Lecture 04: Mechanical and Thermophysical Properties of Polymers

Vocabulary flashcards for key concepts from the lecture.

Crystalline Solids

Materials where atoms or molecules are arranged in a highly ordered and repeating three-dimensional pattern.

Amorphous Solids

Materials lacking a well-defined, repeating crystal structure; atomic arrangement is more random.

Semi-Crystalline Solids

Materials exhibiting a combination of crystalline and amorphous structures; ordered crystallites dispersed within an amorphous matrix.

Polymer Crystallinity

A condition that exists when molecular chains are aligned and packed in an ordered atomic arrangement.

Tensile Strength (TS)

The maximum stress that a material can withstand while being stretched or pulled before failing or breaking.

Yield Strength (σy)

The amount of stress a material can withstand before undergoing permanent deformation.

Brittle Response

Characterized by fracture with little or no plastic deformation (aligned, crosslinked, and networked polymers).

Plastic Response

Characterized by significant plastic deformation before fracture (semi-crystalline polymers).

Melting Temperature (Tm)

The temperature at which a polymer crystal transforms from a solid with ordered structure to a viscous liquid with random structure.

Glass Transition Temperature (Tg)

The temperature at which an amorphous or semicrystalline polymer transitions from a rigid state to a rubbery state upon heating, or vice versa upon cooling.

Rheology

The study of deformation and flow of materials.

Viscosity

A property of a fluid that represents the resistance to flow when subjected to an applied force.

Shear Stress (τ)

Force per unit area applied parallel to a surface (τ = F/A).

Shear Strain (γ)

The 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.