Elastomers

Question 1

What are the 2 types of elastomers?

Answer 1

Poly-ethers
Addition silicones

Question 2

What is the definition of elastic behaviour?

Answer 2

ability of a deformed material body to return to its original shape and size when the forces causing the deformation are removed.

Question 3

How are elastomers formed and what does this generate?

Answer 3

Formed by polymerisation and cross-linking of polymer chains
Cross-linking generates elastic properties

Question 4

What are the 3 characteristics of elastomers that affect the accuracy by which the SURFACE features are recorded?

Answer 4

Surface detail reproduction
Flow/ viscosity
Contact angle/ wettability

Question 5

What are the 3 characteristics of elastomer that affect the accuracy of DIMENSIONS AND SHAPE of the final impression?

Answer 5

Elastic recovery
Stiffness (flexibility)
Tear strength

Question 6

What does the shark fin test test?

Answer 6

Relates to the ability of IM to deal with undercuts

Question 7

What test test the hardness of an IM?

Answer 7

Shore A hardness

Question 8

What is meant by a low contact angle?

Answer 8

Large % of volume makes contact with the target surface = ideal