Thermoplastics are the biggest constituent material group in polymer materials. This is because the mechanical properties of thermoplastics are preferrable around other polymer types. Because of these mechanical properties, thermplastic polymers find lots of applications areas in engineering. In here, we explain the general properties thermoplastic polymers.
Actuallyi thermoplastic materials have lower mechanical properties generally; lower stiffness, hardness and greater ductility compared with ceramics and metals. These mechanical properties of thermoplastics depend on temperature.
As you know that thermoplastics can have crystalline or amorphous molecular forms. So mechanical properties of a thermoplastic material changes according to its molecular form. If we consider the amorphous thermoplastics, they have a very critical property called as ‘glass-transition temperature(Tg)’. Below the glass transition temperature, amorphous thermoplastics show solid characteristics. If amorphous thermoplastics are heated up around Tg, they will start to show rubbery characteristics. This rubbery characteristics of thermoplastics called as viscoelasticity. At melting temperature of these thermoplastic materials, they show completely liquid characteristics called as viscous state.
But for crystalline thermoplastics, they do not have any Tg that they show rubbery characteristics. Crystalline thermoplastics are completely solid up to their melting temperature. After melting temperature, crystalline thermoplastics become completely liquid abruptly.
But there is a degree of cristallinity for mosy thermoplastic materials. So they can have both crystalline molecular structures and amorphous structures. So, these kinds of thermoplastics show mechanical and physical characteristics between complete cristalline and complete amprphous thermoplastic materials.
Also degree of polymerization and molecular weight of thermoplastics are very important parameters for properties. If the degree of polymerization and molecular weigth increases for thermoplastics, they become more strong and hard mechanically. But their flowability reduced. This makes hard to process these high DP and MW of thermplastics.
Mechanical properties of thermoplastics according to their different characteristics can be summarized as above. Do not forget to leave your comments and questions about properties of thermoplastics below. You percious feedbacks are very important for us.