midterm Flashcards
What is NOT TRUE of plastics?
they are non-synthetic
Small molecules from which plastics are made are called _____.
monomers
The process by which the above molecules are combined is called _____.
polymerization
- true or false?
A crystalline polymer structure has crystal like (orderly) regions that when heated become amorphous.
true
- true or false?
Van der Waals forces are more electrical in nature and weaker than chemical (atomic) covalent bonds.
true
What molecular structure best describes a thermoset?
cross linked
Formation of side chains of the basic polymer backbone is ____________.
branching
- true or false?
Amorphous polymer structure materials have a sharp melting point.
false
In typical plastic product costs, about 75% of cost is attributed to…
material
What are the advantages of using plastic?
- relatively less energy to process
- good strength to weight ratio
- electrical insulation
- true or false?
Generally plastic grocery bags are heavier than paper for a given capacity
false
The EPA suggests four methods to deal with solid waste. Which is the least desirable?
landfill
______ is the most used method of disposing of municipal solid waste in America today.
landfilling
Which of the following has the highest BTU content (potential heat energy)?
High Density Polyethylene (HDPE)
- true or false?
Properly designed landfills act as a compost pit allowing biodegradable materials to return to their natural state.
false
- true or false?
According to the EPA, plastics account for the biggest portion of Municipal Solid Waste by weight in the landfill
false
- true or false?
Thermoset plastics can easily be heated and reformed into a new shape.
false
- true or false?
Epoxy adhesives are an example of a thermoset material.
true
Which plastics ARE considered to be in the polyfin family?
Polyethylene
Polypropylene
This high impact polymer is often used for appliance housings and helmets.
Acrylonitrile Butadiene Styrene (ABS)
This “slippery” material (low coefficient of friction) is often used for gears and fibers, but one drawback of this material is its high water absorption rate.
nylon
This is by far the most used plastic material.
polyethylene
This polyolefin material is often used in applications of “living” or integral hinges.
Polypropylene
Often “foamed” for insulation and packaging, this material is also transparent.
polystyrene
Siding, gutters, wire coating, and hoses are common uses of this material.
Polyvinyl Chloride (PVC)
A plastic surgeon may select this material to reshape your nose.
silicone
The billiard balls and the handle on your fry pan are likely to be made of this material.
phenolic
A unique thermoplastic, having extremely high heat resistance and a low coefficient of friction, originally used to coat frying pans is…
Polytetrafluoroethylene (PTFE)
- true or false?
Casting processes produce parts with little to no built in stress.
true
- true or false?
Casting is a good process to make varying shapes such as Sheets, Tubes, Rods, Tooling, Foams and other objects.
true
- true or false?
One difference between a casting process and a molding process could be the amount of force that is applied to the material.
true
Casting is considered a low cost method to produce low volume parts because…
- molds can be very inexpensive
- low volume production economy
- thermosets can be cast
In rotational molding, thermoplastic powder material joins together because it is…
self-fusing
Even distribution of the material to the mold surface in rotational casting is accomplished by using a…
biaxial rotation
- true or false?
Cast acrylic sheet can be produced by casting between panes of glass.
true
Which of the following casting processes would be used to produce a hollow coin bank with a detailed exterior surface?
slush casting
What is an advantage of rotational molding?
size range of parts
Which state has the highest rotomolding plants?
!! OHIO !!
Rotational Molding can use which of the following form of materials?
powder
liquids
pellets
The most used material in rotational molding is…
polyethylene
What mold material is often used for rotational molding?
aluminum
The Industrial breakdown of Rotational Molding shows that the largest percentage of products are…
toys
- true or false?
The PVC Welding we did in the lab creates a cohesive bond of the material
true apparently
- true or false?
The PVC welding process we performed in the lab utilized a filler rod of PVC
true
- true or false?
You should wear safety glasses while in the plastics lab
true
Wear what gloves when fiber glassing?
latex
The plastics is industry the _______ largest manufacturing industry in the United States, providing significantly to the nation’s economy.
third
The U.S. plastics industry employs more than ______ million workers.
1.1
The U.S. plastics industry creates $______ in annual shipments.
$279 billion
There are nearly ______ plastics facilities in the United States.
18,500
Since 1980, U.S. plastics industry shipments have grown _______ percent per year.
3.4%
Over the past _____ years, productivity in plastics manufacturing has grown _____ percent per year, which is faster than productivity growth for manufacturuing as a whole.
26
2.3%
No.1 state for plastics employment?
California
No.2 state for plastics employment?
Ohio
LOWEST typical plastics product costs?
space (1%)
What are the FOUR main characteristics or plastics?
- typically organic
- typically hydrocarbon
- synthetic (manmade)
- capable of being formed by heat and/or pressure
Who invented the first thermoplastic and when?
John Hyatt in 1868
What was the first thermoplastic?
Cellulose Nitrate (Celluloid)
Today, most paint & glues are _______.
plastics
What is stress?
amount of effort/force applied per unit area
What is strain?
deformation (change in length) to original length
What is tensile strength?
ability to withstand stress in tension
What is elasticity?
ability to return to original length
What is plastic?
pliable/deformed
What is the yield point?
stress at which deformation starts plastically
What is the modulus of elasticity?
(also called Young’s Modulus)
ratio of stress to strain