Sustainable Exam 2 (Study Guide)

What is “Bakelite” and why is it important?

• first fully synthetic plastic

• Created to respond to the need of growing electrical industry for insulating  wires and other high voltage devices

• Combination of phenol and formaldehyde…a type of “resin”

pure polymeric material without any additives?

resin

most toxic polymer by synthetic pathway?

Polyurethane

A material is only called a plastic when it has ______?

otherwise, just a ________.

additive

polymer

What led to the rise of plastics in the middle 1900’s?

• WWII- nylon used for parachutes, ropes, body armor, etc

How was polyethylene discovered?

• the British Imperial Chemical Industries  were trying to combine ethylene and benzaldehyde and the experiment failed, but a new substance was discovered: Polyethylene

What was one of the first PE products created and widely distributed?

tupperware

What makes a polymer a plastic?

additives

what is considered the world’s most toxic chemical?

dioxin

What is an endocrine disruptor?

Causes reproductive and developmental problems

What kinds of additives are endocrine disruptors? (list)

• BPA

• Plasticizers

• Fire Retardants

• Dioxin

• Alkylphenols (UV stabilizers)

Why is plastic waste a good indicator of the Anthropocene Era?

• era of earth’s geological history  where almost everything is shaped by human activity: forests,  lakes, land mass, oceans, atmosphere etc.

• When geologists study our age in the future, the presence of  plastics may be the greatest indicator of the human activity

What are some common methods of plastic degradation in the environment?

• physical/mechanical: forces that shear, pulverize, and splinter

• chemical: thermal or UV breakdown

• biological: biodegradation by microorganisms

any small particles entering the environment are known as?

microplastics

what measurement qualifies as a microplastic?

1 mm-0.1 mm

What are some kinds of microplastic waste and how does it affect human health?

• Fibers, films, filaments, foams, fragments, granules, pellets, microbeads

• Can be endocrine disrupting in humans, as well as in water for animals/humans.

• It disrupt natural biocycles and nutrient cycles. Toxic chemical leaching from plastics.

What are some kinds of microplastic waste and how does it affect soil health?

Affect

• disrupts ability of soil to store carbon

• nitrogen and phosphorus nutrient cycles disrupted

• more GHGs emitted from soil

• disrupt natural microbial diversity and affect soil temps

What are some kinds of microplastic waste and how does it affect ocean health?

Types

• discarded nets

Affect

•Blockage / damming of natural water flows

•Become breeding ground for pests / mosquitos

•Source for leaching of toxic chemicals

•Disturbing natural biocycles, nutrient cycles

•MP ingestion and disruption of food chain

•Economic losses to tourism and fishing, economic development

How does plastic waste affect fish population?

disrupts the food chain when fish ingest microplastics

Is there a difference between pelagic and demersal fish populations and the kind of plastic they consume?

• Pelagic fish have higher counts and diversity of plastic waste in their stomachs than Demersal

• PE is most common polymer type

How is microplastic waste more harmful that macroplastic waste?

they have a greater SA and are able to absorb nutrients and toxins from the environment

How do microplastics affect soil / water / human systems differently?

What is the main difference between polyolefin and condensation polymers from a degradation viewpoint

condensation polymers are more easily degraded because they have other active groups whereas polyolefins are long chain hydrocarbons that make it difficult for anything else to bond/enter and degrade

What sustainability advantages do thermoplastic polymers have over thermoset polymers?

thermoplastic polymers are able to melt again after cooling therefore are able to be reused whereas thermoset polymers won’t melt again after curing, it’ll only degrade

What factors affect sustainability from a melt-processing standpoint?

