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Chem in Context II Chapter 9
Terms in this set (82)
Plastics and Polymer
natural and synthetic
non-renewable materials (now sometimes renewable materials)
Non - renewable source
converted to fuels
starting point for plastics and pharmaceuticals
"big six" all made from crude oil
Renewable Source Examples
Cargill Dow: "Nature Work PLA" from corn glucose
DuPont: "Sonora" - family of polymers from corn based substances
what is a polymer?
chain of COVALENTLY bonded atoms
thousands of atoms long
"repeat unit" of the polymer
What is a Plastic?
"capable of being molded" (noun and adjective)
SYNTHETIC polymers - other materials may have plastic properties
are all polymers plastics?
some polymers occur naturally
Starch, wool, cotton, silk, natural rubber, skin, hair
Why do we make synthetic polymers?
aim to find substitutes for natural polymers
replace heavier materials like steel
Start with the simplest monomer: ethylene
C=C bond is broken
each C can bond to other atoms (use a free radical initiator)
linear or branched
Free Radical Initiator
very reactive species with an unpaired electron
Chain branching affects
because of intermolecular forces (forces between molecules)
attractive forces b/t molecules resulting from distortion of the electron clouds
effect is greater on bigger molecules and more closely packed molecules
Effects of Chain Branching on Dispersion Forces
affects flexibility of polymer:
more flexible = more branched (looser packed)
more rigid = less branched (tighter packed)
Which is more branched, LDPE or HDPE
LDPE is more branched - grocery bags, bubble rap
HDPE - milk jugs
example of Polyethylene (__PE)
the "Big Six"
over 60,000 synthetic polymers exist
75% made of SIX types
ALL are COLORLESS
what are the big six?
PET Polyethylene Teraphthalate
Low density Polyethylene
Soft, flexible, unreactive
plastic bags, insulation, bubble wrap, "dispenser" type bottles
high density polyethylene
stiffer than LDPe
stiff plastic bags, milk jugs
rigid, strong, resists solvents and oils
pipes, siding, credit cards
PLASTICIZER added to make it flexible for hose, shower curtains
very clear, rigid, dissolves in many solvents
styrofoam insulation and drinking glasses
rigid, strong, shiny, impermeable
battery cases, carpets, bottle caps
transparent, strong, impervious to gases
soda bottles, clothing (recycled!)
Thermoplastic vs Thermosetting
Thermoplastic: can be melted and shaped repeatedly, tend to be flexible (all of the "big six")
Thermosetting: cannot be re-melted and shaped. often brittle. Melamine used in dishes, trays, and utensils - bakelite is another example
Crystalline, Amorphous, Plasticizers
Dominant in HDPE, PP
orderly arrangement of molecules
molecules tend to be close
regions make polymers rigid and strong
Dominant in PET, PS, PVC
molecules = further apart
regions make polymers flexible
disrupt crystallinity making polymer more flexible
these have come controversial
making Polyvinyl Chloride
can combine the monomer 3 ways
head to head, tail to tail
head to tail, head to tail (pipes, toys, siding: strong, impervious to oils &solvents)
random (hoses, shower curtains)
affects flexibility of polymer
head to tail head to tail
strong tough, resistant chemicals, carpeting, car battery boxes
Blowing Gases (making) Plastic foam
Random usually used
brittle and clear
Not foamed: CD cases, exterior on TV's and radios
Sytrofoam: mix polystyrene and volatile liquid
Environmentally friendly Peanuts
Dow Chemical: use CO2 as foaming (blowing) agent
the CO2 comes from existing processes - no extra was made
uses some CO2 that would be in the atmosphere and removes a use for CFC's
1996 Presidential Green Chemistry Award
Different method: TWO monomers join, a tiny molecule is split out (condensed)
Organic reaction (memorize***)
Alcohol + Carboxylic Acid --> Ester + Water
What does using Bifunctional monomers create in this reaction?
what is a Polyester?
many esters, linked together
Example of a polyester
If only one ester link has been made
NOT a polymer
just called an Ester
Organic reaction #2 (memorize***)
Amine + Carboxylic Acid --> Amide + Water
What does using Bifunctional monomers create in this reaction?
Polyamide (many amides linked together)
Example of a polyamide
monomers in Nylon condensation polymerization
adipic acid, hexamethylenediamine
Amide linkage =
Who created Nylon?
Wallace Carothers at Dupont
Uses of Nylon
Parachutes, stockings, (rationed during WWII)
Amino Acids are molecules which contain
Amine and Carboxylic Acid
Amino acids can create
Polyamides based on amino acids are also known as
Proteins make up
Skin, hair, muscles, enzymes
How many amino acids occur naturally?
R in amino acids =
any functional group
where do we dispose of most plastics
alternative forms of disposal
incineration, biodegradation, reuse, recycle, reduction
Incineration of plastics (in a municipal facility NOT a burn barrel)
per pound has more energy than coal
generates CO2, HCL, Phosgene (COCL2) and leaves ash with heavy metals (small amount of ash that can be extracted)
Biodegradation - is it common?
takes certain conditions
Big Six not broken down by bacteria
Do naturally occurring polymers break down in landfills?
Why do naturally occurring polymers not break down in landfills?
anaerobic (oxygen-free) conditions in landfills
Percents of paper and plastic in landfills
Plastic = 11%
Paper = 35%
Can all of the Big Six be recycled?
Yes in THEORY
Is the US recycling more than ever before?
What has happened to the percent of plastics being recycled in the US?
more is being manufactured
Why has recycling plastic decreased?
Consistent availability requires reliable collection facilities.
Consistent purity requires thoroughly sorting AND cleaning
price of crude oil (virgin plastic is cheap)
ends up in flowerpots or plastic lumber
PET bottles can become what?
Polyester fabrics: fleece, carpeting, tops of running shoes
LPDE grocery bags can become what?
more bags! return to grocery store
Recycled - Content
has recycled materials IN it
two kinds of 'Content'
from scraps, trimmings, manufacturing process (cleaner and easer for manufacturer )
from the trash - industrial or consumer (this one is the best!!!)
Recyclable only applies to certain products
"% post consumer waste"
How can you reuse / reduce?
take styrofoam peanuts to smaller shipping stores
look for plasticware that is made with "less plastic"
avoid excessively packaged products
Alternative Plastics recycling
DuPont has developed a process to break PET back into monomers
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