In addition to fundamental materials properties, selecting which material to use in an application can be limited by a number of factors. Some of these factors include the cost of production, availability of starting materials (natural resources), level of pollution resulting from the manufacturing process, and amount of waste produced at the end of the lifecycle of the application. In this lesson, I will present relatively brief overviews of economic, environmental, and societal considerations that are important in the materials selection process.
By the end of this lesson, you should be able to:
Lesson 2 will take us one week to complete. Please refer to the course calendar for specific due dates.
To Read |
Read pp 25-36 (Ch. 2) in Introduction to Materials ebook Reading on course website for Lesson 2 |
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To Watch | Making Stuff: Cleaner |
To Do | Lesson 2 Quiz |
If you have general questions about the course content or structure, please post them to the General Questions and Discussion forum in Canvas. If your question is of a more personal nature, feel free to send a message to all faculty and TA's through Canvas email. We will check daily to respond.
While you read the material for this lesson in your e-book and on the course website, use the following questions to guide your learning. Also, remember to keep the learning objectives listed on the previous page in mind as you learn from this text.
Read pp 25-36 (Ch. 2) in Introduction to Materials ebook
In this lesson, we're going to look at the economic, environmental, and societal issues of materials science. The textbook reading for this week will introduce these topics, while the additional text on this website will supplement the reading material and explore further the topics of green design and social justice with regard to materials. The video for this lesson, Making Stuff: Cleaner, explores the science and technology of making energy production and usage cleaner and more efficient. Materials development in generating, storing, and distributing energy towards creating a more sustainable future are highlighted in the video.
Read sections 20.1 - 20.4 in the customized e-book (answer quiz questions on those sections, and then return to this website).
First and foremost, a product must make economic sense. The price of a product must be attractive to customers, and it must return a sustainable profit to the company. To minimize product costs, materials engineers should consider three factors: component design, material selection, and manufacturing technique. Also, there could be other significant costs including labor and fringe benefits, insurance, profit, and costs associated with regulatory compliance. As the world has become more populated and that population is increasing its usage of the earth's natural resources, engineers are increasingly being asked to consider sustainable practices when developing new products. Also, since it is estimated that approximately half the energy consumed by the U.S. manufacturing industry is used to produce and manufacture materials, the efficient use of energy for manufacturing processes and utilization of sustainable energy sources when available is highly desirable.
Sustainability represents the ability to maintain an acceptable lifestyle at the current level and into the future while preserving the existing environment. Your textbook discusses one approach to achieving sustainability: green product design. In the next section, we will look at some green design principles and examples of their application. Before moving on to that section, please watch the following short video. This (1:53) video on using renewable feedstock to replace nonrenewable starting raw materials highlights a green design principle used to make processes more sustainable.
The term renewable feedstock refers to raw material that can be grown or produced by humans. The usage of renewable feedstock is attractive because it reduces the amount of harmful waste produced from the crude oil refinery and distillation processes. Most print inks are made from crude oil derived pigments. If you think about the amount of printing that is done on a global scale, this can be a problem in the long term.
Currently in development are soy-based inks which are derived from the oil of the soybean plum. As a plum, soybeans are a renewable resource. The production process of these inks is overall more environmentally friendly then their petroleum-based counterparts. Also, these soy-based inks are much brighter than the petroleum-based inks.
The recycling process of paper products printed with soy-based inks is also considerably more environmentally friendly. When paper products are recycled, the ink needs to be removed. Petroleum inks can be difficult to remove, but soy-based inks can be removed with relative ease.
There are three primary components of green design: reduce, reuse, and recycle. The reduce concept means to redesign a product to use less material. The reuse concept means to fabricate a product using material that can be used again. Recycling refers to the concept of reprocessing a product at the end of its lifecycle into new raw material that can be processed into new products.
One green design principle is that if there is less waste produced, then there is less to clean up. Please watch the following short (2:23) video that highlights this principle.
Another green design principle related to producing less waste is to produce waste that is biodegradable. Please watch the following short (2:06) video that highlights this green design principle.
Some processes result in waste that is toxic or hazardous. The following video (2:04) showcases a genetically modified bacteria that has been developed to produce an enzyme that, when used with glucose, can replace a known carcinogen in a widely used synthesis process. In addition, the replaced chemical is derived from nonrenewable fossil fuels, while glucose is readily available, non-toxic, and renewable.
For more efficient use of energy, synthesis processes should be designed to occur near room temperature and at atmospheric pressure to reduce the amount of energy used when possible. Heating, cooling, and increasing or decreasing pressure, requires energy. The following green chemistry principle video (1:26) discusses the advantages of designing your synthesis process to occur near room temperature and at atmospheric pressure.
Recycling of used products rather than disposing of them as waste is a desirable approach for several reasons. Recycled material replaces the need to extract raw materials from the earth. The energy requirements to process recycled materials are normally less, and in the case of aluminum much less, than the energy required to process extracted raw materials from the earth. In addition, recycling conserves natural resources and eliminates the ecological impact from the extraction of raw materials from the earth. Proper product design facilitates recycling, which reduces pollution emissions and landfill deposits.
Some issues surrounding recycling include that products must be disassembled or shredded to recover materials, and collection and transportation costs are significant factors in the economics surrounding recycling. The following video examines the anatomy of a properly designed landfill. After watching the video (4:39), proceed to your textbook and read section 20.5.
Read section 20.5 in the customized e-book.
In the next sections, we will be discussing the recycling of metals, glass, polymers, paper, and limits of recycling.
