Thermoplastics properties , types , uses , advantages and disadvantages
Thermoplastics can be differentiated from the thermoset materials , They are the organic materials that melt when they are heated , They can be remelted back into the liquid , They are formed when they are in the melted or viscous phase , They are heated , formed & cooled in their final shape , whereas the thermoset plastics remain in the permanent solid state .
Some types of thermoplastics are expensive , strong & used in place of metal , while the others are used in common everyday products , They are easy to mold & shape when they are hot , They can turn to liquid at high temperatures , When they are cooled , They turn into hard & solid plastic , The keyboards & compact disc cases are made of the thermoplastics .
The most popular methods of processing thermoplastics are injection molding , extrusion , and thermoforming , The thermoplastics can be like rubber or as strong as aluminum depending on their chemistry , They are light weight , with densities of 0.9 to 2 gm/cc , Some thermoplastic materials can withstand the temperature extremes up to 600 F , while the others retain their properties at -100 F .
Some thermoplastic materials have no known solvents at room temperature , The thermoplastic composites can be made to be electrically conductive with the addition of carbon or metal fibers , The combination of light weight , high strength & low processing costs make the thermoplastics well suited to many applications , They are used as thermal insulators & electrical insulators .
Two types of thermoplastics are high-temperature thermoplastics and engineering thermoplastics , Examples of high-temperature thermoplastics contain popular materials such as polypropylene and PVC , They are commonly used for the pipes , the bottles and the plastic containers .
Engineering thermoplastics are typically flame-retardant & they can withstand the temperatures of up to 100 degrees C , Engineering plastics cost much more to produce than these popular materials , They contain the materials such as the nylons and the polyesters .
One type of the thermoplastic which is called polyester resin , It is used for the car bodies and the garden furniture , Another type of thermoplastics is polymethyl methacrylate , It is used for the lenses and the windows .
Thermoplastics are energy efficient both in their manufacture & processing , Thermoplastic components can be made in very high volume with high precision & low cost , They can replace the metals with a considerable weight savings , proper care is taken in design , Most thermoplastics have better fatigue properties than the metals and they can tolerate larger deflections than the metals without deforming .
The thermoplastics can be remolded & recycled without negatively affecting the material’s physical properties , They can soften when they heated & they become more fluid as additional heat is applied , The curing process is completely reversible because no chemical bonding takes place .
Thermoplastic materials resin & they offer many performance benefits , but most thermoplastic materials offer high strength , shrink-resistance & easy bendability , Depending on the resin , They are used in the low-stress applications such as the plastic bags or high-stress mechanical parts .
Thermoplastics materials have high strength , They are lightweight & they comes with relatively low processing costs , You can manufacture the thermoplastic components easily in high volumes with high precision , The engineers use the thermoplastics instead of the metals because of their much lighter weight .
Thermoplastics materials are highly recyclable , They offer aesthetically-superior finishes , They have High-impact resistance , They contain remolding / reshaping capabilities , They offer a chemical resistant , They have hard crystalline or rubbery surface options and they have Eco-friendly manufacturing .
The thermoplastics can soften or melt when they heated and returning to solid when they cooled , The process is repeatable and it does not change the chemical nature of the polymer , Heating provides the thermal energy to allow the long polymer chains to move freely past one another and take on new shapes , Cooling reduces molecular motion to the level where the chains no longer move freely .
The thermoplastics , with the exception of polyester and polyimide film , have only recently gained popularity , particularly for microelectronic structures in the recent times , Advanced thermoplastics can now provide high melting points and exceptional stability early generation polymers could not offer .
Many thermoplastic materials , especially the composites , tend to fracture rather than deform under high stress levels , They suffer from creep where the thermoplastics materials relax or weaken when they exposed to long-term loading .
The primary drawback of using the thermoplastics instead of the materials such as the metal is that the thermoplastics can melt , Some types of low-quality thermoplastics melt , some thermoplastics degrade when they’re exposed to direct sunlight or ultraviolet light levels for the extended times .
Thermoplastics are more expensive than thermoset materials and they can melt if they heated , Many materials have poor resistance to hydrocarbons , organic solvents and highly polar solvents but the others have excellent resistance to these materials .