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Polycarbonate - Materials Cycle

Lab 11 - ENGR 45 - Chabot College
by

John Tumath

on 9 December 2015

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Transcript of Polycarbonate - Materials Cycle

Raw Materials
Synthesis and Processing
Engineering Data
Product Design and Applications
Waste
Recycle / Reuse
Density: 1.20–1.22 g/cm3
Melting Point: 155 °C
Elastic Modulus: 2.0–2.4 GPa
Tensile strength: 55–75 MPa
Compressive Strength: >80 MPa
Ductility: 80–150% elongation at break
Thermal Conductivity:
0.19–0.22 W/(m·K) @ 25 °C

Mechanical Properties
Electrical Properties
Surface Resistivity:
1015 Ω/sq (High Resistance)

Permittivity (e): 2.568 × 10−11 F/m

Permeability (μ) at 1 MHz:
1.089(2) μN/A2

Recyclability
It’s fully recyclable.
Polymer resin code #7
Material Cost
2.8 – 3.0 $/kg
Applications Using PC
Head lamp lenses
Dashboards
Interior cladding
Electronic component housing
Mobile phones
Battery boxes
CDs and DVDs
Traffic Lights
Many, many more!
Intended Shelf Life
Shelf life varies greatly by product due to storage conditions estimated by the manufacturer. Most range from a minimum of
two years
to a maximum of a 10 to
15 years
for some greenhouse panels.
Factors that shorten life of Polycarbonate:
Elevated humidity reduces the compressive strength and weakens the material.
Ultra-violet light will cause the plastic to become brittle and degrade.
Concentrated Acids
Aromatic Hydrocarbons
Halogens/Ketones
The main polycarbonate material is produced by the reaction of bisphenol A (BPA) and phosgene COCl
2. The overall reaction can be written as follows:
BPA Toxicity
Bisphenol A (BPA) is a key monomer required to produce polycarbonate.
It 1997 it was first shown that the adverse effects of low-dose exposure of BPA on laboratory animals. Bisphenol A is an endocrine disruptor that can mimic estrogen and has been shown to cause negative health effects in animal studies.
https://en.wikipedia.org/wiki/Bisphenol_A#Health_effects
BPA is was, and still is, used in a wide variety of food packaging so there has been much debate on the subject in the recent decade.
In 2012 the FDA banned the use of BPA in baby bottles as infants are seen as the only vulnerable group. The Environmental Protection Agency (EPA) holds the position that BPA is not a health concern.
As the old saying goes, the Jury is still out on this one.
Polycarbonate (PC) process using phosgene,most currently used
Manufacturing / Re-Manufacturing Process
About
2.7 million tons
of polycarbonate are produced annually worldwide.
Material Cycle: Polycarbonate
John Tumath and Chris Khone
The production of plastic begins with a distillation process in an oil refinery
The distillation process involves the separation of heavy crude oil into lighter groups called fractions. Each fraction is a mixture of hydrocarbon chains (chemical compounds made up of carbon and hydrogen), which differ in terms of the size and structure of their molecules. One of these fractions, naphtha, is the crucial element for the production of plastics.

Oil and Refinement
Hazards of Oil Production
https://en.wikipedia.org/wiki/Environmental_impact_of_the_petroleum_industry
Hazards of oil production include:

Leaking crude oil (oil spills) into the environment during recovery or during transportation.
Climate Change - Dependency on crude oil has shown a drastic affect on world weather patterns.
Cancer - Crude oil and many of its byprocuts are carcinogenic by nature and contact with animal life is extremely hazardous.
And many more negative effects.
Polycarbonate waste, like all other plastic waste, is a serious environmental issue. Here's some statistics:
Plastic constitutes approximately 90 percent of all trash floating on the ocean’s surface, with 46,000 pieces of plastic per square mile.
We currently recover only
five percent
of the plastics we produce.
The average American throws away approximately
185 pounds
of plastic per year.
Plastic accounts for around 10 percent of the total waste we generate.
The Great Pacific Garbage Patch is located in the North Pacific Gyre off the coast of California and is the largest ocean garbage site in the world. This floating mass of plastic is twice the size of Texas, with plastic pieces outnumbering sea life six to one.
Unlike other plastics, Polycarbonate can biodegrade somewhat in the ocean. However this process releases the toxin BPA into the environment. One team analyzed sand and seawater from more than 200 sites in 20 countries, mainly in Southeast Asia and North America. All contained what was described as a“significant” amount of BPA, ranging from 0.01 parts per million (ppm) to 50 ppm. They concluded that polycarbonates and epoxy resin coatings and paints were the main source.
Hundreds of Years
Polycarbonate is completely recyclable. After collected and sorted it is processed and cleaned into small pellets that can then be chemically reclaimed to make new PC. In reality, very little, plastic is actually recycled. Low national plastic recycling rates have been due to the complexity of sorting and processing, unfavorable economics, and consumer confusion about which plastics can actually be recycled. This applies even more so to PC as it is more difficult to recycle.
Recycled PC may show lesser resilience and has reduced impact resistance when compared to newly manufactured PC. Addition of fillers and pigments may reduce the resilience of the plastic. Chemicals can be used to improve impact resistance in recycled polycarbonate and they could be used for most of the applications that virgin polycarbonate is used.

Recycled PC finds applications in manufacture of plastic profiles. They have good stiffness, impact resistance, toughness and are transparent. These profiles have a high colorability with a lovely gloss finish that can imitate metal and glass.
Unlike most thermoplastics, polycarbonate can undergo large plastic deformations without cracking or breaking. As a result, it can be processed and formed at room temperature using sheet metal techniques.

Main transformation techniques for polycarbonate resins include:
extrusion into tubes, rods and other profiles including multiwall
extrusion with cylinders into sheets and films which can be used directly or manufactured into other shapes using thermoforming or secondary fabrication techniques, such as bending, drilling, routing, laser cutting etc.
injection molding into ready articles

Transformations
PC, like all other plastics, undergo a long chemical process to produce the material. This gives a lot of latitude to make small changes to adjust the properties of the final product, adding strength, ductility, color or any other property they want to enhance or mitigate.

The diagram to the left shows how the ingredients are placed into a reactor tank with various additives, catalysts and other chemicals that get processed into the raw polycarbonate pellets used in a wide variety of products.
Selling price for PC to a recycleer:
$0.22 USD/lbs as of 12/2015
Annotated Bibliography:
Thanks for Watching!
Alternatives
Polycarbonate is a very specialized material that
is extremely customizable to suit a variety of products. While many of its unique properties could be replicated by other plastics or other materials, none currently would have the combination that makes this material so attractive (hardness, electrical resistivity, etc)
Biodegradable PC is currently one alternative that is being researched. It would have all the properties of PC but would be able to be decomposed by bacteria, allowing it to be more eco-friendly.
Data, Technical, and February 2015. 3M TM Clear Polycarbonate Carrier 2703 (n.d.): n. pag. Web.

"Explaining Ductility Loss in Steam-Sterilized Polycarbonate." MDDI RSS. N.p., n.d. Web. 09 Dec. 2015.

Paper, A. Ul White. The Life Cycle of Materials in Mobile PhonesThe Life Cycle of Materials in Mobile Phones (n.d.): n. pag. Web.

"Polycarbonate Recycling - How Is Polycarbonate Recycled?" Plastic Expert. N.p., n.d. Web. 09 Dec. 2015.

"Is the Plastic Used in Knee and Hip Implants Safe?" BoneSmart. N.p., n.d. Web. 09 Dec. 2015.
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