolution and fibre recovery, showing their advantages, drawbacks, applications and properties of the recycled composites. Therefore, the aim of this review is to offer an extensive overview of the recycling process of polymeric composite materials, which is useful to academic and industrial researchers that work on this topic.
ABSTRACT
Carbon fibre and carbon fibre reinforced polymer matrix composites (CFRPs) are important lightweight materials for aerospace, automotive, rail transport, infrastructure, and renewable energy applications. This paper provides a comprehensive review on the history of carbon fibres and carbon fibre composites, the current global CFRPs consumption, and trends for future developments in the aerospace, wind turbine, automotive, pressure vessels, sports and leisure, and construction sectors. The history of carbon fibres and CFRPs is discussed over four representative periods including their early development (1950–60's), growth of carbon fibre composites industry (1970–80's), major adoption of carbon fibre composites (the first wave, 1990–2000's), and expanded use of carbon fibre composites (the second wave, 2010's and beyond). Despite a 37% decline of carbon fibre consumption in the aerospace industry in 2021 caused by COVID-19, the global CFRP demand was around 181 kt which more than doubled its value in 2014. There is tangible projected increase over the next five years and the demand for CFRPs is expected to reach 285 kt in 2025, mainly attributed from the fast expansion of non-aerospace industries such as the wind energy sector. Lower cost carbon fibres (e.g., large tow) and associated manufacturing technologies are continually evolving. Finally, the implications of emerging materials and manufacturing methods in conjunction with recycling and reuse for carbon fibre composites are discussed. [ FROM AUTHOR]
ABSTRACT
Advancements in polymer science and engineering have helped the scientific community to shift its attention towards the use of environmentally benign materials for reducing the environmental impact of conventional synthetic plastics. Biopolymers are environmentally benign, chemically versatile, sustainable, biocompatible, biodegradable, inherently functional, and ecofriendly materials that exhibit tremendous potential for a wide range of applications including food, electronics, agriculture, textile, biomedical, and cosmetics. This review also inspires the researchers toward more consumption of biopolymer-based composite materials as an alternative to synthetic composite materials. Herein, an overview of the latest knowledge of different natural- and synthetic-based biodegradable polymers and their fiber-reinforced composites is presented. The review discusses different degradation mechanisms of biopolymer-based composites as well as their sustainability aspects. This review also elucidates current challenges, future opportunities, and emerging applications of biopolymeric sustainable composites in numerous engineering fields. Finally, this review proposes biopolymeric sustainable materials as a propitious solution to the contemporary environmental crisis. © 2022 Elsevier Ltd.
ABSTRACT
With respect to the explosion of single-use plastic packaging consumption during the COVID-19 pandemic, environmentally friendly substitutes are critically needful for sustainable development. Therefore, the present work focuses on the functional properties of bioplastic blends prepared through hot compressing molding of thermoplastic starch (TPS) and spent coffee grounds (SCG) in different ratios (0%–20% SCG) as the potential features of SCG were extensively employed in biocomposites for the first time. The insertion of dark brown SCG into TPS hindered UV transmission by 100% at 320 nm and 99.2% at 400 nm. Moreover, the samples with 15% and 20% SCG induced a surge in radical scavenging activity from 7.95% to over 92% at a concentration of 0.1 g/ml owing to the rich source of antioxidants in SCG. The lignin component and high carbon content also improved the thermal performance of TPS/SCG blends, enhancing thermal stability, delaying onset and maximum degradation temperatures, and achieving the HB rating in the UL-94 test. Compared to a pure TPS matrix, TPS blends incorporating up to 10% SCG exhibited improvement in elastic modulus without deterioration of tensile strength. © 2022 Society of Plastics Engineers.
ABSTRACT
Carbon-fiber-reinforced polymers (CFRPs) are increasingly used in a variety of applications demanding a unique combination of mechanical properties and lightweight characteristics such as automotive and aerospace, wind turbines, and sport and leisure equipment. This growing use, however, has not yet been accompanied by the setting of an adequate recycling industry, with landfilling still being the main management route for related waste and end-of-life products. Considering the fossil-based nature of carbon fibers, the development of recovery and recycling technologies is hence prioritized to address the environmental sustainability challenges in a bid to approach mitigating the climate emergency and achieving circularity in materials’ life cycles. To this aim, we scaled up and tested a novel semi-industrial pilot plant to pyrolysis and subsequent oxidation of uncured prepreg offcuts and cured waste of CFRPs manufacturing. The environmental performance of the process proposed has been evaluated by means of a life cycle assessment to estimate the associated carbon footprint and cumulative energy demand according to three scenarios. The scale-up of the process has been performed by investigating the influence of the main parameters to improve the quality of the recovered fibers and the setting of preferable operating conditions. The pyro-gasification process attested to a reduction of 40 kgCO2eq per kg of recycled CFs, compared to virgin CFs. If the pyro-gasification process was implemented in the current manufacturing of CFRPs, the estimated reduction of the carbon footprint, depending on the composite breakdown, would result in 12% and 15%. This reduction may theoretically increase up to 59–73% when cutting and trimming waste-optimized remanufacturing is combined with circular economy strategies based on the ideal recycling of CFRPs at end-of-life.
ABSTRACT
Fogging on transparent surfaces such as goggles causes a series of hazards to users. To fabricate antifogging and low-haze transparent renewable polymer materials, intrinsic hydrophilicity with high water adsorption capability of thermoplastic starch (TPS) had been adopted. Strikingly, when benzoic acid (BA) was blended with thermoplastic starch (TPS-BA), the haze of TPS-BA was only 7.8% when it suffered the cold and warm method of antifogging measurement with 87% transmittance. Simultaneously, TPS-BA achieved an 18 mm inhibition zone for Staphylococcus aureus. To reveal the antifogging mechanism of TPS-BA films, the surficial and interior structure features were evaluated by three-dimensional optical scanner, scanning electron microscopy (SEM), contact angle testing, small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), temperature-dependent Fourier transform infrared (FTIR), dynamic mechanical analysis (DMA), and so on. The incorporation of BA resulted in the roughness (Rq), water contact angle (WCA), and crystallinity of the TPS-BA film decreasing from 6.5 to 0.68 μm, 65.1 to 39.9°, and 13.6 to 6.3%, respectively. The amorphous matrix and smooth surface reduced the scattered light, allowing the TPS-BA film to achieve low haze performance and high transmittance. Importantly, the diversified and weakened hydrogen bonds formed among starch, BA, and glycerol could inhibit the formation of starch crystalline regions and allowed hydroxyl groups to quickly bond with water. Thus, when TPS-BA is placed in a high-humidity surrounding, an "expressway"is constructed for water molecules diffusing into the TPS-BA matrix. This novel low-haze, antifogging, sustainable, and facilely fabricated TPS with antibacterial properties is a promising candidate in disposable medical goggles to fight against COVID-19. © 2021 American Chemical Society. All rights reserved.