Characterization Study Guide

Question 1

State and describe a technique to measure thermal properties of polymers.

Answer 1

Differential Scanning Calorimetry-

the polymer is heated and as this happens the enthalpy changes… more current is required to then keep reference temperature constant. the power difference between the sample and reference is plotted against temperature.

Question 2

state three advantages of SIMS and XPS for surface analysis

Answer 2

• high sensitivity
• more sensitive to top surface
• applicable to any solid

Question 3

what principle is thermogravimetry analysis?

Answer 3

based on the monitoring and recording of changes in weight of a sample as it under goes controlled thermal degration. with varying temperature or time

Question 4

what is gel permeation chromatography

Answer 4

• an extremely powerful method for determining molecular weight distribution of a polymer…
• that separates analytes on the basis of size… polymer molecules elute from the chromatography in order of decreasing molecular size

Question 5

what is contact angle measurement?

Answer 5

• the a angle that is between the surface and a line that is tangent to a drop of liquid on the surface at the point where it intersects the surface.

if it is less than 90 degrees hydrophillic.

more than 90 degrees hydrophobic

method may tell us details about lubericity- hydrophilicty, and hydrophobicity

Question 6

What are advantages and disadvantages to an invivo experiment?

Answer 6

Advantages- —-.better approximation to human environment
-A step often required to proceed on to clinical use.

disadvantages
-costly
-may take longer to test
-harder to control
-demanding protocols (Animal Welfare Act)
-

Question 7

what is atomic force microscopy?

Answer 7

• its a imaging method that exploits intermolecular interactions between small probe and molecules on surface
• gives good indication of surface topography/features
• through use of prob it graphs the “contact mode, intermitant contact mode, and non contact mode

Question 8

when a contact angle is below 90 degrees, is it hydrophobic or hydrophillic

Answer 8

less than 90= hydrophillic

Question 9

what does in-vitro and in vivo mean?

Answer 9

vitro- experiments done outside of body… example cell cultures in glass

vivo- experiment conducted inside a living organism… example animal experiments

Question 10

name two techniques that could be used for structural analysis of polymers

Answer 10

raman spectroscopy

NMR (nuclear Magnetic Resonance Spectroscopy)

FTIR (Fourier Transform Infrared Spectroscopy (IR))

Question 11

Name two techniques for surface analysis and describe the information obtained by each in this technique.

Answer 11

• contact angle measurments- may provide details about lubericity-hydrophillicty and hydrophobicity
• ellipsometer- may provide information of the thickness of coatings of a material

Question 12

state two techniques for image analysis and describe the information obtained by each of this technique

Answer 12

-optical microscopy- a image is provided from a light source that is reflected/transmitted, magnification is the smallest, low resolution and depth of field. however it is the cheapest.

-SEM/EDX- scanning electron microscopy with energy dispersive x-Ray detector
- has high resolution and high depth of field. Electrons are bombarded then
reflected to portray image.

Question 13

What is GPC and what information does this technique provide

Answer 13

Gel permeation chromotography

• an extremely powerful method for determining molecular weight distribution of a polymer…
• that separates analytes on the basis of size… polymer molecules elute from the chromatography in order of decreasing molecular size

convenient technique for characterizing the complete molecular weight distribution of a polymer.

Question 14

What is XRD and what information does this technique provide

Answer 14

Difraction of X-Ray Crystalline Diffraction

• tell you what a materials crystal lattice structure may be….
  does this by….
  -bombarding x-rays on crystal structure
  -based on crystal structure- x-rays are refracted
  -how they are refracted gives data into peaks
  -more peaks=material has more crystalline structure within the material
  -get peaks and compare them to other known peaks of similar crystalline structures