• cheapest option

• mechanical recycling

• doesn’t often contain by-products that require disposal

• Lower melting points take less energy -> more sustainable

How does the crystallinity of PE affect its properties and therefore affect sustainability?

increasing crystallinity affects these properties:

• strength: incr

• stiffness: incr

• toughness: decr

• barrier: incr

• optical clarity: decr

• solubility: decr

increased crystallinity decreases sustainability bc more energy is required to break the C-C bonds

Lower crystallinity could be easier to melt down and reshape than the harder materials

Compare polyolefin and polyesters in terms of GHG and Energy Demand

polyolefin

• GHG: emissions come from electrical requirements

• Energy demand: comes from chemical feedstocks

polyesters

• GHG: higher than polyolefin

• Energy demand: more even split for demand and chemical feedstocks

What are the first generation and second generations of bio-PET “plant” bottles made of?

brazilian sugar cane

• first gen: sugar to bioethanol to ethylene glycol

• second gen: sugar to ethylene glycol

What advantages / disadvantages come with using sugarcane for plastic production?

• advantage: it has a high yield, chemically similar to its plastic counterpart

• disadvantage: not necessarily biodegradable, can have higher impacts than polyesters due to solvents and high temps for synthesis

Why are agricultural residues typically better as a feedstock than sugarcane / starch?

• The same additives are normally needed

• Energy and GHG emissions are normally similar

What are some sources for polymer production that are not food-based?

• animal fats

• cellulose

• chitosan

• tannins

• castor bean

Compare and contrast the biodegradability and manufacturability of PLA and PHA

• PLA: bacterial, not industrially compostable and recyclable, thermoplastic, less expensive manufacturing than PHA, degrades in 1-6 mo in a commercial facility

• PHA: bacterial, expensive to manufacture, home compostable

PLA vs PHA: Which can be blow molded?

PHA

-PLA has too low a melt-viscosity

PLA vs PHA: Which can be spun into fibers?

PLA

-requires high crystallinity

How do the barrier properties of PLA compare to other polyesters?

stronger than other polyesters

How is starch used to replace polyurethane foam?

Plasticizers are added to make is less brittle

What is “plasticization”?

• the process of adding a plasticizer to plastic to make it more pliable

• typically involves heating with water, glycerol, or sorbitol

what kinds of end of life scenarios are available for starch?

• Can be degraded or incinerated

How do closed cell foams help in the sustainability of buildings and insulating devices?

• the gas trapped in  cells is primarily responsible for insulating properties

• it is more difficult for air to travel through a closed cell foam as the cells convolute the path the air would take

What goes into a robust recycling program at the city-wide level?

• collection

• sorting

• reprocessing

• end markets

• consumer engagement

all steps must be engaged

what is a measure of how well a material maintains temperature on one side despite a change in temperature on the other?

r-value

What are some consumer motivations for recycling?

• altruistic: concern for planet

• legal: mandated recycling

  • ex: Switzerland

• deposit system

• economic: waste disposal more costly

What are motivations for businesses to recycle?

• economic?

• EPR

The amount of material diverted from the landfill?

diversion rate

The percentage of households participating in recycling program?

participation rate

The amount of municipal solid waste (MSW)  collected as a percentage of total waste generated?

collection rate

what is MRF?

material recovery facility

What are “bottle bills” and how does it affect recycling?

• these bills require a minimum refundable deposit on beer, soft drink and other beverage containers in order to ensure a high rate of recycling or reuse

• increase the recovery of plastic waste

Who is for and against bottle bills?

• aluminum and plastic recyclers are for the bill

• the american beverage association and plastic industry is against

  • say it doesn’t work and penalizes consumers

How does “extended producer responsibility” work?

• sets levels for recycling and waste recovery that forces companies to design their packaging to be recovered and recycled

• Fee is applied to each package created by the producer to pay for its eventual disposal or recycling

difference between primary recycling, secondary recycling, and tertiary recycling?

