Bulk Properties Flashcards
(26 cards)
What types of interactions are found in a supramolecular assembly of a polymer?
Hydrogen bonds, van der Waals forces, ionic interactions, hydrophobic interactions, and π–π stacking.
These interactions contribute to the stability and functionality of polymer assemblies.
What types of interactions are found in a supramolecular assembly of a metal?
Metallic bonding — a lattice of positive ions in a sea of delocalized electrons.
This structure allows metals to conduct electricity and heat efficiently.
What types of interactions are found in a supramolecular assembly of a metal alloy?
Metallic bonding with possible strain fields from substitutional or interstitial atoms; may include ionic/covalent bonding in surface oxides.
The presence of different atoms can alter the properties of the alloy.
Order the following interactions by strength (weakest to strongest): van der Waals, H-bond, ionic, covalent, metallic.
van der Waals < hydrogen bond < ionic bond < metallic bond < covalent bond.
This order reflects the typical energy associated with each type of bond.
How do you interpret a tensile test result?
Analyze the stress-strain curve to identify elastic region, yield point, plastic deformation, ultimate tensile strength, necking, and fracture point.
Each of these points provides critical information about material behavior under stress.
What is the equation to calculate Young’s modulus from a stress-strain curve?
E = stress / strain = (σ/ε) = (F/A) / (ΔL/L₀)
Young’s modulus is a measure of the stiffness of a solid material.
Can you calculate Young’s modulus from a gf/mm value if given area and displacement?
Yes, convert gf/mm to N/mm, then apply E = (F/ΔL) × (L₀/A).
Accurate unit conversion is essential for correct calculations.
Why is the first step in calculating Young’s modulus converting gf/mm to N/mm?
Because Young’s modulus requires SI units (N and mm) to properly calculate stress and strain.
Consistency in units is critical for accurate engineering calculations.
How can you identify ductile, brittle, and soft materials from a stress-strain curve?
Ductile materials show long plastic regions, brittle materials break with little strain, soft materials have low modulus and strain easily.
The shape of the stress-strain curve provides insights into material properties.
What is the difference between axial and shear loads?
Axial loads act parallel to the axis (tension/compression); shear loads act parallel to the surface, causing layers to slide.
Understanding these loads is crucial in structural engineering.
Which is brittle: bone or tendon?
Bone is brittle.
Bone’s structure contributes to its brittleness compared to tendon.
Which is ductile: bone or tendon?
Tendon is ductile.
Tendons can stretch and deform without breaking, unlike bone.
How can brittleness vs ductility be determined biomechanically?
By analyzing stress-strain curves; brittle materials fail at low strain, ductile materials deform plastically before failure.
This analysis is essential for material selection in biomedical applications.
What is elastic deformation?
Temporary deformation that is fully reversible upon removal of the load.
Elastic deformation occurs within the material’s elastic limit.
What is plastic deformation?
Permanent deformation that occurs after a material surpasses its yield point.
This type of deformation is critical in manufacturing processes.
What is yield strength?
The stress at which a material transitions from elastic to plastic deformation.
Yield strength is a key parameter in material design.
What is ultimate strength?
The maximum stress a material can withstand before necking begins.
This property is essential for assessing material performance under load.
What is necking?
Localized thinning of a material after ultimate strength is reached.
Necking indicates the onset of failure in ductile materials.
What is fracture strength?
The stress at which the material finally breaks.
Fracture strength is critical for understanding failure mechanisms.
What is fracture?
Complete failure and separation of the material under stress.
Fracture analysis helps in failure prevention strategies.
What is the difference between a surface property and a bulk property?
Surface properties relate to the outermost layer and affect interactions (e.g., wettability), while bulk properties relate to the whole material (e.g., strength, stiffness).
This distinction is important in material science and engineering.
What is surface erosion of a biomaterial?
Degradation that occurs only at the outer surface, layer by layer.
Surface erosion can affect the performance of biomaterials in medical applications.
What is bulk erosion of a biomaterial?
Degradation that occurs throughout the entire volume of the material.
Bulk erosion is often associated with hydrophilic materials.
Which biomaterials tend to undergo surface erosion?
Hydrophobic polymers like polyanhydrides and poly(ortho esters).
These materials degrade more slowly, affecting their applications.
