Thermoplastics Explained
Thermoplastics and thermosets constitute the two main types of plastics. Unlike thermosets, thermoplastics can be melted and reformed into new plastic. After a thermoplastic cools and solidifies, it holds its shape during use. All plastics are synthetic, or man-made, chains of molecules called polymers, such as polyethylene and polypropylene. Different polymers combine in different ways to give plastics distinct properties.
Other People Are Reading
-
Structure
-
Thermoplastics are organic because they contain largely carbon monomers. A monomer is a molecule that usually contains carbon and hydrogen and may contain other elements, like oxygen and nitrogen. Multiple monomers chain together to become a polymer. A simple polymer chain can be "A" and "B," organized in an "A-B-A-B-" pattern. However, complex chains can be organized differently or contain more letters.
-
Properties
-
Thermoplastics have a wide range of properties. They can be soft and ductile, like rubber, or hard and durable, like metal. Some thermoplastics are heat-resistant at 600 degrees Fahrenheit, while others are cold-resistant at -100 degrees Fahrenheit. Depending on what elements are used in their processing, thermoplastics can be used as insulators to protect against heat and electricity, or can even conduct electricity.
Advantages
-
Thermoplastics can be molded into any shape, are generally lightweight and cost little to make. They can replace metals when weight is an issue and can be crafted with a high degree of precision. They can also withstand more stress than metal without deforming, meaning metal would bend before plastic would. Thermoplastics are used in computer, medical, automobile and many other manufacturing industries.
Disadvantages
-
The biggest disadvantage to thermoplastics is that they can melt when they're heated. They can also suffer damage from sunlight. And unlike metals, they're susceptible to deformation after long-term stress. Thermoplastics also tend to break rather than deform under excessive stress.
Manufacturing
-
Thermoplastics are manufactured principally by injection molding, thermoforming, and extrusion molding. With injection molding, melted plastic is forced into a cold mold under high pressure. Thermoforming heats plastic films to soften them, then pushes them into a mold by a vacuum or plug. Extrusion molding forces the melted plastic through a die, which creates the shape of the plastic. Pipe, film, and electrical wire insulation are examples of plastic products molded by extrusion.
Recycling
-
Thermoplastics are recyclable resin compounds that can be reused and reformed after reprocessing. The recycling of thermoplastic can reduce trash, cut processing costs, and can help save the environment since plastics are not biodegradable. After reprocessing, the recycled plastic is reground into pellets which are melted and used for injection or extrusion molding.
References
Resources
- Photo Credit "LEGOS workers fired from their jobs" is Copyrighted by Flickr user: woodleywonderworks (woodley wonderworks) under the Creative Commons Attribution license.
