The different between Thermoplastics and thermal setting plastics
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PRIMARY DEGREE
Instelling
KITWE COLLEGE OF EDUCATION
Boek
Handbook of Thermoset Plastics
Plastics is the term commonly used to describe a wide range of synthetic or semi-synthetic materials that are used in a huge and growing range of applications. Everywhere you look, you will find plastics. We use plastic products to help make our lives cleaner, easier, safer and more enjoyable. We f...
Explain what happens when a ray of light passes from air into glass then water.
Antwoord: Glass and water are denser medium then air, so when light ray pass from air to glass and glass to water. Ray will bend towards the normal. So Angle of refraction is less than the angle of incidence. What happens is that light slows down when it passes from the less dense air into the denser glass or water. This slowing down of the ray of light also causes the ray of light to change direction. It is the change in the speed of the light that causes refraction
2.
What is the purpose of the construction in the thermometer.
Antwoord: In this condition if the thermometer is placed under the tongue or under the arms, the temperature and consequently the volume of the thermometer increases.
3.
Advantages and disadvantages of using alcohol and mercury for thermometer.
Antwoord: Alcohol
Advantages Disadvantages
Lower freezing point (-114 C) Less durable (alcohol evaporates)
Larger coefficient of expansion Alcohol can polymerise
Mercury
Advantages Disadvantages
Cheap display is harder to read
Accurate does not work below -39 C (Hg freezing pount)
4.
The kelvin temperature of a liquid is 300k. What is the temperature in degree Celsius?
Antwoord: K − 273.15 = °C
300k – 273
27 °C
5.
What are letters GK, GS, WA, AD, GA, GD and C in the games of netball stand for?
Plastics is the term commonly used to describe a wide range of synthetic or semi-synthetic materials that
are used in a huge and growing range of applications. Everywhere you look, you will find plastics. We
use plastic products to help make our lives cleaner, easier, safer and more enjoyable. We find plastics in
the clothes we wear, the houses we live in, and the cars we travel in. The toys we play with, the
televisions we watch, the computers we use and the DVDs we watch all contain plastics. Therefore, this
academic paper of writing will discuss on Thermoplastics and thermal setting plastics.
Plastics are versatile and flexible materials and they may be very suitable for use in your project. This
may be an area of materials research that you need to investigate in detail. It is important that you read
the information below and consider the type of plastic that will best suit your project. All plastics are
based on polymers and they are created by bonding molecules together. The terms monomer and
polymer are very important in the plastics industry. A monomer is a relatively small molecule that can
chemically bond to other monomers, forming a polymer. Remember, all plastics are polymers. A
MONOMER is a small molecule that combines chemically to other monomers to form a polymer
Example - derived from oil - a hydrocarbon ethylene molecule (seen opposite). Many modern plastics
are manufactured from oil. An ethylene monomer forms a’ long chain monomer’ due to individual
ethylene monomers joining together. This produces the polymer - polyethylene. This is a thermoplastic
and is useful in the manufacture of 'plastic' bottles.
Once 'set' these plastics cannot be reheated to soften, shape and mould. The molecules of these plastics
are cross linked in three dimensions and this is why they cannot be reshaped or recycled. The bond
between the molecules is very strong. These plastics can be re-heated and therefore shaped in various
ways. They become moldable after reheating as they do not undergo significant chemical change.
Reheating and shaping can be repeated. The bond between the molecules is weak and become weaker
when reheated, allowing reshaping. Thermoplastics tend to be composed of 'long chain monomers'.
These types of plastics can be recycled Thermoplastics can be differentiated from the thermoset
materials, They are the organic materials that melt when they are heated, They can be remelted back into
the liquid, They are formed when they are in the melted or viscous phase, They are heated, formed &
cooled in their final shape, whereas the thermoset plastics remain in the permanent solid state.
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, Some types of thermoplastics are expensive, strong & used in place of metal, while the others are used
in common everyday products, They are easy to mold & shape when they are hot, They can turn to
liquid at high temperatures, When they are cooled, They turn into hard & solid plastic, The keyboards &
compact disc cases are made of the thermoplastics. (Otaga, 2009)
The most popular methods of processing thermoplastics are injection molding, extrusion, and
thermoforming, The thermoplastics can be like rubber or as strong as aluminum depending on their
chemistry, They are light weight, Some thermoplastic materials can withstand the temperature extremes
up to 600 F, while the others retain their properties at -100 F.
Some thermoplastic materials have no known solvents at room temperature, The thermoplastic
composites can be made to be electrically conductive with the addition of carbon or metal fibers, The
combination of light weight, high strength & low processing costs make the thermoplastics well suited
to many applications, They are used as thermal insulators & electrical insulators.
Two types of thermoplastics are high-temperature thermoplastics and engineering thermoplastics,
Examples of high-temperature thermoplastics contain popular materials such as polypropylene and PVC,
They are commonly used for the pipes, the bottles & the plastic containers.
Engineering thermoplastics are typically flame-retardant & they can withstand the temperatures of up to
100° C, Engineering plastics cost much more to produce than these popular materials, They contain the
materials such as the nylons and the polyesters. (Otaga, 2009)
One type of the thermoplastic which is called polyester resin, It is used for the car bodies and the garden
furniture, Another type of thermoplastics is polymethyl methacrylate, It is used for the lenses and the
windows.
Thermoplastics advantages
Thermoplastics are energy efficient both in their manufacture & processing, Thermoplastic components
can be made in very high volume with high precision & low cost, They can replace the metals with
considerable weight savings, proper care is taken in design, Most thermoplastics have better properties
than the metals and they can tolerate larger deflections than the metals without deforming.
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