Unit A Flashcards
How are synthetic plastic polymers different from natural plastics?
Natural polymers are common and produced by living organisms. Synthetic polymers are not found in nature since they are produced in laboratory or manufacturing environment that are mostly made from petroleum and other fossil fuels.
Please list the seven basic types of plastics and provide a brief description of each that highlights a unique or identifiable descriptor of the polymer.
Polyethylene (PE): the most common plastic on earth manufactured in varying densities with each density giving unique physical properties.
Polypropylene (PP): second most produced synthetic plastic. It is a moldable plastic, so it is durable, flexible, heat resistant, acid resistance, and cheap. It is stronger than PE.
Polyvinyl Chloride (PVC): third-most produced synthetic plastic polymer that can be manufactured into either foamed or rigid form of PVC. Adding plasticizers creates a softer and more flexible form of PVC that can be used in plumbing products, electrical cable insulation, and other similar products.
Polyethylene Terephthalate (PETE or PET): fourth-most produced synthetic plastic that has chemical resistance to organic materials and can be easily recyclable.
Acrylic or Polymethyl Methacrylate (PMMA): typically used in a sheet form used as a lightweight, shatter-resistant alternative to glass so it can be used to create products such as mirrors and plexiglass. It is 17 times more impact resistant than glass and it is easier to handle and process.
Polycarbonate (PC): an engineered plastic that is clear as glass but 250 times stronger. It is also 30 times stronger than acrylic. The strength allows it to be strong, impact-resistant, and design flexibility. It is used in products including greenhouses, DVDs, sunglasses, and police riot gear.
Acrylonitrile-Butadiene-Styrene (ABS): it has a low manufacturing cost used in automotive and refrigeration industries that is robust, glossy, highly processable, and impact resistant. It is used in products such as boxes, gauges, protective headgear, luggage, and children’s toys.
What are the three taxonomic schemes for classifying plastics?
The three taxonomic schemes for classifying plastics are response to heat, carbon source for the polymer, and biodegradation.
Please compare and contrast thermoplastics and thermosets.
Thermoplastics can melt and re-melt making them potentially recyclable unlike thermosets cannot be re-melted which makes recycling challenging.
What are the polymer carbon sources for plastics? Which is used for the majority of plastic production?
The polymer carbon source is either fossil or biogenic. Most plastic production uses fossil-based such as petroleum or natural gas.
Why are NatureWorks PLA and Coca-Cola’s original PlantBottle not necessarily good substitutes for traditional plastic polymers?
NatureWorks PLA isn’t good substitute since it doesn’t solve the actual breakdown of plastics to become shorter since PLA has a slow degradation rate. With Coca-Cola’s original PlantBottle while it achieves the use of bio-based resources however it can run into other challenges such as resource availability and recycling infrastructure.
What is biodegradation and why is it not the solution to plastic waste?
Biodegradation is the complete breakdown of microbial activity material into CO2, H2O, and other constituents involving a complex process that depends on many factors such as temperature, moisture level, and specific microbes. This isn’t a solution to plastic waste since the rate can vary from weeks to year to decades.
Create a brief historical timeline for plastics.
1600 B.C.: Olmecs made rubber balls from latex from indigenous rubber trees mixing it with juice.
1500s: Rubber exported from tropical zones to sites to Mesoamerica.
1850s: first human-made polymer (not fully synthetic) by Alexander Parkes
1869: Patented a solid, stable nitrocellulose known as Celluloid; becoming the first commercially successful human-made polymer
1872: PVC was accidentally discovered by Eugen Baumann, a German chemist.
1907: Leo Baekeland invented and patented the first completely synthetic polymer
1920as: plasticizers were used in PVC to make them softer and more flexible creating the first modern plastic
Early 1940s: plastic production increased due to shortages of other materials during WWII
1950 to 1970: growth rate of global annual plastic production was 15%
In terms of annual plastic production, why are there only three years where annual plastic production decreased relative to the previous year?
Those three years where annual plastic production occurred were due to the fact it coincided with three major economic crises: two major oil crisis and the great recession.
In reality, almost all modern plastics are produced from what starting material? What evidence is that that this is correct?
Most plastics are made with petroleum and natural gas as the starting material. The evidence of the product of the material, primary plastics that makes polyethylene (LDPE, LLDPE, and HDPE) and polypropylene (PP) which makes up of almost half of plastic global production at 45%.
What are the three largest plastic consumption sectors (1950-2017)?
The three largest plastic consumption sectors are packaging (36%), building and construction (16%), and textiles (14%).
What is the difference between pre-consumer and post-consumer plastic waste? Which is of greater concern? Why?
The main difference between both types of wastes is that pre-consumer plastic waste is easier to recycle than post-consumer waste. The greater concern is post-consumer plastic waste since most of the plastic waste comes from these post-consumer or end-of-life waste.
Please describe mechanical and chemical recycling. Why does plastic recycling have poor economics?
Mechanical recycling involves shredding or grinding waste, clean, decontamination, and re-compound into granulate. Chemical recycling is a pre-treat waste separating the monomers to then re-polymerized into the original plastic. Plastic recycling has poor economics as it is oftentimes contaminated with other materials, needs to be separated by polymer to be valuable, and it must compete with low-cost primary plastic.
Why does thermal destruction of plastics appear to be the only way to effectively deal with plastic waste? What are the negative outcomes from this technique?
Thermal destruction appears to be the only way to effectively deal with plastic waste since that waste does not biodegrade. The negative outcomes come with the impacts both on the environment and our health depending on the incineration technology, temperature, operation, and emission control technology.
Please describe the global recycling, incineration and discard rates. How does the USA compare to other countries?
Discarded rates over the past decades have been higher than both recycling and incineration rates however discarded rates are declining vice versa with recycling and incineration rates they are increasing. The USA compared to other countries have a smaller rate at 9% with recycling rate and 16% incineration rate.
