Recycling of Plastics, Metals, and Their Composites

R.A. Ilyas, S.M. Sapuan, Emin Bayraktar

• Publisher: CRC Press
• Year: 2021
• ISBN:
  9781000521429
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Environmental Science
• Index: Biological Sciences

Having a solid understanding of materials recycling is of high importance, especially due to the growing use of composites in many industries and increasingly strict legislation and concerns about the disposal of composites in landfills or by incineration. Recycling of Plastics, Metals, and Their Composites provides a comprehensive review of the recycling of waste polymers and metal composites. It provides the latest advances and covers the fundamentals of recycled polymers and metal composites, such as preparation, morphology, and physical, mechanical, thermal, and flame-retardancy properties.

FEATURES

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• Offers a state-of-the-art review of the recycling of polymer composites and metal composites for sustainability

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• Describes a life-cycle analysis to help readers understand the true potential value and market for these recycled materials

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• Details potential applications of recycled polymer and metal composites

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• Includes the performance of natural fiber–reinforced recycled thermoplastic polymer composites under aging conditions and the recycling of multi-material plastics

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• Covers recycling technologies, opportunities, and challenges for polymer-matrix composites

This book targets technical professionals in the metal and polymer industries as well as researchers, scientists, and advanced students. It is also of interest to decision makers at material suppliers, recycled metal and polymer product manufacturers, and governmental agencies working with recycled metal and polymer composites.

1 Introduction to Recycling of Polymers and Metal Composites

R.A. Ilyas^1,2, S.M. Sapuan^3,4, Abdul Kadir Jailani⁴, Amir Hamzah Mohd Yusof⁴, Mohd Nurazzi Norizan⁵, Mohd Nor Faiz Norrrahim⁶, M.S.N. Atikah⁷, A. Atiqah⁸, and Emin Bayraktar⁹

¹School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, Johor, Malaysia

²Centre for Advanced Composite Materials (CACM), Universiti Teknologi Malaysia, Johor, Malaysia

³Laboratory of Biocomposite Technology, Institute of Tropical Forestry and Forest Products (INTROP), Universiti Putra Malaysia, Selangor, Malaysia

⁴Advanced Engineering Materials and Composites (AEMC), Department of Mechanical and Manufacturing Engineering, Faculty of Engineering, Universiti Putra Malaysia, Selangor, Malaysia

⁵Centre for Defence Foundation Studies, Universiti Pertahanan Nasional Malaysia (UPNM), Kuala Lumpur, Malaysia

⁶Research Center for Chemical Defence, Universiti Pertahanan Nasional Malaysia (UPNM), Malaysia

⁷Department of Chemical and Environmental Engineering, Universiti Putra Malaysia, Selangor, Malaysia

⁸Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, Selangor

⁹Mechanical and Manufacturing Engineering, SUPMECA, Saint-Ouen, France

DOI: 10.1201/9781003148760-1

CONTENTS

1. 1.1 Introduction
2. 1.2 Properties of Recycled Metal Composites
3. 1.2.1 Mechanical Properties
4. 1.2.2 Chemical Properties
5. 1.2.3 Physical Properties
6. 1.2.4 Thermal Properties
7. 1.3 Recycling Method of Polymer and Metal Composite
8. 1.3.1 Mechanical Recycling
9. 1.3.2 Chemical Recycling
10. 1.3.3 Thermal Recycling
11. 1.4 Impact of Recycling Polymer and Metal Composites on Environment, Industry and Economy
12. 1.5 Recycling of Polymer Composites
13. 1.6 Metal Recycling Composite
14. 1.7 Conclusions
15. Acknowledgment
16. References