• primary: reuse, waste generated by producers that can be  inserted back into the manufacturing process

• secondary: mechanical, post-consumer waste

• tertiary: chemical, break-down of plastic waste to smaller molecules that can be used in open-loop or closed-loop applications

What are most plastic bottles turned into after recycling?

recycled fiber

What are some ways of using recycling material in food containers to avoid contamination? (4)

1. Use chemical recycling to create pristine plastic materials

2. Sandwich the recycled material between first generation material

3. Use a cleaner waste stream (like deposit bottles) that does not have  contaminants

4. Restrict recycled plastic to less sensitive applications like apples,  oranges, eggs, etc.

How does recycling compare to incineration and landfilling in terms of GHG emissions?

• 100% recycling (only) has lower GHG emissions than any combo of landfilling and incineration

• landfilling has lower GHG emissions than incineration

• when using a combo of recycling, landfilling, and incineration, the GHG emission levels are about the same

3 main types of chemical recycling

• pyrolysis

• solvolysis

• gasification

explain pyrolysis

• Using high temperatures (500-   1000C) in the absence of oxygen to break carbon chains

• Types: All plastics, more suited for polyolefins

• Many different products produced, can also produce fuels for energy production

• Can take mixed plastic waste but requires purification afterwards

explain solvolysis

• primary chemical recycling method

• The use of chemicals like water, methanol, or ethylene glycol to break down plastic to monomers

• More suited to condensation polymers like PET, polyamides, polyurethanes

• typically only get one product at the end

explain gasification

• Creates high energy density gases from   plastic waste like CO, H₂, and CH₄

• Mixed plastic waste is generally supported

• Products are used for energy production (syngas)

• obliterates plastic into gas

which recycling methods can take mixed plastic waste? (2)

pyrolysis and gasification

Discuss the debate regarding the use of the three main types of chemical recycling in recycling plastic waste

for

• Allows for infinite recycling of   plastic waste

• Lowers GHG emissions from petroleum feedstocks

• Diverts plastic waste from the landfill / ocean

against

• Introduces new waste streams and   chemical usage

• Is not really recycling, just a way to   justify continued plastic production

• Toxic additives from plastic waste are concentrated

• Chemical plants located in economically depressed areas

What is the mass balance approach to determining recycled content?

• a technique to track the amount of recycled material making its way into new products

• The amount of recycled content is calculated on a per molecule or per mole basis

• Chemical recycling requires these techniques because the actual recycled material is mixed with other chemical inputs

How is the Clean Air Act important from an incineration perspective?

• regulates the 9 most hazardous substances produced via incineration

• protects the human, water, and air health

• First Incinerator built in NY City in 1885, and hundreds built thereafter until the clean air act in the 60’s

What are the pros / cons of using incineration?

pros

• Huge reduction in volume/mass of waste

• Ash after burning is not toxic/biohazardous

• Controls exist to remove toxic   substances from air

• Energy is produced reducing cost

cons

• Other fuels are needed to start and maintain combustion

• There still are GHG and other emissions to airways

• Price of energy generation is more expensive

• Not all waste is combustible

• Long lead times to startup incinerators to respond to energy demand in grid

How do you create energy from incineration?

1. Most common burning method is “stoker-type” where a set of inclined moving grates are used to completely combust waste

   1. Waste is agitated and mixed with excess of air to induce complete combustion

   2. The hot gasses produced (“Flue Gas”) is directed to boilers where superheated steam is produced to move turbines in the production of energy

2. Flue gas is the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases; it’s how energy is produced in an incinerator

   1. Ash content also decreases energy production and requires additional waste disposal

What is “flue gas”?

• the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases

• it’s how energy is produced in an incinerator

What is the significance of the ash content?

can decrease energy recovery/production in combustion and requires additional waste disposal

What are some of the challenges of using incineration to produce electricity?

• Moisture decreases energy recovery per kg.

• Ash content decreases energy   production and requires additional waste disposal

• Long lead times to startup incinerators to respond to energy demand in grid

Use the “Waste Mining Method” to calculate the GHG’s associated with the first lifecycle of plastic production if it is assumed that 50% of waste is recycled

*refer to notes*

Calculate the GHG’s associated with the second lifecycle:

*refer to notes*