Topics
Natural Resources – Air, Water and Land
- Natural Resources
- Atmosphere and Its Layers
- Air Around Us
- Composition and Components of Air
- Importance of Air
- Air Pollution and Its Causes
- Water: Our Lifeline
- Availability of Water
- Composition of Water
- Importance of Water
- Scarcity of Water
- Land
- Soil Formation
- The Importance of Conserving Earth’s Natural Resources
The Living World
Diversity in Living Things and Their Classification
Disaster Management
Substances in the Surroundings –Their States and Properties
Substances in Daily Use
Nutrition and Diet
- Nutrients and Nutrition
- Component of Food
- Carbohydrates
- Diseases Due to Deficiency of Carbohydrates
- Fats (Lipids)
- Diseases Due to Deficiency of Fats
- Proteins
- Diseases Due to Deficiency of Proteins
- Vitamin and Minerals
- Diseases Due to Deficiency of Vitamin
- Diseases Due to Deficiency of Minerals
- Fibre
- Diseases Due to Deficiency of Fibre
- Water
- Diseases Due to Deficiency of Water
- A Balanced Diet
- Nourishment and Malnutrition
- Food Adulteration
Our Skeletal System and the Skin
Motion and Types of Motion
Force and Types of Force
Work and Energy
- Force, displacement and work
- Energy
- The relationship between work and energy
- Forms of Energy
- Mechanical Energy
- Power Plants Based on Thermal Energy
- Light Energy
- Sound energy
- Chemical Energy
- Transformation of Energy
- Energy Resources
- Conventional energy resources or non-renewable energy resources
- Non-conventional energy resources or renewable energy resources
- Energy saving and green energy
Simple Machines
Sound
Light and the Formation of Shadows
Fun with Magnets
The Universe
- Introduction
- Vulcanisation of Rubber
- History of Vulcanisation
Introduction:
Rubber is a flexible material that can be stretched and used to make various everyday items. It comes in two types:
- Natural Rubber: It is obtained from the sap of rubber trees, known as latex. When collected, it appears sticky, white, and has a distinct smell.
- Artificial Rubber: It is also known as synthetic rubber and is man-made through chemical processes. It is produced from petroleum-based compounds such as styrene-butadiene or neoprene. Artificial rubber is designed to mimic the properties of natural rubber while offering greater resistance to heat, chemicals, and wear.
Vulcanisation of Rubber:
Vulcanisation is a special process used to make natural rubber stronger and more useful.
Steps in Vulcanisation:
- Mixing Sulphur: Rubber is mixed with a chemical called sulphur.
- Heating: The mixture is then heated for three to four hours.
Sulphur helps to harden the rubber. The amount of sulphur added depends on how hard the rubber needs to be for its use. For example: erasers, rubber toys, and rubber bands.
History of Vulcanisation:
A long time ago, a man named Charles Goodyear accidentally discovered the process of vulcanisation. He spilt a mixture of rubber and sulphur on a hot stove. When the fire went out, he noticed that the rubber had become much harder and less stretchy than before. He repeated his experiments more carefully and eventually created the vulcanisation process. This made it possible to make hard and durable rubber tyres, which greatly improved transportation.
