DT Plastics
- Created by: Anil_Singh
- Created on: 08-10-16 16:17
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- Plastics
- 3 main types of plastics(Polymers)
- Thermoplastics
- These materials can be repeatdly reheated and re-moulded
- Structure- Have a tangle of long-chain molecules held together by strong electrostatic forces
- Elastomers
- These are polymers that have a good elasticity, i.e they can be distorted under pressure but will return to original shape.
- Structure- Have long chain molecules like coils whihc spring giving it elastic properties
- Thermo-setting plastics
- A chemical change results in them becoming permenantly rigid i.e cannot be re-heated/reshaped
- Structure- coonsist of long chain molecules but differ in thath they ar eheld together by rigid cross-links making them permanently rigid
- Thermoplastics
- Introduction
- Plastics are a group of materials made up of a long chain of molecules. Mostly hydrocarbons(hydrogen and carbon atoms only)
- Plastics are becoming more popular than other materials because of its benefits(lightweight, self-colored/finished, electrical and thermal insulator).
- General properties of plastics
- +They are good electrical/thermal insulators
- +They have a good strength to weight ratio
- +Good atmospheric and chemical corrosion resistance
- Improving the properties of plastics
- Fillers-Fill in plastic reducing bulk and price
- Flame-Retardants-Reduces the risk of combustion
- Anti-static agents-Reduce the effects of static charges that could build up on a product
- Plasticizers- added to increase plasticity and flexibility to reduce brittleness
- Stabilisers-used to reduce the effects of UV light , by breaking down sunlight
- Sources of plastic
- Animal and vegetable by products-are used to manufacture some synthetic polymer plastics. E.g Cellulose(plant fibre)
- Coal, oil and gas- Most purely synthetic plastics
- Biodegradab-e Plastics-Conventional oil plastics don't biodegrade. Thus biodegradea-le plastic are designed to degrade in correct conditions
- Applications-vary widely mainly packaging: shopping bags, food trays,soft drinks bottle, disposable items, gardening, medical, sanitary products
- PHAs and PHBs-Biodegradabl-e plastic polymers are created naturally using bacteria to aid in fermentingplant sugars forming PHA. The most popular type is PHB
- Oxo-degradable polymers-Have additives that promote short degradation time e.g. less than five years.
- 3 main types of plastics(Polymers)
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