Introduction to Plastics Engineering

Anshuman Shrivastava

• Publisher: William Andrew
• Year: 2018
• Print ISBN: 9780323395007
• eBook ISBN: 9780323396196
• Topic: Technology & Engineering
• Subtopic: Engineering General
• Index: Technology & Engineering

Introduction to Plastics Engineering provides a single reference covering the basics of polymer and plastics materials, and their properties, design, processing and applications in a practical way. The book discusses materials engineering through properties formulation, combining part design and processing to produce final products. This book will be a beneficial guide to materials engineers developing new formulations, processing engineers producing those formulations, and design and product engineers seeking to understand the materials and methods for developing new applications. The book incorporates material properties, engineering, processing, design, applications and sustainable and bio based solutions.Ideal for those just entering the industry, or transitioning between sectors, this is a quick, relevant and informative reference guide to plastics engineering and processing for engineers and plastics practitioners.- Provides a single unified reference covering plastics materials, properties, design, processing and applications- Offers end-to-end coverage of the industry, from formulation to part design, processing, and the final product- Serves as an ideal introductory book for new plastics engineers and students of plastics engineering- Provides a convenient reference for more experienced practitioners

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Introduction to Plastics Engineering

Abstract

This chapter introduces the readers to plastics engineering and discusses the concept of macromolecules and polymers that are used to make various plastic parts. Polymers are obtained from variety of sources that are discussed here. Differences in morphology, temperature dependency, and properties of various plastics materials make them suitable for end application. The author briefly discusses the regulations that govern safe making and use of plastics materials.

Keywords

Plastics engineering; polymers; macromolecules; commodity plastics; source of polymers; morphology; temperature dependency; commodity and engineering plastics; regulations

1.1 Introduction to Plastics

Plastic products have become significant part of our daily life. The clothes we wear, the toothbrush we clean our teeth with, the storage containers we carry and heat our food in, the cars we drive, the electronic devices we use to communicate, the credit cards to make payments, and several such products have become essential to everyday living. These products are typically made from different types of plastic materials.

The word plastic or plastics is derived from Ancient Greek word plastikos meaning “fit for molding” and from Latin word plasticus meaning “of molding” [1]. Both words indicate forming shapes or molding by heating. Thus, shaping of plastics using heat and pressure creates the foundation of almost all plastic manufacturing processes. Typical to these manufacturing and technological processes, the plastic materials are usually made soft by applying heat [2]. The softened plastic is then given a desired shape to fit the application. Once it attains the shape, the material is then cooled to let it harden and retain the shape.

Plastic products are widely accepted primarily due to their lower cost and lighter weight. Ease of processability, resilience, recyclability, and versatility add to the benefits of adapting to plastics. During the last century, the development and acceptance to plastics have raised the comfort and standard of living. In absence of plastic products, today’s clean water, food distribution, healthcare, apparel, automobiles, aircraft, agriculture, and consumer goods would be unimaginable.

Plastics entered large-scale applications after the Second World War and quickly began to revolutionize daily life by replacing expensive and scarcely available metallic counter parts. Millions of plastic products offering unique functions and conveniences are routinely used. The end uses of plastic vary from simple economical commodity merchandize to expensive complex products for application in aerospace, automobiles, medical drug delivery devices, prosthetics, grafts, and others. To understand the growing diversity and complexity of plastic products, it becomes imperative to explore “plastics engineering” as a scientific field.

1.2 Plastics Engineering

Plastics engineering as a field focuses on designing, developing, and manufacturing of plastic parts that satisfy the requirements of the intended application. This means that each plastic product that is designed for specific application has to satisfy the three “F’s” as form, fit, and function for that application.

As we review examples of wearable safety, it would be clearer how form, fit, and function alter with application. In discussing “wearable safety for eye protection,” the form would be to produce rigid structure in the form of wearable safety glasses, fit would be to develop the shape and size that comfortably fit the user typically around the eyes and ears, and the function would be the ability of selected material to safeguard against foreign objects as a protective barrier, without interfering with user’s normal vision.

