characteristic and propites of plastic
Answers
Answer:
Properties of Plastic. Plastics are generally low cost, easy to manufacture, durable, strong for their weight, electrically and thermally insulative, and resistant to shock, corrosion, chemicals, and water.
Answer:
The Properties of Plastic
Plastic is a synthetic material created from a broad range of organic polymers that have become an indispensable part of our everyday world. The properties of plastic are numerous. For the most part, they are
Lightweight with a high strength-to-weight ratio
Can be manufactured inexpensively and mass produced
Water resistant
Shock resistant
Thermally and electrically insulating
CHEMICAL PROPERTIES OF PLASTIC
There are two primary forms of plastic: thermoplastic and thermoset plastics, the use of which is dependent on the application. The main physical difference between the two is that one can be reused time and again, and the other cannot. When thermoplastics are heated, there is no chemical bonding and the material’s physical properties remain unaffected. Thermoplastics then, can be molded, melted, and remolded repeatedly into various shapes, sizes, and objects.
Thermoset plastics are polymers similar to, but generally stronger than, thermoplastics because of the polymer’s molecular cross-linking. They are so named because the polymers experience a chemical change during processing to form an irreversible chemical bond when mixed and molded. Once formed and solidified, i.e., a process known as curing, the plastic becomes “set.” The transformation process from a liquid state to a solid state is irreversible and provides an ultra-strong end product. It cannot be melted or remolded and is resistant to solvents.
Thermoset molding compounds are designed for processes such as Resin Transfer Molding (RTM) and Reaction Injection Molding (RIM) with pDCPD (Polydicyclopentadiene), one of the more impact-resistant plastics available.
Property of Plastics
Plastic properties are classified by 5 criteria.
The properties mentioned here could be references for plastic selection. However, these properties are subject to change due to temperature or humidity changes. Therefore, it is necessary to account for changes in environmental conditions on selection of plastics.
Mechanical properties
Mechanical properties refer to displacement or breakage of plastic due to some mechanical change such as applying some load.
Mechanical properties are dependent on the temperature, force (load), and the duration of time the load is applied. It may also be affected by ultra-violet radiation when used outside.
Thermal properties
Thermal properties include heat resistance or combustibility.
Thermoplastic has a larger coefficient of thermal expansion or combustibility and a smaller thermal conductivity or specific heat than other material such as metals.
Chemical properties
Chemical resistance, environmental stress crack resistance , or resistance to environmental change are referred as chemical properties.
When a plastic contacts chemicals, there is some kind of change. After having a plastic in contacted with chemicals under no stress for about a week, changes in appearance, weight and size of the plastic are examined. Such changes are referred to as chemical properties.
Electric properties
Electric properties are also referred to as electromagnetic properties. Electric properties include insulation, conductivity and electro-static charges.
Due to their good insulation property, plastics are often used in electric fields. However, plastics do have a defect; they are easily electrified.
Physical properties
Specific gravity, index of refraction and moisture absorption are called physical properties.
The specific gravity of the plastic is small, and it varies depending on the character of high polymer , or thermal and mechanical treatment of the plastic.