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How can different types of polymers be identified, classified, and sorted…
How can different types of polymers be identified, classified, and sorted based on their physical and chemical properties, in order to improve recycling processes and reduce environmental impact?
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Variables
Independent Variable:
Physical Properties: Density, melting point, boiling point, tensile strength, surface area
CHOSEN INDEPENDENT VARIABLE: Types of polymers. This includes thermosets and thermoplastics. Using different types of polymers will allow us to identify the similarities in chemical properties and then they can be classified into groups.
Chemical properties: Reactivity, flammability, radioactivity, acidity, oxidisation state
Dependent Variable:
CHOSEN DEPENDENT VARIABLE: Melting point. This was chosen due to its relevance and high applicability in recycling processes, because polymers generally have melting points at around 200 degrees Celsius which can be melted fairly easily. A Bunsen burner can successfully melt polymers in a lab as well, meaning the polymers can be reformed and recycled into new shapes.
Controlled Variables:
Since the melting point is the chosen independent variable, all other variables must remain controlled and constant so that they do not impact the data. One controlled variable is the amount of thermoplastics designated for melting, because a too large amount can cause the liquidating to become slower. Another is the type of flame on the Bunsen burner; the blue flame should be used consistently across all groups so that the temperature applied to the polymers are the same.
Recycling Process
Mechanical
The polymers are sorted based on their compositions. They are then cleaned and shredded into small pieces. Next, the polymers are melted and are able to be reformed into new products.
Chemical
Depolymerisation: Breaks down the polymers into their smaller monomer pieces using chemical reactions or heat
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Risk Assessment
Melting substances can be very dangerous due to high temperatures, which can harm the conductors of the experiment. Because of this, an apron, glasses and heat resistant gloves is necessary.
Melting substances would require Bunsen burners. This means that proper processes are needed to use them, such as starting on the red flame and changing it to the blue flame for increase heat. Heatproof mats would prevent the Bunsen burner from causing damage to the lap equipment.
Classifications
Thermoplastics: softened when heated and solidifies when called. They can be recycled easily because they can be remolded. This is because their long polymer chains have weak bonds and so can be broken down easily.
Thermosets: formed permanently by hardening resin through curing. Curing can be caused by heat, high pressure or radiation. They cannot be melted back down and so do not have high recyclability. This is because the curing process causes them to have strong network structures which are resistant to heat and other chemicals.
Classifications: Identifying the key characteristics of polymers and then sorting them into categories. Thermoplastics and thermosets are two types of classifications of polymers.
Thermoplastics: Polyethylene, polypropylene, polyvinyl chloride, polystyrene, and nylon
Thermosets: Epoxy, polyurethane, phenolic, and silicone
Limitations and Errors
Sample size: the variety of polymers available to melt is not too many. Because of this, the sample size of polymer melting points might be low. Additionally, they could have varying purity which cause there to be different melting points in the same mixture.
Classifications: since thermosets cannot be melted, they can be easily identified but the exact structure and chemical compound would be unknown. In contrast, thermoplasts have larger differences in melting points and so chemical property variations are more distinct.
Human error: human errors can occur unintentionally, potentially due to a misuse of equipment. For example, the thermometer might have not been placed in the melting chamber long enough, meaning that the recorded temperature is invalid.
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