1.1 Introduction

Composite products and structural components are one of the strongest manifestations of this interrelated mechanism in the creation of materials, structures and technology (Suriani, Radzi et al., 2021; Suriani, Rapi et al., 2021; Suriani, Sapuan et al., 2021; Suriani, Zainudin et al., 2021; Vasiliev & Morozov, 2018). As human technologies advance, the progress of material production follows the same route, and as this advancement is occurring humans should never forget their responsibility towards the environment and the fact that resources can be limited (Ilyas & Sapuan, 2019, 2020). Polymers' further application after use has been constantly coupled to their production; as the development of polymers improve, their recycling technology is lagging in comparison (Ignatyev et al., 2014). Recycling of this composite's material is important in the engineering field as it will promote the sustainability and continuous growth of industrial processes. The reason behind the stagnant progress in recycling technologies of composite (matrix and reinforcement) material is due to its heterogenous nature, making it a poor material to recycle (Yang et al., 2012). Another reason for the slow progress in composite recycling technologies is the added value after recycling is rather low; for example, a large amount of used plastic and synthetic textile is partly sent back to the economic cycle. Furthermore, compared to the recycling of metal, recycled polymer has some downgraded properties (Ignatyev et al., 2014). Thus, as the problem of recycling has become more common, it will not be impossible to discover a way to recycle polymer and metal composite with an efficient method.

Figure 1.1 shows the classification of composite material based on matrix (Figure 1.1a) and reinforcement material (Figure 1.1b). As recycling issues are becoming common, the industries and researchers are operating towards a circular economy where they focus on recycling, reusing, and remanufacturing products at the end-of-life (EOL) stage (Zhang et al., 2020). In addition, a tool that recognized the environmental burden of a composite material over its lifetime has been developed; it is called the life cycle assessment (LCA). LCA is beneficial to understand the ecological “pinch-points,” savings possibilities and method trade-offs (Tapper et al., 2020). Hence, it is not impossible for other methods and strategies to emerge and develope to counter the recycling issues, specifically recycling of polymer and metal composites, which are not easy to salvage.

Figure 1.1 Classification of composite material based on matrix and reinforcement material. Adapted with copyright permission from Yang et al. (2012).

However, increased composite structure production has meant that alternatives to simple disposal of components in waste sites have been required, with directives and other legislation aimed at reducing composite waste. A readily visible approach to recycle the composite materials is to replace the composite polymer structure and break the fibers in small lengths (e.g., carbon fiber) (Huntley et al., 2018). Many research and development (R&D) and technology that have been done to recycle the composite materials especially for fiber-reinforced composite materials. Due to broader applications in glass fiber-reinforced plastics and carbon fiber-reinforced composites, and longstanding requirements, a variety of distinct reprocessing technologies have been advanced and implemented for fiber-reinforced composite materials. These methods of recycling are classified as mechanical, chemical, and thermal. The composite material is minimized in sizes in most composite processing methods and comprises of fiber, polymer, and filler blends. The smallest elements are usually powdered, containing a higher amount of polymer and filler percentage while the grainier elements often have fibrous constitution, in which the products acquire a greater aspect ratio (Asmatulu et al., 2014). Figure 1.2 shows the recycling process of polymer composites and Figure 1.3 shows the methods of recycling for carbon fiber reinforced polymer (CFRP), respectively.

Figure 1.2 Recycling process of polymer composites.

Figure 1.3 Methods of recycling CFRP recycling (Zhang et al., 2020).

The objective of this chapter is to introduce the topic of recycling polymer and metal composite material, whether it is the recycling method, the problem related to recycling of polymer and metal composite material and progress in recycling polymer and metal composite material.

1.2 Properties of Recycled Metal Composites

A recent study by Ustundag and Varol (2019) compared the impact of recycled and commercially available PM titanium alloy properties; due to their high-strength properties and low aspect ratio, titanium alloys are used in many unique applicantions, such as pharmaceutical, military, athletic products and aerospace industries. This paper has reported from their experiments that the powder conduct during the milling process, the powder morphology of the recycled Ti–6Al–4V, is more rounded than the commercially available Ti–6Al–4V powder. Thus, commercially available alloys are more ductile and prevent intra-granular crack prolongation during a fracture, as spherical and rounded, formed powders have a lower impact fracture toughness, and material microstructures and phase distribution are influenced by temperature levels and durations during the sintering process (Ustundag & Varol, 2019).

1.2.1 Mechanical Properties

In recent research, Rady et al. (2020) have studied the physical and mechanical behavior of direct recycled aluminum alloy (AA6061) under heat treatment, where they have experimented on chipped aluminum in a high heat extrusion process, with varying temperature variables. The results have shown that the preheating temperature gives a more significant effect than the preheating time on the mechanical properties of the aluminum alloys (AA6061), where the increased temperature has given a higher tensile strength and lower microhardness. The heat treatment process was carried out with quenching temperatures reaching 530°C in 2 hours and aging processes at 175°C in 4 hours for optimal situations, where the tensile strength and microhardness of extruded samples have been greatly increased by heat treatment (Rady et al., 2020).

