The materials they are substances (natural or artificial) that are used to build other things. Each industry uses specific materials. For example, for the construction industry they are used as materials to metals, cements and ceramics, among others, while in the textile industry fabrics of cotton, wool and synthetics.
Each material distinguishes itself from others by its properties. Depending on the context in which you study a material or other materials with which you want to compare it, the properties that will be most relevant are different.
For example, if we want to know why oil forms a layer on the surface of water, we will be interested in two properties: solubility and density. Other properties such as toughness, color, odor or conduction of electricity will be less important.
The properties can be:
- Density. It is the amount of mass in a certain volume.
- Boiling point. It is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid. Above that temperature, the liquid turns into a gaseous state.
- Melting point. It is the maximum temperature at which a substance is in a solid state. Above that temperature, it becomes a liquid state.
- Solubility. It is the ability of a substance to dissolve in another.
- Electric conductivity. It is the ability of a material to conduct electricity.
- Flexibility. It is the ability of a material to deform without breaking. Its opposite is stiffness.
- Physical state. They are the solid state, the liquid state, the gaseous state and the plasma state.
- Organoleptic properties. They are color, smell, taste, texture, and temperature.
- Hardness. It is the resistance of a material to perforations, scratches and abrasion.
- Rigidity. It is the resistance offered by a material to bend or fracture when external forces are applied to it.
- Opacity. It is the ability to prevent the passage of light.
- Translucency. It is the ability of a material to let light through, but what can be seen through it is unrecognizable.
- Transparency. It is the ability of a material to let light through, and perfectly allow the vision of the object located behind it.
Examples of materials and their properties
- Oak wood. It is a hard and heavy wood, because its density is between 700 and 770 kg / m3. Due to its chemical characteristics, it is very resistant to rot. Due to its organoleptic conditions (specifically its aroma), it is used for wine barrels, since it transfers its characteristics to the final product.
- Glass. It is a hard material (very difficult to drill or mark), with a very high melting temperature (approximately 1723 ºC), so it is not affected by changes in temperature. That is why it can be used in various industries, from construction (windows) to tableware. Pigments can be added to glass that change its color (organoleptic properties) and other layers that make it opaque, preventing the passage of light. It is relatively insulating from noise, temperature, and has little electrical conductivity.
- Fiberglass. It is an artificial material produced from silicon dioxide filaments (SiO2). It is a good thermal insulator and is resistant to corrosion. It is also a good acoustic and electrical insulator. Due to its flexibility, it is used in tent structures, high resistance fabrics and poles for pole vaulting.
- Aluminum. In thin layers, it is a metal not only flexible but also soft, that is, it is extremely malleable. In thick layers and as part of certain alloys it becomes rigid. This is why aluminum can be used in flexible packaging (even so-called “aluminum foil”) but also in large rigid structures of all sizes, from food cans to airplanes.
- Cement. It is a mixture of calcined and ground limestone and clay. It hardens on contact with water. It is resistant to chemicals and high temperatures. However, its resistance decreases over time because its porosity increases.
- Gold. It is a soft and heavy metal. Due to its high resistance to corrosion, it is used in industry and electronics. It is known for its organoleptic characteristics (its brightness and color) for which it is even confused with other metals of lower economic value. It has a density of 19300 kg / m3. Its melting point is 1064 ºC.
- Cotton fiber. It is one of the materials used in the textile industry. Its color ranges from white to yellowish white. The diameter of the fiber is very small, between 15 and 25 micrometers, which makes it very soft to the touch, which is why it is highly appreciated in the industry.
- Lycra or elastane. It is a polyurethane fabric. It has great elasticity, it can be stretched up to five times its size without breaking. Plus, it quickly returns to its original shape. It does not retain water between the fibers of its fabrics, so it dries quickly.
- PET (polyethylene terephthalate). It is a thermoplastic of high rigidity, hardness and resistance. It is very resistant to chemical and atmospheric agents (heat, humidity), which is why it is used in beverage, juice and medicine containers.
- Porcelain. It is a ceramic material that is characterized by being compact and translucent, in which it differs from all other ceramics. It is rigid but fragile and of low elasticity. However, it is very resistant to chemicals and high temperatures.