As mentioned in the e-book, aluminum is the most commonly recycled nonferrous metal. (Ferrous is Latin for iron, so a nonferrous metal is a metal which does not contain iron.) Aluminum is recycled because it takes a lot less energy to recycle aluminum than it takes to extract aluminum from bauxite ore, which requires heating and electrolysis. In addition, aluminum readily forms an oxide that forms a protective surface. This protective surface protects the bulk of the aluminum from oxidizing further. This results in most of the aluminum being recovered every time it goes to the recycling phase, in contrast to iron.
In the case of iron, oxidation, i.e., rust, does not protect iron from oxygen and water, and significant amounts of iron are not recyclable because the iron has been converted to rust. Please watch the following video (5:04) which summarizes the points about recycling of metals emphasized in your e-book and this website.
In the next section, we will discuss recycling of ceramics, in particular, the recycling of glass which is the most common commercial ceramic.
Glasses are the most common commercial ceramics, however, there is little economic incentive to recycle glass. The raw materials for producing glass are inexpensive and readily available. Glass is relatively dense, which makes it expensive to transport which adds to the costs of recycling. Glass must be sorted before being processed during recycling, usually done manually which adds to costs. Not all glass is recyclable, and the glass comes in many different forms. Please watch the following video (3:29) which summarizes the points about recycling of glass emphasized in your e-book and this website.
In the next section, we will discuss some of the limitations of recycling.
Recycling has a number of advantages. Properly done, it reduces the usage of raw materials, energy usage, air pollution, water pollution, and greenhouse gas emissions. There are, however, a number of limits to the effective implementation of recycling. Recycling can involve energy usage, hazards, labor costs, and practices by individuals and countries, which can hamper the efficient implementation of recycling plans. The biggest limit to recycling is that not all materials can be recycled and so materials can only be recycled a limited number of times due to degradation each time through the process. This degradation is referred to as downcycling.
In addition, recycling poses a number of societal and ethical issues. As highlighted in the e-book, e-waste recycling has led to electronic waste from developed countries being shipped to undeveloped countries for recycling. In many cases, this leads to low wages and terrible conditions for workers involved in the recycling process and the release of toxins which are environmental and health risks for the individuals and their surrounding communities. Please watch the following video (5:26) which summarizes the limits of recycling as discussed in your e-book and this website.
In the next section, we will discuss the recycling of polymers, in particular, plastics.
One way of classifying polymers is to break them up into two classes. The two classes of polymers are thermoplastic polymers and thermosetting polymers. The basic property that separates a thermoplastic polymer from a thermosetting polymer is the polymer’s response to being heated. When the thermoplastic polymer is heated, it melts, softens, and can be reformed when cooled. When the thermosetting polymer is heated, it hardens and cannot be reformed and stays hard when cooled. We will learn much more about each of these two classes of polymers and the reasons for their defining properties later in our lesson on polymer structures.
Since thermoplastic polymers can be melted and reformed, they are easily recycled. However, their properties do degrade with each reuse. Thermosetting polymers are much more difficult to recycle. Some of them can be ground up and used as filler for other processes, and, on a case-by-case basis, some can be processed to be broken down into their underlying base units which can be reused. Another approach to reducing the amount of plastic that ends up in our landfills is the development of biodegradable plastic. The idea here is that plastic can be made to breakdown (be compostable). In addition, bioplastics often come from renewable raw materials. But this leads to an ethical issue: do you use the available arable land for plastic or food production?
Now, please watch the following video (4:38) on plastics and biodegradable plastics which summarizes some of the issues around plastic recycling and bioplastics as discussed in your e-book and this website.
In the previous video, the incineration of waste was discussed. Incineration leads to a huge volume reduction of waste, which results in less waste ending up in the landfill. Waste in the landfill is the least environmentally friendly option. However, incineration typically results in less recycling, which would be a more efficient use of recyclable material than incinerating it. This reduction of recycling due to incineration is considered the major disadvantage of incineration. Although an important concern with incineration is the production of toxins, with proper technology these toxins can be managed. A segment of the video for this week, Making Stuff: Cleaner, discusses burning waste to create electricity. Please watch the following short video (4:40) which discusses burning waste to create electricity as well as the issues regarding incineration discussed above.
Lastly, please watch the following video (5:40) on the recycling of paper, which touches on several themes of this lesson including sustainability, downcycling, and green design principles.
Now that you have read the text and thought about the questions I posed, go to Lesson 2 in Canvas and watch the Making Stuff: Cleaner video (55 minutes). This video highlights some innovations in materials science that can potentially help make our technology use cleaner in the future. In "Making Stuff: Cleaner," in contrast to the readings of this lesson, the rapidly developing science and business of clean energy is explored. Some of the latest materials developments in generating, storing, and distributing energy are investigated in the hope of creating a sustainable future.
Go to Lesson 2 in Canvas and watch the Making Stuff: Cleaner Video (55 minutes). You will be quizzed on the content of this video.
Producing a sustainable society is one of the greatest challenges facing our society. The supply of natural resources, the creation of pollution during the manufacture of materials, recycling issues, and materials waste all issues of concern towards creating a sustainable society. By considering a material's total life cycle, utilizing materials life cycle analysis, and implementing a ‘green design’ philosophy, engineers can work towards alleviating some of these issues.
You have reached the end of Lesson 2! Double-check the to-do list on the Overview page to make sure you have completed all of the activities listed there before you begin Lesson 3.