BE 450 PPT 7 Physical Properties - Exam 2

physical

what kind of properties are the following? mechanical, hydrophobicity, crystallinity, porosity, surface area, surface topography

chemical

what kind of properties are the following? amine groups, carboxyl groups, surface charge, elemental makeup, degradability

biocompatibility

what kind of properties are the following? toxicity, protein adsorption, hemo-compatibility, cellular response, animal studies

mechanical testing

systematic process used in engineering and material science to evaluate the physical and mechanical properties of materials, components, or products when subjected to various external forces, stresses and environmental conditions

mechanical testing

informs design decisions, ensures safety and reliability, critical in the development of new materials

tensile, compressive, shear

types of mechanical testing: elastic modulus, strain, ductility, toughness, ultimate strength etc.

torsional

types of mechanical testing: rotational force

cyclic

types of mechanical testing: repeated tensile or compressive forces

biaxial

types of mechanical testing: loading in 2 directions simultaneously

3 or 4 point bending

types of mechanical testing: both compressive and tension forces

rheological

types of mechanical testing: viscosity measurement

wear

types of mechanical testing: resistance to repeated mechanical forces

stress

mechanical testing basics: load applied to a certain cross-sectional area of an object

tensile

type of stress?

compressive

type of stress?

shear

type of stress?

torsional

type of stress?

biaxial

type of stress?

bending

type of stress?

strain

mechanical testing basics: extent of deformation relative to its initial condition

normal strain

the ratio of the change in length to the original length

normal strain

equation for what?

shear strain

equation for what?

dimensionless

unit for normal stress

radians

unit for shear stress

positive

tensile strain is positive or negative?

negative

compressive strain is positive or negative?

stress

apply normal force

-> use area of subject

-> __________

strain

measure deformation

-> based on length change

-> _________

instron

typical mechanical testing device

Instron: interchangeable ______ cells

linear

Instron: very accurate _________ motion

fixtures

Instron: variety of clamps or _________ for many tests

fiducial

biaxial mechanical testing requires __________ markers

tissue

biaxial mechanical testing tracks movement of _________ under load

hooks

biaxial mechanical testing has ________ to immobilize sample

temperature

biaxial mechanical testing may require _______________ control and/or water bath

hydrophobicity

the property of being water-repellent

surface hydrophobicity

__________ _________________ is a crucial regulator of: cell adhesion, protein adsorption, drug delivery, surface degradation

contact angle

interfacial tension present between a solid, a liquid, and a vapor

contact angle

the ___________ __________ is the angle between the tangent line and the solid surface

more

________ hydrophobic -> greater angle

hydrophobic

hydrophobic or hydrophilic?

hydrophilic

hydrophobic or hydrophilic?

goniometer

hydrophobicity is measured by a contact angle ______________

mechanical, thermal, chemical

degree of crystallinity and the organization of the crystalline regions influence what 3 properties?

crystallinity

DSC - differential scanning calorimetry (degree of ______________)

Diffraction

XRD - X-Ray _____________ (organization of crystalline region)

order

DSC: crystals give ________ to a substance

heat

______ disrupts order (cause thermal transitions)

DSC

thermo-metric methods such as ______ can measure degree of crystallinity

amorphous

blue

semicrystalline

red

rubbery

at Tg, the sample becomes more __________

freely

polymer chains move around more _________

heat

at Tc crystal forms and releases ______

melted

at Tm crystal is ___________

energy/mass

Area under the curve is _______/______

melting

(deltaHm^o) - reference of ___________ for 100% crystalline material

atoms

XRD - examine show X-rays are diffracted from _______ in a material

structures

XRD - commonly used to determine ____________ of crystals (miller indices and cell size)

wavelength

X-ray _____________: 0.5-50 angstroms, similar to distance between atoms in a solid

diffraction

_____________ occurs when incident rays are scattered by atoms in a way to reinforce the wave

constructive, destructive

two types of diffraction that occurs during XRD

directions

XRD single particle: incident beams scattered uniformly in all ____________

constructively

XRD solid: scattered beams interfere _________________ in some directions, producing diffracted beams

pattern

XRD solid: random arrangements cause beams to randomly interfere, and no distinctive __________ is produced

regular

XRD crystalline material: regular pattern of crystalline atoms produces __________ diffraction pattern

crystal

XRD crystalline material: diffraction pattern gives information on ___________ structure

constructive

what type of interference?

destructive

what type of interference?

bragg's law

equation name?

d

lattice interplanar spacing of the crystal

theta

x-ray incidence angle (bragg angle)

lambda

wavelength of the characteristic x-rays

surface topography

affects host/implant interactions,

surface topography

can affect biocompatibility

surface topography

can influence functionalization

surface probe microscopy

surface topography: SPM meaning

scanning tunneling microscopy

surface topography: STM meaning

atomic force microscopy

surface topography: AFM meaning

scanning electron microcopy

surface topography: SEM meaning

weak

STM: based on quantum mechanics - _______ electric current between tip and sample

voltage

STM: current created by ___________ potential between sample and tip

heigh, current

STM: scanning maintains constant _______ or constant __________ to determine topography

attractive, repulsive

AFM: operates through _____________ and _____________ forces between tip and samples

laser

AFM: based on a _______ feedback system

resolution

AFM: tip size and shape, as well as scan speed determines _____________

ligand

AFM in biological application: coat tip with __________

binding

AFM in biological applications: interrogate surface to look for ___________ events

protein, antibody

AFM in biological applications: __________ interactions, _____________ binding events

integrins

AFM in biological applications: ligand binding to ____________ (force measurements of biochemical processes)

F

AFM for micromechanical testing: force

k

AFM for micromechanical testing: spring constant

D

AFM for micromechanical testing: distance

repulsive

AFM for micromechanical testing: red

attractive

AFM for micromechanical testing: blue

electrons

SEM: anode draws in ___________

specimen

SEM: magnetic lens as a condenser to focus the electrons through the detector onto the ______________

scan

SEM: stage moves to raster over _____ region