Back to: Basic Technology JSS 1
Welcome to class!
In today’s class, we will be talking about rubber and plastic. Enjoy the class!
Rubber and Plastics
Rubber is a polymer with the property of elasticity. There are two categories of rubber: natural rubber currently obtained from the rubber trees, or and synthetic rubber derived from petrochemicals.
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.
Types of rubber
The natural rubber also called India rubber and gum rubber. A tap is inserted into the tree, and liquid latex drains into collection containers. It is known for its durability and resistance to extreme temperatures. It is elastic, flexible, and has resistance to degrading, abrasions, and surface friction
Neoprene rubber, also known as chloroprene, is an older synthetic rubber. It is less susceptible to degrading, corrosion, and burning than most other synthetic and natural rubbers, so it is often used as a base material in corrosion-resistant coatings, high-pressure gaskets, belts, and adhesives. Its waterproofing and insulating qualities mean that it is often used for aquatic clothing, gear, and equipment.
Uses of rubber
It is very easy to imagine, as we know what is eraser from school times. If your eraser is nowhere to be seen, but you have a few rubber bands lying around, you can use them instead. All you need to do is to make a rubber band ball, for doing this, just wrap several rubbers around a golf or tennis ball and that is all. Now you can use this ball as an eraser.
Have you ever faced such problem as that awful brown colour of a fruit or vegetables? To prevent that, next time you slice up an apple, just put it back together, secured with a band and it won’t get brown then. It is a perfect way to save a product for later, if you are, for example, packing a lunch or dinner with apple slices.
We’re sure you know that feeling when someone has a heavy hand while using the products with a pump dispenser, for example, shampoo, hand soap, body lotion, conditioner etc. The rubber can help you in this situation. All you have to do is simply wrap a rubber band around the pump a few times, try to control how much comes out. And that’s it. Now you don’t have to spend more product than you need.
Tying up loose ends:
That’s the most common way to use the rubber. We are sure you know that, but let us still remind you. Just put one rubber band around the thing, which you think can be unravelled, for example, spools of ribbon, electrical cords or measuring tape. Lid gripper. And here is the solution to your troubles. You can simply wrap a wide rubber band around the rim of a lid and twist it. It will help you to open this jar.
A lot of people like parties. But the synonym to the word “party” is “a mess”. There are usually a lot of people, food, drinks, and the main problem in all that is the possibility to confuse what drink is yours. That’s the case when you can use a rubber band. Simply wrap one around your cup and you will always see where exactly your drink is.
Properties of rubber
- Tensile modulus
- Tensile strength
Now, let’s try to explain the properties stated above to the best of our knowledge
The chemical structure of the elastomers provides them with an inherent hardness that can be altered. The modified hardness is then measured in terms of durometer on a Shore scale.
Tensile strength is the amount of force needed to tear apart a rubber specimen until it breaks. It is also known as the ultimate tensile strength and is measured in terms of megapascals or pounds. The tensile strength is a key factor for designers and buyers as it signifies the point of failure resulting from the stretching of rubber.
Tensile modulus is the stress or force required for producing a strain or an elongation percentage in a rubber sample. Although it sounds similar to tensile strength, the properties are different. Harder rubber usually has a higher tensile modulus, making it more resilient.
Resilience, also known as a rebound, is the ability of rubber to return to its original size and shape following a temporary deformation, such as contact with a metal surface. It is critical in dynamic seals that serve as a barrier between stationary and moving surfaces.
Types of Plastic
Thermoplastics: Which are softened by heat and can be moulded. (Injection moulded, blow moulded or vacuum formed). Good examples are acrylic, polypropylene, polystyrene, polythene and PVC.
Thermosets: Which are formed by ha heat process but are then set (like concrete) and cannot change shape by reheating. Good examples are melamine (kitchen worktops), Bakelite (black saucepan handles), polyester and epoxy resins.
Uses of Plastic
- Polyester coated concrete by moulding from an existing plate.
- Sprayed polyurethane with sand and gravel agglomeration.
- Epoxy resins and polyesters on various supporting media
- PVC plasticized plates (spraying, coating or adhesive films)
- Polyester epidermis available as permanent shuttering
- Poly-methyl methacrylate
- PVC casing on metal moulding
- A polyester laminated sheet on wooden moulding
- Methyl polymethacrylate
- Polyester glass fibre and phenolic foam core
- PVC/ wood
- Sprayed lining polyurethane
- Laminate – Melamine and phenolic plastics – polyester
- Wall tiles – polystyrene, PVC – tiles or mosaic
- Asbestos plastic slabs (asphalt tile type)
- Homogeneous semi-flexible vinyl slabs
- Flexible, homogeneous or multi-layered vinyl slabs.
Properties of Plastic
The plastics are sufficiently strong and can be used for load-bearing structural members. Plastic as a structural material has not gained much popularity because of the following resins.
The plastics, prepared from phenolic resins, are only good in resisting weather effects. Certain plastics are seriously affected by ultraviolet light.
Plastics, being organic, are combustible. But the resistance to fire temperature depends upon the plastic structure.
Plastics generally possess sufficient durability, provided they offer sufficient surface hardness. Thermoplastic varieties are found to be attacked by termites and rodents.
Plastics easily maintain their shape and do not go under plastic deformations.
We hope you enjoyed the class.
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