Polymers Flashcards
What’s the difference between thermosetting polymers, thermoplastics and composites.
Thermoset plastics undergo a chemical change and cannot be reheated and shaped where as thermoplastics can be reshaped by heat. Composites are made from multiple components.
4 examples of thermosetting polymers
Urea formaldehyde, epoxy resin, polyester and silicone.
3 examples of thermoplastics
Acrylic, high density polyethylene and polyethylene terephthalate.
2 examples of composites
Glass reinforced plastic and carbon fibre plastic.
Urea formaldehyde- properties and uses
High tensile strength, high heat-distortion temperature, low water absorption, mould shrinkage, high surface hardness, elongation at break, and volume resistance.
Adhesives, plug sockets, desk lamps and fabrics.
Urea formaldehyde- advantages and disadvantages
Low cost, ease of use under a variety of curing conditions, low cure temperatures, water-solubility, water-resistance, resistance to microorganisms and abrasion, hardness, excellent thermal properties and lack of colour.
UF can release formaldehyde, a potential carcinogen, especially when exposed to high temperatures. Low thermal stability – UF has a low glass transition temperature, which limits its use in high-temperature applications.
Epoxy resins- properties and uses
Resistant to chemicals, heat resistant, adhesion to variety of substances, high tensile compression and bend strengths. Low shrinkage, high electrical insulation and corrosion resistant.
Coating composites for electrical items and filling gaps in materials.
Epoxy resins- advantages and disadvantages
Help increase the lifespan of buildings by improving the durability of the structural parts, engineering adhesives and paints. Epoxy resins provide a protective layer that separates food and drinks from the metal used to make their cans.
Long curing time, messy application, potential harm to health, and higher cost compared to other adhesives.
Polyester- properties and uses
Strong , resilient and durable, resistant to shrinking and stretching, resistant to several chemicals. Dries quickly, can be recycled, resistant to abrasions.
Bottles, films, tarpaulin, sails (Dacron), canoes, liquid crystal displays, holograms, filters, dielectric film for capacitors, film insulation for cable, and insulating tapes.
Polyester- advantages and disadvantages
Strength, flexibility, moisture resistance, ease of care, and low cost.
High energy and water consumption, pollution, and inability to biodegrade.
Silicone- properties and uses
Fine electrical properties, good chemical stability and flame retardancy, and superior resistance to heat and cold.
Sealants, adhesives, lubricants, medicine, cooking utensils, thermal insulation, and electrical insulation.
Silicone- advantages and disadvantages
Last longer, spread better, stay flexible or rigid, and withstand extreme temperatures or humidity.
Tear strength meaning it is susceptible to breakage.
Acrylic- properties and uses
Strong, stiff, transparent and lightweight. Plus hard, durable and a good electrical insulator. Also has a good strength to weight ratio. Acrylic can withstand extreme weather and chemicals.
Acrylic can be used for shop signage or a glass substitute. Also in storage boxes and crates, car lights or CD cases.
Acrylic- advantages and disadvantages
Acrylic is easy to shape, highly transparent, easy to clean and maintain. It is also stronger than glass whilst being lighter, plus an affordable substitute. Acrylic is also 100% recyclable.
Brittle so it can easily break or scratch. Cracks are easily formed and acrylic is prone to splintering.
High density polyethylene- properties and uses
High density polyethylene has good impact strength and is resistant to chemicals. Due to its water barrier it can float and the products created from HDPE are very easy to maintain (easily washed). It’s a good electrical insulator and flexible.
HDPE is used for water tanks, water pipes, bowls, thin packaging sheets and household bottles for either edible items or chemicals.