Eylem Asmatulu

Recycling of fiber-reinforced composites and direct structural composite recycling concept

Fiber-reinforced polymer composites are engineered materials commonly used for many structural applications because of the high strength-to-weight and stiffness-to-weight ratios. Although the service life of these materials in various applications is usually between 15 and 20 years, these often keep the physical properties beyond this time. Recycling composites using chemical, mechanical, and thermal processing is reviewed in this article. In this review of carbon, aramide, and glass fiber composites, we provide, as of 2011, a complete view of each composite recycling technology, highlight the possible energy requirements, explain the product outputs of recycling, and discuss the quality (fiber strength) of recyclates and how each recyclate fiber could be used in the market for sustainable composite manufacturing. This article also includes the new concept of ‘direct structural composite recycling’ and the use of these products in the same or different applications as low-cost composite materials after small modifications.

Life cycle and nano-products: end-of-life assessment

Understanding environmental impacts of nanomaterials necessitates analyzing the life cycle profile. The initial emphasis of nanomaterial life cycle studies has been on the environmental and health effects of nanoproducts during the production and usage stages. Analyzing the end-of-life (eol) stage of nanomaterials is also critical because significant impacts or benefits for the environment may arise at that particular stage. In this article, the Woodrow Wilson Center’s Project on Emerging Nanotechnologies (PEN) Consumer Products Inventory (CPI) model was used, which contains a relatively large and complete nanoproduct list (1,014) as of 2010. The consumer products have wide range of applications, such as clothing, sports goods, personal care products, medicine, as well as contributing to faster cars and planes, more powerful computers and satellites, better micro and nanochips, and long-lasting batteries. In order to understand the eol cycle concept, we allocated 1,014 nanoproducts into the nine end-of-life categories (e.g., recyclability, ingestion, absorption by skin/public sewer, public sewer, burning/landfill, landfill, air release, air release/public sewer, and other) based on probable final destinations of the nanoproducts. This article highlights the results of this preliminary assessment of end-of-life stage of nanoproducts. The largest potential eol fate was found to be recyclability, however little literature appears to have evolved around nanoproduct recycling. At lower frequency is dermal and ingestion human uptake and then landfill. Release to water and air are much lower potential eol fates for current nanoproducts. In addition, an analysis of nano-product categories with the largest number of products listed indicated that clothes, followed by dermal-related products and then sports equipment were the most represented in the PEN CPI (http://www.nanotechproject.org/inventories/consumer/browse/categories/2010).

Recycling of Aircraft: State of the Art in 2011

Recently, the end-of-service life for aging aircraft and related parts has become a key subject in recycling industries worldwide. Over the next 20 years, approximately 12,000 aircraft currently utilized for different purposes will be at the end of service. Thus, reclaiming retired aircraft by environmentally responsible methods while retaining some of the value becomes a significant need. Recycling aircraft components and using these in different applications will reduce the consumption of natural resources as well as landfill allocations. Compared to the production of virgin materials, recycling aircraft will also reduce air, water, and soil contaminations, as well as energy demand. In the present study, we have investigated the environmental benefits of recycling and reusing aircraft components in the same or similar applications as low-energy input materials. During the aircraft recycling, most of the aircraft components can be recycled and reused after reasonable modifications and investments.

Recent progress in nanoethics and its possible effects on engineering education

Nanotechnology can improve many physical, chemical, physicochemical, and biological properties of materials, which can be very useful for many industries, including the biomedical, aerospace, textile, cosmetics, manufacturing, oil, agricultural, defense, and electronics industries. However, nanotechnology products (or nanomaterials) can be hazardous because of the way they are manipulated on an atomic scale. Since nanomaterials, such as nanotubes, nanoparticles, nanowires, nanofibers, nanocomposites, and nanofilms, are all new, produced with entirely new manufacturing techniques, there are no specific rules and regulations for them. In the present nanoethics study, we provide a detailed report of the ethical, social, philosophical, environmental, safety, and legal issues surrounding nanotechnology and its products, which can be very useful for the training and protection of students, as well as scientists, engineers, policymakers, and regulators working in the field.

Chapter 5 – Nanotechnology safety in the automotive industry

A number of nanoscale materials have been developed and utilized for the physical, chemical, and physicochemical property improvement of parts and devices used in the automotive industry. The quantity of these nanomaterials has been growing rapidly because of their extraordinary properties. Nevertheless, recent studies conducted on their toxicity have shown that some of them, in differing surface areas, sizes, shapes, surface charges, and compounds, interact with human cells or organs and damage them, block blood flow, and cause other serious illnesses. If we understand the causes and mechanisms of these nanomaterial interactions in the automotive industry, it’s more than likely we will find cures for the deadly diseases associated with them. In this chapter, we report, in detail, on those nanomaterials, health and safety issues, and protection methods and present recent developments in the field that may be useful for workers’ protection.