Similarly, reviewing “wearable safety for body armor,” the form would be to produce a flexible vest that could be worn around the chest and shoulders, the fit would be to develop sizes that are able to fit different body types, and function would be the ability of the selected material to protect against bullets and other such fast-moving objects at close range, yet remain lightweight for the user’s comfort.

The examples of “wearable safety” demonstrates how engineering a plastic product incorporates the knowledge of various interdisciplinary fields in designing of form, fit, and function for a product. Fig. 1.1 illustrates plastics engineering as an interdisciplinary field that relies on various scientific and technical disciplines. Plastics engineering not only combines the concepts of form, fit, and function, which involves design principles, but also encompasses the knowledge of various scientific and engineering fields that requires a good understanding of materials, their properties, processing methods, design principles, functional requirements, and the application.

Figure 1.1 Plastics engineering as an interdisciplinary field [3].

Understanding the engineering of plastics is necessary for developing innovative, safe, economical, and convenient solutions to meet the expanding demands universally. To learn about plastics engineering, one needs to develop a basic understanding of its fundamental principles, design techniques, processing methods, material properties, and governing regulations. One of the first steps to grasp the fundamentals of polymer engineering is to understand the macromolecules and polymers that make the backbone of all plastic materials.

1.3 Concept of Macromolecules and Polymers

Atoms form the building blocks of every particle in this universe. Two or more atoms combine to form a molecule. For example, two atoms of hydrogen and one atom of oxygen combine to form a molecule of water. When large number of such molecules are combined together, giant molecules are formed and these also known as macromolecules or polymers. The word polymer, which is derived from Greek terms poly meaning many and mer meaning parts, is defined as a chemical compound made up of small molecules (monomers) that are arranged in simple repeating structure to form a large molecule or a chain [4–6].

Hundreds and thousands of monomers are chemically bonded together by covalent bonds to form a polymer. Fig. 1.2 illustrates bonding of monomers to form a polymer. In this figure, the monomers are represented by circles and a straight line is used to represent a bond. The bonding process combines the monomers to produce a polymer [6,7]. Most polymers are organic materials consisting of carbon, hydrogen, oxygen, nitrogen, and sulfur. Other elements appear in polymer structures far less frequently than the listed five constituents.

Figure 1.2 Bonding of monomers to form a polymer [7].

1.4 Sources of Polymers

All plastics are made of polymeric materials. These polymeric materials can occur in the plants and animals or could be artificially produced in laboratories. Plastic materials are broadly categorized as natural, semisynthetic, or synthetic based on their source of origin.

1.4.1 Natural

Natural polymers are defined as materials that widely occur in nature or are extracted from plants or animals. Natural polymers are essential to daily life as our human forms are based on them. Some of the examples of natural polymers are proteins and nucleic acid that occur in human body, cellulose, natural rubber, silk, and wool. Starch is a natural polymer that is made up of hundreds of glucose molecules, similarly natural rubber is a polymer obtained from the latex of a rubber tree. Honey is another example of naturally occurring polymers that are significantly used in everyday life. Fig. 1.3 illustrates natural polymers from plant (latex from rubber trees) and animals (honey from bees).

Figure 1.3 (A) Latex from the rubber tree [8] Taken from https://commons.wikimedia.org/wiki/File:Sri_Lanka-Rubber_plantation_(5).webp and (B) Honey an natural polymer from bees [9]. Taken from https://pixabay.com/en/honey-honeycomb-sweet-2201210

1.4.2 Synthetic

Synthetic polymers are defined as polymers that are artificially produced in laboratories. These are also known as man-made polymers. Some of the examples of synthetic polymers are polyethylene (PE), polystyrene (PS), polyamides (nylon), poly(vinyl chloride) (PVC), synthetic rubber, teflon, epoxy, and several others [10].

Synthetic polymers are typically derived from petroleum oil in controlled environment and are made up of carbon–carbon bonds as their backbone. A combination of heat and pressure in the presence of a catalyst alters the chemical bonds that hold monomers together,...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Dedication
• Preface
• 1. Introduction to Plastics Engineering
• 2. Polymerization
• 3. Plastic Properties and Testing
• 4. Additives for Plastics
• 5. Plastics Processing
• 6. Plastics Part Design and Application
• 7. Environmental Aspects of Plastics
• Index