Lecture 9 (BME 296)

Elasticity

The ability of a material to return to its original shape after being stretched or compressed.

Plasticity

The ability of a material to undergo permanent deformation when a sufficient load is applied.

Semicrystalline Polymers

Polymers that contain both crystalline and amorphous regions, structured in lamellae and interspersed by amorphous tie molecules.

Strain

The deformation of a material in response to an applied stress.

Creep

Time-dependent plastic deformation of a material under constant load.

Necking

The narrowing of a material in a specific location due to applied tensile stress, leading to eventual fracture.

Crystallinity

The degree of structural order in a polymer; higher crystallinity typically increases a polymer's mechanical strength.

Molecular Weight

The weight of a molecule, which influences the physical properties of polymers, including strength and flexibility.

Cross-linking

The process of chemically joining two or more polymer chains, which can enhance a polymer's strength and rigidity.

Flexural Strength

The ability of a material to withstand deformation under load, often calculated from the modulus of rupture in bending tests.

Fatigue

Progressive and localized structural damage occurring when a material is subjected to cyclic loading.

Tensile Modulus

Also known as Young's Modulus, it measures a material's ability to withstand changes in length when under lengthwise tension or compression.

Modulus of Rupture

The stress at which a material fails in bending.

Amorphous Regions

Non-crystalline areas within a polymer that provide flexibility and toughness.

Primary Bond Interactions

Strong interactions between atoms within a polymer that contribute to its overall strength.