Polyisobutylene kudzai hamish ruzvidzo

POLYISOBUTYLENE

Polymer SynthesisBy: Kudzai Hamish Ruzvidzo

B Tech (Chemical Process Systems Engineering)M Tech (Polymer Science and Technology)

[email protected]

Introduction• Polyisobutylene is a synthetic rubber, or elastomer• It's special because it's the only rubber that's gas impermeable, that is, it's

the only rubber that can hold air for long periods of time• Because polyisobutylene will hold air, it is used to make things like the

inner liner of tyres, and the inner liners of basketballs. • . Polyisobutylene is a colorless to light yellow viscoelastic material. It is

generally odorless and tasteless, though it may exhibit a slight characteristic odor.

• Polyisobutylene was first developed by the BASF unit of IG Farben in 1931 using a boron trifluoride catalyst at low temperatures and sold under the trade name Oppanol B

Monomer • Polyisobutylene is a vinyl polymer made from the isobutylene monomer• Polyisobutylene is very similar to polyethylene and polypropylene in

structure, except that every other carbon is substituted with two methyl groups

• Isobutylene is a colorless gas with a faint petroleum-like odor

Synthesis• PIB is made from the monomer isobutylene, by cationic vinyl

polymerization.

Polymerization• The polymer is formed by a process called cationic vinyl polymerization and is

highly exothermic. • It involved the use of an initiator or cation, which attracts a pair of electrons

from the carbon-carbon double bond, thus forming a single bond with the initiator.

• One of the carbons, previously double bonded is now positively charged and will react with another monomer, similarly to the initiator.

• The process is repeated the polymer is formed.• The polymerization reaction is usually carried out at temperatures in the

range –100°C to control the reaction rate. At higher temperatures, the reaction proceeds too fast to control.

Mechanism

Properties• Air tight and gas impermeable

• Flexibility

• Good weathering resistance

• Resistant to ozone

• Good vibration damper

• Biocompatible

Uses • the inner liner of tyres • Inner tubes• inner liners of basketballs, footballs e.t.c• stoppers for medicine bottles and pharmaceuticals• Sealants and adhesives• O rings• Joint replacements (biomedical)• Chewing gum• Tank and pond liners• Speaker surrounds