condensation elastomers lecture by dr veena paul

1. CONDENSATION POLYSILICONES

2. Elastomers
• Synthetic rubber based materials
• No water involved in setting reaction NON-AQUEOUS
ELASTOMERIC IMPRESSION MATERIALS

3. CLASSIFICATION OF ELASTOMERS
BASED ON
VISCOSITY/CONSISTENCY
• LIGHT BODY
• MEDIUM/REGULAR BODY
• HEAVY BODY
• PUTTY
A/C TO
POLYMERISATION
• CONDENSATION POLYMERISATION- POLYSULFIDES ,
POLYSILICONES
• ADDITION POLYMERISATION- ADDITION POLYSILICONE
• IONIC RING OPENING POLYMERISATION- POLYETHER
• VISIBLE LIGHT CURE POLYMERISATION- POLYETHER

4. CONDENSATION POLYSILICONES
Are silicone rubbers based on condensation reactions.
Not very popular these days due to advent of better elastomers.Also
called RTV (Room temperature vulcanization )silicones.
Available as two pastes or paste-liquid systems in low, medium,high or
putty consistencies.

5. COMPOSITION

6. Setting reaction
• It is a condensation reaction occurring at ambient temperature.
BASE PASTE + REACTOR PASTE---- POLYMERISATION REACTION INVOLVING
TETRA ETHYL ORTHOSILICATE IN PRESENCE OF TIN OCTATE
ELASTOMER FORMS THROUGH CROSSLINKING BETWEEN TERMINAL
SILICONE POLYMER AND ALKYL SILICATE GROUPS TO FORM 3D NETWORK
ETHYL ALCOHOL – BY PRODUCT(Evaporation causes contraction of set
silicone)

8. MANIPULATION
• PASTE AND LIQUID- MIXING PAD…UNIFORM BLENDING
• PUTTY AND LIQUID-KNEADED
• TWO PASTES SYSTEM- MIXING PAD- VISCOSITY DIFFERENCES
COMPENSATED

12. USES:
• FIXED PARTIAL DENTURE IMPRESSIONS
• INLAY,ONLAY IMPRESSIONS
• IMPLANT IMPRESSIONS