Thermoplastic materials

Two main categories of Thermoplastic materials are amorphous and Crystaline. While some materials classified in other categories and some of the material is a combination of both. Polymers like Polymethylmethacrylate, Polycarbonate and Polystyrene is an amorphous polymer chains, ie with a random molecular chain structure and become actively engaged in a wide temperature range. This means that the material is not called liquid but more accurate to say softened. And this material begins to soften so heating is carried out. Increasingly soft as the heat absorbed, until finally absorbing a lot of heat and eventually called the "melting".




Amorphous polymers do not have a specific melting point. At low temperatures they are hard, dense, brittle and luster, at high temperatures such as rubber or leather. Temperature when the transition occurs is called the Glass-Transition Temperature (Tg), also called Point glass or glass temperature.

In Crystaline material, regular molecular chain structure and become active only after the material is heated to its melting point. This means that these materials do not pass through a phase softened, but remained solid until heated at certain temperature and instantly melted material.



Differences property amorphous and Crystaline


Amorphous

* Net

* Low Shrinkage

* Softened

* The high mashed

* Lack of chemical resistant


Crystaline

* Opaque

* Depreciation high

* Melt

* Low Power mashed

* Hold chemicals



Examples of materials based on molecular structure


Amorphous

* ABS

* Acrylic

* Polyamide

* Polyacrylate

* Polycarbonate

* Polystyrene

* Polyurethane


Crystaline

* Acetal

* Nylon

* Polyester (PBT)

* Polyethylene

* Polyethyleneterephthalate (PET)

* Polypropylene

* Polyvinylcloride (PVC)



To improve the ductile properties of amorphous glass below its transition temperature we can mix it with some elastomers. This is known as an elastomer polymers dimodofikasi into rubber. Some examples of the elastomer is Acrylates, Butyls, Fluorosilicon, Fuorocarbons Polysulfids polyurethane.

The ability of plastics to return to his native structure after heating and then softened or melted in other words, reversible process called Thermoplastic. If we raise the temperature above the Tg of his skin then first became such as rubber along with the addition of temperature. finally at a temperature above its melting point at Crystaline become viscous fluid with a viscosity decreases with further increase in temperature. In the liquid phase resembles a plastic ice cream can be formed. Because of its recyclable plastic can then be formed up to several times, but repetition of heating and cooling causes the reduction in the quality of the plastic.

When Thermoplastic deformed or are interested, this process is called orientation. Like the metal polymer becomes anisotropic. Specimens become more powerful and solid in the direction of pull than the transverse direction. Another important thing is the ability of water-absorbing polymer. Water makes the plastic becomes more plastic. With the addition of moisture, Glasstransition Temperature, voltage and modulus of elasticity will be lower. Dimensional changes also occur due to moisture environment.


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