Lecture 04: Mechanical and Thermo-physical Properties of Polymers

Vocabulary flashcards based on the lecture notes covering crystalline and amorphous solids, polymer properties, crystallinity, mechanical properties, melting and glass transition, and rheology.

Crystalline Solid

Solid material where atoms or molecules are arranged in a highly ordered and repeating three-dimensional pattern called a crystal lattice.

Amorphous Solid

Solid material lacking a well-defined, repeating crystal structure; the arrangement of atoms or molecules is more random.

Semi-Crystalline Solid

Solid material exhibiting a combination of crystalline and amorphous structures, with ordered crystalline regions (crystallites) dispersed within an amorphous matrix.

Polymer Crystallinity

Condition where molecular chains are aligned and packed in an ordered atomic arrangement.

Tensile Strength (TS)

Maximum stress that a material can withstand while being stretched or pulled before breaking.

Yield Strength (σy)

The amount of stress a material can withstand before it begins to deform permanently.

Melting Temperature (Tm) of Polymers

The temperature at which a polymer transitions from a solid with ordered structure to a viscous liquid with random structure over a range of temperatures.

Glass Transition Temperature (Tg) of Polymers

The temperature at which an amorphous or semicrystalline polymer transitions from a rigid state to a rubbery state upon heating, or from a liquid to a rubbery material and finally to a rigid solid upon cooling.

Rheology

The study of deformation and flow of materials.

Viscosity

A property of a fluid that resists the force causing it to flow. Viscosity represents the resistance to flow.

Shear Stress (τ)

Force per unit area applied parallel to a surface; measured in Pascal (Pa).

Shear Strain (γ)

Deformation of a material caused by shear stress.

Viscoelasticity

The property of materials that exhibit both viscous and elastic characteristics when undergoing deformation.

Rheometry

Experimental techniques and tools used to determine the rheological properties of materials.

Rheometer

A laboratory device used to measure the way in which a liquid, suspension, or slurry flows in response to applied forces.