Thermoset composite recycling - Driving forces, development, and evolution of new opportunities

Thermoset composites represent a substantial challenge for recycling, even as composite products increase in market interest. The concept of putting all future thermoset composite products into landfills over the next decades is unlikely to continue. This paper examines the three eras in the history of thermoset product recycling, the drivers for increased recycling, and possible future trends. Technology for managing thermoset composite products at end-of-life first focused on retrieving fiber and to a lesser extent resin. Then in a second era, research focused on better utilization of recovered fiber and finally the third era is now keeping more of the original resin–fiber structure to reuse these composites. Drivers are emerging to stimulate thermoset recycling, including States with success in recycling other challenging products (tires, carpets, automobile parts, etc.) setting policy and fees to encourage recycling. The evolution of heat recovery as a thermoset recycling option in Europe is another driver. Additionally, efforts at certification of recycled fiber quality may stimulate greater reuse.

Chapter 3 – Safety and ethics of nanotechnology

Abstract Nanotechnology is one of the ways of improving many properties of materials, including physical, chemical, physicochemical, and biological, which can be useful for various applications in biomedical, textile, aerospace, manufacturing, cosmetics, oil, defense, agricultural, and electronics industries. Nevertheless, nanotechnology products, or nanomaterials (e.g., nanotubes, nanoparticles, nanofibers, nanowires, nanocomposites, and nanofilms), can be unsafe to human health because of the way they are manipulated and treated at near atomic scale. Since these nanomaterials are produced with mainly new manufacturing techniques and have various sizes, shapes, and surface energies, they may also create some uncertainties because of the lack of specific rules and regulations governing their manufacture and manipulation. This study provides a detailed report on the safety and ethics of nanotechnology and related ethical, social, philosophical, environmental, biological, and other legal issues. The information provided here can be very useful for training and protecting scientists, engineers, students, policymakers, and regulators working in the nanotechnology and related technologies.

Integrating Spirulina platensis cultivation and aerobic composting exhaust for carbon mitigation and biomass production

Aerobic composting is an effective way to dispose of organic waste. However, considerable carbon is converted into CO2 and emitted into the atmosphere, which is a waste of the carbon resource and has the potential for the greenhouse gas effect. In this study, an innovative approach coupling aerobic composting exhaust and Spirulina platensis cultivation has been proposed and investigated, resulting in a double-edged solution to mitigating waste and co-generating biomass with a minimal cost of CO2 supplied in the culture. Experimental results showed that the maximum biomass productivity ranged from 56.61 to 58.38 mg·L-1·day-1 was achieved using aerobic composting exhaust as a carbon source. Moreover, the CO2 fixation rates of 46.36 mg·L-1·day-1 and 76.81 mg·L-1·day-1 were obtained by S. platensis cultivation. Finally, the chemical composition analysis of S. platensis biomass obtained in an optimum condition showed an abundance of proteins and lipids, thereby indicating its great potential for biofuel industry.

Investigating compression strengths of 3D printed polymeric infill specimens of various geometries

Conventional manufacturing techniques include removing the excess materials to get the desired shapes; however, additive manufacturing include direct manufacturing of the objects using computer aided design model through adding a layer of material at a time. Strength and durability of the final products are important issues in designing 3D printed functional objects. Primary considerations of 3D printing process include some specifications of the printing process, printing orientation, materials selection and overall design (complexity, size, pore volume and shape). Infill structures are printed in selected patterns with a desired solid percentage, which is arranged using the slicing software. Percent rate and designed pattern are two key parameters for infill specimens which affect the print time, material usage, weight, strength, and decorative assets, as well. Polylactic acid (PLA) is a biodegradable and bioactive thermoplastic derived from renewable resources, such as corn starch, sugarcane, cassava and so on. In this study, five different infill shapes (e.g., solid, diamond, hexagonal, square, and triangle) of PLA were designed using CATIA program, and then 3D printed with 20, 40, 60, 80 and 100 vol.% to determine the effects of the infill shapes on the compressive strengths of the materials. The purpose of this study is to investigate the infill shapes, volumes, and orientation of infill shapes in the 3D printed specimens. Compression test results showed that infill shapes and volume percentages affect the mechanical properties of the 3D printed parts. This study indicated that mechanical properties of 3D printed materials could be maximized using the different infill shapes and volume percentages in 3D printing process.

Sustainability of fiber reinforced laminate and honeycomb composites in manufacturing industries

Fiber reinforced polymer (FRP) composites provide a lot of benefits, including strength-to-weight ratio / light weight, superior mechanical properties, low maintenance, prolonged service life, as well as corrosion, fatigue and creep resistance. However, sustainability of the FRP composites have not been studied in detail in terms of long term productions in various industries, such as aerospace, wind energy, automotive and defense. Carbon fibers are relatively expensive because of the energy intensive production systems, and lack of easy production options, which forces many companies to recycle and reuse the FRP composites in the same or different manufacturing industries. This study mainly deals with two important issues, including the disposal of composite wastes generated during the manufacturing of composite parts, and the disposal of the products at the end of their useful life. It is believed that the carbon fibers in the used composites will have still high mechanical strengths to use in different composite manufacturing after its end of life. The major manufacturing costs come from the labor and raw materials, so using the recycled carbon fibers will make sustainable composite productions in other industries. This paper presents the current status and outlook of the FRP composite recycling and re-manufacturing techniques in the same or different industries. A future vision of the FRP composites will be investigated with sustainability point of views. This study will also mention about the sustainability issues in laminate and honeycomb composites, new product design and developments and potential applications in different manufacturing industries.