Polymers
1 Polymers
- Source and Uses of Plastics
- Polymer Synthesis
- Polymer Structure & Properties
- Paper or Plastic?
2 U.S. Plastic Production
3 Plastic Uses
4 Source of Plastics
The raw materials (monomers) for plastics come from crude oil (petroleum). Shown below are the typical uses for a barrel of crude oil.
| Use | Gallons | % |
| Gasoline | 19.7 | 47% |
| Diesel/Home heat | 8.4 | 20% |
| Jet Fuel | 4.2 | 10% |
| Lubricants/wax/... | 4.2 | 10% |
| Boiler Oil | 2.9 | 7% |
| Asphalt | 1.3 | 3% |
| Chemicals | 1.3 | 3% |
5 Polyethylene Synthesis
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Polymers typically contain between 50-100,000 monomer units.
6 Polymer Properties
7 Degree of Crystallization
Higher degrees of crystallization give rise to more rigid, higher melting plastics.
8 Heat and Crystalline Structure
9 Polyethylene Properties
- Long (spaghetti-like) strands
- ``No'' attraction between strands
- Arrangement gives varying crystallinity
- ``Necking'' or processing orients strands
10 HDPE
High-Density Polyethylene
- High molecular weight (n @ 10,000)
- Little branching
- Higher melting point than LDPE (130 ° C).
- Dishwasher-safe
- Uses:
- Milk and water jugs, gasoline tanks, cups, ...
11 LDPE
Low-Density Polyethylene
- Low molecular weight (n @ 500)
- High-degree of branching
- Lower melting point than HDPE (100-125 ° C)
- Lower strength
- Uses:
- Plastic bags, toys, electric insulation, ...
12 Polyolefins
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| Monomer | Name | Uses |
| CH 2 =CHCl | PVC | Pipes, ... |
| CH 2 =CH-C 6 H 5 | Polystyrene | Styrofoam, ... |
| CH 2 =CH-CH 3 | Polypropylene | Bottle caps, ... |
| CF 2 =CF 2 | Teflon | Non-stick coating, ... |
13 Condensation Polymers
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14 Polyethylene Terphthalate
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Uses:
- Clothing, soft drink bottles, videotapes, ...
15 Nylon
Uses:
- Clothing, ...
16 Modifying Polymer Properties
Your text lists six strategies for modifying polymer properties
· Vary chain length
· Vary 3D arrangement of solid
· Change degree of branching
· Modify composition of monomers
· Alter bonding between chains
· Change orientation of monomers within chains
17 Tacticity
Arrangement of individual monomer units in polymer may vary
- -(CH 2 -CH Cl)-(CH 2 -CH Cl)-(CH 2 -CH Cl)-
- Head-to-tail
- -(CH 2 -CH Cl)-(CH Cl-CH 2 )-(CH 2 -CH Cl)-
- Head-to-head
- Random arrangment also possible
- Typically gives rise to more flexible material
18 Recycling
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19 Density
| Polymer | Density | Comments |
| PP | 0.90-0.91 | |
| LDPE | 0.92-0.94 | Floats on water |
| HDPE | 0.95-0.97 | |
| PS | 1.05-1.07 | |
| PETE | 1.38-1.39 | Sinks in water |
| PVC | 1.18-1.65 |
20 Recycling Costs and Benefits
Pro
- Less crude oil required
- Less landfill space required
- Recycling chemistry still not ``ideal''
- Burning plastic generates energy
21 Paper or Plastic?
| Paper | Plastic |
| Renewable source | <3% of crude oil used |
| Biodegradable | Less space |
| ``Safer`` | Cheaper |
| Technology ``works`` | Less energy to produce |
File translated from TEX by TTH, version 3.02.
On 18 Mar 2002, 17:12.