POLYMER STRUCTURED

Polymer Structured

Polymer Structured

Answer no. 2

Thermoplastic is also called thermo softening plastic. It is a kind of polymer that becomes moldable or pliable after reaching at particular temperature. It expands above particular temperature and gets back its original shape after getting cool. It is often observed that most thermoplastics have large molecular weight. The molecules of such polymers are attached with each other by intermolecular forces. These intermolecular forces allow the thermoplastics to retain their shapes after getting cool. This phenomena differs the thermoplastics from thermo setting polymers in which the chemical bonds break down upon melting and don't retain its original shape after getting cool. Thermoplastic materials can be characterized in to two types of molecular arrangements, semi-crystalline thermoplastics and amorphous thermoplastics (Potsch &Michaeli, 2008, pp. 111-113). The properties of semi-crystalline thermoplastics and amorphous thermoplastics are quite different from each other which are discussed in the proceeding.

Thermoplastics can be categorized in to two types of classes (semi-crystalline and amorphous). Their categories are determined by both their structure in different states and their transition temperature. Although, amorphous polymers do not have a sharp transition between solid and liquid states. Instead of this, an amorphous thermoplastic polymer liquefies itself as the temperature of the material lowers than Tg, glass transition temperature. It should be noticed that the amorphous thermoplastics can be utilized lower than their glass transition temperature. The maximum temperature at which amorphous thermoplastics can be processed is approx hundred degrees centigrade above glass transition temperature. It is the characteristic of amorphous thermoplastics that it does not alter its structure after getting in to solid state. Due to its characteristic features these types of thermoplastics are usually transparent (Schwarzmann, 2001, pp. 200-202).

It is a great characteristic of amorphous thermoplastic that, in its solid state it is found in brittle state. The stiffness of amorphous thermoplastic, decreases, with increase in its temperature. This increase in temperature causes it to become rubbery or leathery. After exceeding the glass transition temperature, the strength of these thermoplastics decreases considerably with the continuous increase in strain. Once it turns in viscous state, the mechanical strength of these thermoplastics becomes negligible.

All types of thermoplastics provides several advantages over conventional materials, for example, low manufacturing energy, ability to design complicated shapes comparatively easily, having low density and lower costs. The typical properties of an amorphous thermoplastic in comparison to a semi-crystalline thermoplastic are briefly discussed in the ...