Butyl rubber is a synthetic rubber that is a copolymer of isobutylene and isoprene. It is produced via cationic copolymerization of 98% isobutylene and 2% isoprene using an initiator like Friedel-Craft acids at low temperatures between -90 to -100°C. Butyl rubber has excellent impermeability and flexibility due to its structure with long polyisobutylene segments separated by double bonds from the isoprene units. It has many desirable properties including low permeability, vibration damping, resistance to aging and weathering, fast cure rates, and being the best sealant of all known rubbers. These properties make butyl rubber useful in various applications

1. Butyl Rubber

2. GROUP 14
ONG HUI JIN 152161
SITI ZAHARAH BT SYED RAMLI 152197
NORASHEILA BT MOHD SAAD 152167

3. INTRODUCTION
•AKA isobutylene- isoprene rubber
• synthetic rubber/ elastomer
• a copolymer of isobutylene with isoprene
•isoprene units: double bond that provides a site for
crosslinking during vulcanisation & located randomly in
the polymer chain
•excellent impermeability& good flex properties -low
levels of unsaturation between long polyisobutylene
segments

4. Figure 1. Structure of butyl rubber.

5. Preparation/synthesis

6. Produced by cationic copolymerization between ≈ 98% isobutylene
&≈ 2% isoprene
Typical method:
Initiator: Friedel-Craft acids(e.gAlCl3)
Medium: methyl chloride (reaction diluent)& boiling liquid
ethylene
Why? To remove the heat of reaction and maintain the needed
temperature (Reaction is highly exothermic)
Temperature: controlled at low temperatures (-90 to -100 °C)
Why? To achieve high molecular weight butyl rubber for application
as rubber)

7. Alternative method:
Initiator: mixture of a major amount of diethylaluminum chloride
& a minor amount of ethylaluminum dichloride( activated by minute
amounts of water / methylaluminoxane (MAO) )
-modified initiators :higher molecular weights, higher degrees of
conversion & higher isoprene contents in the butyl rubber
Medium: hexane
Temperature: -60 °C
- Activation by MAO allow higher polymerization temperature
which does not require much heat removal from reaction mixture

8. Commercial Butyl Rubber polymerization
process

9. PROPERTIES OF BUTYL RUBBER
Low permeability to air, gases and moisture
Vibration damping
 converting the mechanical vibrational energy of solids into heat energy.
Low glass transition temperature
Low modulus elastomer
 Elastomer: able to stretch a long distance and still bounce back
Low compression set
 Compression set: percentage deflection from original shape of a rubber item
having been subjected to a constant compressive load, then released.

10. PROPERTIES OF BUTYL RUBBER cont.
Resistance to aging and to weathering from atmospheric exposure
Wide vulcanization versatility
 Vulcanization: chemical process for converting rubber into a
compound material (polymer) with the addition of sulphur
Fast cure rates
 Cure rates: toughening or hardening of a polymer material by cross-
linking of polymer chains
Processing safety: no nitrosamines or nitrosamines precursors
 Nitrosamines: carcinogenic and can cause cancer

11. PROPERTIES OF BUTYL RUBBER cont.
High extensibility
 Broad range of durometer and tensile strength properties
 Low filler content for specific gravity, cost-effective compounding
Best sealant of all the known rubbers
 Sealant rubber -type of product seals and protects different materials
using rubber-based substances
Blood compatible
 Allows this substance to be used in biomedical applications

12. USES OF BUTYL RUBBER

13. THE END