Polymer and Ceramic Materials: Properties and Applications
To obtain a polymer in polymer chemistry, hundreds of thousands of monomer molecules are chemically bonded. This creates homopolymers. If the polymer chain is formed by the union of different monomers, copolymers are obtained. In polycondensation, chain growth occurs by chemical reaction between two functional groups, most often with the loss of a small molecule, such as water or hydrochloric acid. In polyaddition, chain growth occurs by continuous addition of the same type of small molecules that bind to each other without causing the loss of any molecule.
Oil: A dark liquid less dense than water. It is a mixture of hydrocarbons composed of hydrogen and carbon. Contains paraffin, naphthalene, and aromatics.
Polymer Types
Thermoplastic Polymers
These polymers form long, rigid chains of carbon atoms. Plastics are made in this way and can be shaped by heating and subsequent solidification in a mold. Common examples include polyethylene, polystyrene, and methacrylate.
Thermosetting Polymers
These polymers are more resilient but also more fragile, forming cross-linked carbon atom chains. They do not support recycling, as they decompose when heated. Examples include phenolic resins used in adhesives, polyurea, and certain elastomers.
Elastomers
These polymers, like rubber, can deform under pressure and return to their initial state when the pressure is removed. Examples include silicone, polybutadiene, and polychloroprene.
PET (Polyethylene Terephthalate): A polyester used in the manufacture of fibers, bottles, films, and various parts.
Ceramic Materials
Ceramic materials are compounds composed of metallic and non-metallic elements bound by ionic and/or covalent bonds. They perform better than metals and polymers at high temperatures and in aggressive environmental conditions. However, their fragility limits their use in some industrial applications.
Types of Ceramics
- Glass: Contains 70% silicon, plus soda and lime. It is a non-crystalline ceramic.
- Crystalline Ceramics: These materials lose their crystalline state through controlled solidification procedures, reaching a polycrystalline state. Examples include heat exchangers and cooking hotplates.
- Clays: Hydrated alumina silicates that are easily molded. Their products are classified into whiteware and structural clay products.
- Refractories: Composed of coarse particles, often metal oxides, bound together by finer refractory materials. They resist chemical attack and high temperatures.
- Abrasives: Examples include diamond, silicon carbide, tungsten carbide, and alumina.
- Cements: Calcium silicates in powder form that, when mixed with water, form a paste that hardens at room temperature.
Ceramics: Ceramic materials are impact-resistant, but their processing is slow and expensive. They have higher mechanical resistance than other ceramic materials.
Advanced Ceramics: This group includes carbides, nitrides, oxides, and borides. They have excellent mechanical and physical properties at high temperatures. Examples:
- Aluminum Nitride: Good resistance to high temperatures and an excellent thermal conductor. Used as insulating plugs and in orthopedic implants.
- Alumina Nitride: A good electrical insulator with high thermal conductivity. Used in integrated circuits.
- Silicon Carbide: Excellent corrosion resistance at high temperatures. Used as a coating for metals and in manufacturing.
- Boron Carbide: A hard, lightweight material extremely resistant to abrasion.
- Alumina and Aluminum Oxide: Pure aluminum metal is ductile and malleable, able to withstand impacts. Aluminum oxide is a chemically stable ceramic material with a melting point of 2020°C, resistant to high temperatures but very fragile.
Cermet: A composite material consisting of ceramic particles in a metallic matrix.
Composite Materials
Composite materials are formed by a matrix or binder material and other materials in the form of fibers or particles as reinforcement. The resulting material combines the best properties of each component.
Types of Reinforcement
- Particle Reinforcement: The particles are harder than the matrix and improve the mechanical properties of the composite material. Cermets are made with hard particles like WC and TiC in a metallic matrix of nickel or cobalt.
- Fiber Reinforcement: Fibers enclosed in a soft and ductile matrix.
- Structural Reinforcement: Classified into laminar and sandwich structures. Laminates are composed of stacked plates with different reinforcements in different directions, such as plywood. Used in the manufacture of aircraft fuselages and building walls.
There are several types of matrices.