resin base material

Question 1

what are the classifications of acrylic resin

Answer 1

1. heat cured
2. autopolymerised
3. light cured

Question 2

What are some examples of heat cured resin

Answer 2

powder: poly methyl methacrylate ganules ( inititated by benzoyl peroxide)

liquid: methyl methacrylate, inhibitor: hydroquinone which extends shelf life
cross linking agent is glycol dimethyacrylate

Question 3

what happens to mechanical properties when there is a dry mix

Answer 3

decreases due to increase porosity

Question 4

how to ensure adequate wetting

Answer 4

add powder to liquid

Question 5

what is the working time at the dough stage

Answer 5

5mins

Question 6

how should you cure heat cured AR

Answer 6

74 deg, place in cold water and increase tempslowly to prevent internal stress, distortion, cracking and crazing.

Question 7

why would there be porosity

Answer 7

vapourisation of unreacted monomer and low mw polymer

• lack of dough homogeneity

Question 8

what cause crazing

Answer 8

increase stress, incorporation of water, can decrease crazing by cross linking( glycol dimethacrylate)

Question 9

how much shrinkage is decreased whend polymer granules are incorporated

Answer 9

8%

Question 10

what are the properties of MMA

Answer 10

high proportional limit and elastic material

can resist fracture under normal usage

low abrasion resistance

Question 11

what does the liquid in autopolymerised acrylic resin contain

Answer 11

tertiary amine which is the activator, activate benzoyl peroxide

Question 12

how does autopolymerised acrylic resin compare w heat cured

Answer 12

lower processing shrinkage, better dimensional stability

lower degree of conversion of monomer

lower initial strength

greater porosity

high water sorption

poor colour stability