Elastomers Flashcards
1
Q
Give two examples of elastomers.
A
Polyether (e.g. Impregum) Addition silicones (e.g. Polyvinyl siloxane)
2
Q
What properties should an impression material be assessed on?
A
Flow/viscosity Surface detail (reproduction) Contact angle/wettability Elastic recovery (%) Stiffness (flexibility) Tear strength Mixing time (min) Working time (min)
3
Q
What is viscosity?
A
Measure of a materials ability to flow.
4
Q
What is tensile strength?
A
How well a material can withstand the effects of tearing
5
Q
Why is low rigidity desirable in impression materials?
A
To ease its removal from undercut/interdental regions
6
Q
What is the setting and working times of polyethers?
A
ST - 5 mins
WT - 2 mins
7
Q
What is the setting and working times of addition silicones?
A
ST - 6 mins
WT - 4 mins
8
Q
What is an elastomer?
A
A polymer with viscoelasticity (only partly elastic) and very weak intermolecular forces
