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PLASTICS
- Differentiate between each of the following
- Monomer and Polymer
A monomer is a single atom, small molecule, or molecular fragment that, when bonded together with identical and similar types of monomers, form a larger, macromolecule known as a polymer.
- Thermoplastics and thermosetting plastics
Thermosetting plastics and thermoplastics are both polymers, but they behave differently when exposed to heat. Thermoplastics can melt under heat after curing while thermoset plastics retain their form and stay solid under heat once cured. Because thermoplastics have a low melting point, they are ideal for applications that use recycled materials. Thermoset plastics, in contrast, are able to withstand high temperatures without losing their shape, making them more durable.
- (a) State five properties of plastics
Plastic is a synthetic material created from a broad range of organic polymers that have become an indispensable part of our everyday world. The properties of plastic are numerous. For the most part, they are:
- Lightweight with a high strength-to-weight ratio
- Can be manufactured inexpensively and mass produced
- Water resistant
- Shock resistant
- Thermally and electrically insulating
- Define the term additives as used in plastic manufacture
Plastic additives are materials added during the manufacturing process that provide the optimal performance of the material when molded and put into use. Plastic additives can also be used to modify the characteristics of the polymer to achieve a certain performance from the plastic for a specific purpose.
During the plastic compounding process, additives, which are chemicals that help to modify the plastic, are combined with basic, raw plastic material to achieve color, property and performance requirements.
Plastic additives help to protect polymers in functional use from many of the elements we see everyday, guarding against extreme weather conditions and exposure from UV light or water. Additives can also provide protective characteristics. This includes features like flame retardancy, which is useful with polymer applications used in aircraft, leisure craft, electrical, network and junction boxes.
- List two examples of additives used in manufacture of plastics
The most commonly used additives in different types of polymeric packaging materials are: plasticizers, flame retardants, antioxidants, acid scavengers, light and heat stabilizers, lubricants, pigments, antistatic agents, slip compounds and thermal stabilizers.
- State two uses of polyamide (nylon)
Polyamides (or nylon) are considered high-performance plastics. They exhibit high temperature & electrical resistances. They find their use in the automotive, transportation, consumer goods, and E&E industry.
- Name two types of natural plastics
Plastics are made from natural materials such as cellulose, coal, natural gas, salt and crude oil through a polymerisation or polycondensation process. Plastics are derived from natural, organic materials such as cellulose, coal, natural gas, salt and, of course, crude oil.Naturally occurring polymers include tar, shellac, tortoiseshell, animal horn, cellulose, amber, and latex from tree sap.
- State two sources of synthetic materials used in making synthetic plastics
Synthetic plastics are derived from petroleum., natural gas or coal. Whilst biobased plastics come from renewable products such as carbohydrates, starch, vegetable fats and oils, bacteria and other biological substances.
- Give two functions of plasticizers in polymerization process
Plasticizers are low molecular weight substances added to a polymer solution to promote its plasticity and flexibility. Therefore, the plasticizers make the polymer solution more suitable for the application of film coating. There should be chemical similarities between the polymers and its plasticizers.