1.2.2 Chemical Properties

These approaches have been influential in the field because of the studies in the chemical properties of recycled metal composites. Recently, Liu et al. (2017)have experimented on mild chemical recycling and utilization of the decomposed resin of aerospace fiber/epoxy composite waste, where using a ZnCl₂/ethanol catalyst method, an effective approach to mild chemical recycling of carbon fiber reinforces polymers with a T_g of around 210°C was developed. As a result, the research has concluded that at moderate temperature degradation (less than 200°C) the recovered fibers were undamaged, while reactive multifunctional groups were formed in the decomposed matrix polymer, which was in the form of an oligomer. In addition, the high modulus and strength might also be maintained by the cross-linked polymers relative to the tidy polymer lacking the inclusion of decomposed matrix polymer, when the decomposed matrix polymer was utilized as a reactive element an...

Table of contents

• Cover
• Half Title
• Series Page
• Title Page
• Copyright Page
• Contents
• Preface
• Editors
• Contributors
• Chapter 1: Introduction to Recycling of Polymers and Metal Composites
• Chapter 2: Preparation of Metal Matrix Composites by Solid-State Recycling from Waste Metal/Alloy Chips
• Chapter 3: A Comprehensive Study on the Recycled Aluminum Matrix Composites Reinforced with NiAl Intermetallics and TiB2–TiC Ceramic Powders
• Chapter 4: Recycling for a Sustainable World with Metal Matrix Composites
• Chapter 5: Properties of Recycled Metal Matrix Composites
• Chapter 6: Morphology of Recycled Metal Composites
• Chapter 7: Performance of Natural Fiber Reinforced Recycled Thermoplastic Polymer Composites under Aging Conditions
• Chapter 8: Physical and Mechanical Properties of Recycled Metal Matrix Composites
• Chapter 9: Thermal Properties of Recycled Polymer Composites
• Chapter 10: Thermal Properties of Recycled Polymer Composites
• Chapter 11: Flame Retardancy of Recycled Polymer Composites
• Chapter 12: Mechanical and Tribological Properties of Scrap Rubber/Epoxy-Based Composites
• Chapter 13: Design for Recycling Polymer Composites
• Chapter 14: Effect of Heat Treatment Modification on the Tensile Strength and Microstructure of X7475 Al-Alloy Fabricated from Recycled Beverage Cans (RBCs) for Bumper Beam Applications
• Chapter 15: Recycling of Multi-Material Plastics in the Example of Sausage Casings Wastes
• Chapter 16: Influence of Recycled Steel Scrap in Nodular Casting Iron Properties
• Chapter 17: Optimization of Surface Integrity of Recycled Ti-Al Intermetallic-Based Composite on the Machining by Water Jet Cutting via Taguchi and Response Surface Methodology
• Chapter 18: Wear Behavior Analysis of a AlMg1SiCu Matrix Syntactic Foam Reinforced with Boron Carbide Particles and Recycled Fly Ash Balloons
• Chapter 19: Procedures for Additions of Wastes to Cementitious Composites – A Review
• Chapter 20: Analysis of the Scientific Production of Cementitious Composites with Recycled Polymeric Materials
• Chapter 21: Cementitious Composites for Civil Construction Made with Marble and Granite Waste
• Chapter 22: Influences of the Ceramic Inclusions on the Toughening Effects of Devulcanized Recycled Rubber-Based Composites
• Chapter 23: Evaluation of Mechanical and Microstructural Properties of Low-Density Concrete with Residual (Scrap) Vegetable Fiber and Blast Furnace Slag
• Chapter 24: Evaluation of Reinforced Concrete (RC) with Different Scrap Coarse Aggregates
• Chapter 25: Influence of Iron Content on the Microstructure and Properties of Recycled Al–Si–Cu–Mg Alloys
• Chapter 26: Polymer Recycling in Malaysia: The Supply Chain and Market Analysis
• Chapter 27: Life Cycle Assessment (LCA) of Recycled Polymer Composites
• Index