User:Cstrin2/sandbox

Increasing Usage
K-Cup consumption has increased dramatically since its inception. Approximately 13% of the adult population of the United States drinks coffee made from a brewing system, and there are more than 12.5 million Keurig brewing systems in the U.S. This leads to K-Cup sales accounting for 26% of ground coffee sales in the U.S. in 2013, and more than 8.3 billion individual K-Cups being produced in 2013.

K-Cup Construction and Recycling Issues
K-Cup pods are composed of four components : Polystyrene is used as an outer layer due to its heat formability and barrier properties. EVOH is used as a gas barrier and to prevent chemical flow-off from the other plastics under heating. Polyethylene is used as a heat seal layer and a moisture barrier.
 * the plastic container, made of a polystyrene/EVOH/polyethylene polymer blend.
 * a paper filter, fused to the inside of the plastic container.
 * an aluminum foil lide attached to the top of the plastic container.
 * the organic material inside the container

Except for the #7 plastic container, each of these components are able to be recycled individually. However, due to the fact the used K-Cups are typically disposed of as a whole unit, they are non-recyclable. Their small size also leads to them being easily overlooked in processing facilities and ending up in glass or mixed-paper recycling streams. This leads to many used K-Cups finding their ways to landfills each year.

K-Cup Degradation
Once in the environment, K-Cups generally do not degrade quickly due to the structure of the polymers from which they were made; these plastics are designed specifically for their stability and durability. However, over time, they can be degraded; this occurs primarily by photodegradation and thermooxidative degradation. The general mechanism involves UV light as the activation source for the incorporation of oxygen atoms to the polymer, producing peroxy radicals. These peroxy radicals produce hydroperoxides, which lead to the production of hydroxide free radicals. The hydroxide radicals bind the polymer and cause chain scission, resulting in increasingly smaller molecular weight chains. These small plastic molecules are typically either degraded by microorganisms or leached into the environment. However, due to the low oxygen availability and low levels of sunlight penetration in landfills, this entire process can take 50 years or more.

Polystyrene Degradation
Polystyrene undergoes photooxidative degradation by first absorbing UV light, producing polynytryl and hydrogen radicals. The polynytryl radicals react with oxygen molecules to produce the peroxy radical. Upon further UV absorption, hydroxide and carbonyl radical compounds are produced. Intramolecular chain scission following, resulting in a carbonyl compound and a Polystyrene polymer of reduced molecular weight.

Ethylene Vinyl Alcohol Degradation
EVOH is formed by the polymerization of ethylene and vinyl acetate, followed by hydrolysis. Because of this, EVOH is a hydrophobic copolymer, so under wet condition the vinyl alcohol hydroxide groups are converted to carbonyl groups with double bonds. This transformation reduces the intermolecular hydrogen bonding strength of the molecule, resulting in lower molecular cohesion and eventual polymer breakdown.

Polyethylene Degradation
Polyethylene undergoes photooxidative degradation in a similar manner to Polystyrene. Absorption of UV light produces two alkyl radicals, which will react with oxygen to produce a peroxy radical. This peroxy radical becomes a hydroperoxide after addition of hydrogen atom, and further reaction with light leads to a carbonyl radical and a hydroxide radical, which leads to chain scission and production of a carbonyl end group and lower molecular weight polyethylene polymer.

Microplastics in the Environment
The most pressing problem associated with the environmental degradation of the polymers used in K-Cups is the formation of microplastics. Once these polymers are degraded to under 1 mm in diameter, they are referred to as microplastics. These microplastics pose an environmental threat, particularly when they are leached into aquatic environments via rainwater. They have been shown to transport persistent organic pollutants (POPS) such as polychlorinated biphenyls, organochlorines, polyaromatic hydrocarbons, and nonylphenols. These pollutants are either absorbed from the environment or are present as part of the plasticizer additives of the polymers. Ingestion of microplastics has also been shown in filter feeding aquatic creatures such as mussels and worms, which could lead to internal damage of the organism or absorbance of the toxic compounds transported by the microplastics.

Keurig Green Mountain's Efforts for Increased Sustainability
Keurig Green Mountain has VUE brewing systems available, which utilize recyclable #5 plastics in their coffee pod construction. They also have reusable K-Cup containers. Long term, Keurig Green Mountain has set 2020 as the target date for which they intend all K-Cups to be 100% recyclable. They plan to accomplish this by replacing the non-recyclable hybrid #7 plastics used in the K-Cups today with fully recyclable #5 plastics, as well as finding ways to make separating the components of K-Cups for recycling easier. They also intend to offer more programs nationwide for the responsible disposal of K-Cups.