Homework 3

What is a polymer?

A compound consisting of long chain molecules, each molecule made up of repeating units connected together

What is a copolymer

A polymer composed of 2 different types of mers - i.e. ethylene and propylene

What is a plasticizer

Chemical added to polymer to make it softer and increase flexibility, often to make shaping more convenient

The copper-nickel system is a simple alloy system, as indicated by its phase diagram. Why is it so simple?

Copper nickel alloy is always a solid solution alloy regardless of the composition

Identify some of the properties for which aluminum is noted.

Cr, Mn, Mo, Ni, and V [INCORRECT; WILL FIX LATER]

What is cross-linking in a polymer and what is its significance?

Cross linking is the formation of onnetions between a polymer's long chain molecules, resulting in permanent alteration. If there is not that much cross-linking, polymer can transform into an elastomer. If cross-linking is signifcant, polymer becomes a thermoset

Given a copper nickel phase diagram (you should know what this looks like), how do you find the compositions of liquid and solid phases at a given temperature?

Draw a horizontal line at that given temperature - the intersection at L can be used to find the composition percentage of liquid phase, and same at the intersection for S

Elastomers and thermosetting polymers are both cross-linked. Why are their properties so different?

Elastomers are lightly cross-linked, so it allows extensibility. Thermosets are highly cross-linked so the polymer becomes more rigid

Define glass

Organic, nonmetallic material that cools to a rigid solid without crystallization

What is the feature that distinguishes glass from the traditional and new ceramics?

Other ceramics have a crystalline structure while glass uses a noncrystalline (amorphous) structure

T/F: branched molecular structure is stronger in the solid state and more viscous in the molten state than a linear structure for the same polymer

True

what is glazing, as applied to ceramics?

When oxides such as alumina or silica are applied as a surface coating to give the product a more impervious structure (reduce moisture)

Explain why aluminum, magnesium, and titanium are expensive when they are abundant on earth. Give a reason to recycle aluminum.

While they are abundant, it takes a lot of energy and electricity to prepare it so that it is in a form ready for manufacturing (extract from earth). Thus, recycling aluminum can save/reduce energhy

What typ eof atomic bonding characterizes the ceramics?

chemical bond - covalent and ionic bonding

What is the predominant alloying element in all of the stainless steels

chromium

which of the following alloying elements are most commonly associated with stainless steel (two best answers): chromium, manganese, molybdenum, nickel, and tungsten

chromium and nickel

Identify some of the important applications of zinc

die castings, coating in galvanized steel, alloying to make brass (with copper)

T/F: A ceramic material can be defined as an organic compound consisting of a metal or semimetal and one or more nonmetals

false

T/F: Glass ceramics are polycrystalline ceramic structure that have been transformed into a mostly glassy state

false

How do you use the inverse lever rule to determine the proportions of liquid and solid phases present in the alloy?

for proportion of liquid, its CS/(CS+CL). If solid, switch out CS in numerator with CL

An alloy is a metal composed of two or more elements, at least one of which is metallic. The two main categories of alloys are which two of the following: alloids, intermediate phases, metal compounds, phase solutions, and solid solutions

intermediate phases, solid solutoins

The iron tapped from the blast furnace is which of the following: cast iron, low alloy steel, low carbon steel, pig iron, pure iron, or stainless steel

pig iron

Which of the following plastics has the highest market share: phenolics, polyethylene, polyethylene, polypropylene, polystyrene, or polyvinylhloride

polyethylene

Glass products are based primarily on which mineral?

silica

Which figure shows the characteristic grain structure in a casting of a pure metal (u know what the pictures are - describe the one in ur head that is the right answer)

the pure metal does not have a segregation in the center, and is a clean upside down y

Of the 3 polymer types, which on is the most important commercially: elastomers, thermoplastics, or thermosets?

thermoplastics