2. INTRODUCTION
SBR is the co-polymer of styrene and butadiene
It widely used rubber due to its low cost and good properties
SBR produced by solution and emulsion process
Recent years solution SBR is commonly use
The raw materials are monomers ,emulsifiers ,modifiers ,catalyst ,short stop
,coagulating agent ,antioxidant and antiozonants
3. MONOMER PREPERATION
STYRENE- styrene prepared by dehydration of ethyl benzene
BUTADIENE –prepared by dehydration of butane
Ion oxide or chromia alumina used as catalyst
4. POLYMERISATION
The polymerization leads to 3 varieties cis , trans and vinyl
Solution SBR contain higher cis , lower trans content low vinyle content
,linearity and molecular weight distribution compared to emulsion SBR
5. EMULSION POLYMERISATION
Emulsion protect the initiator from termination so E SBR give high molecular
weight and act as good heat transfer medium
The removal of unreacted monomer is easier than others
monomer ,water ,emulsifier and initiator added to reactor
Potassium peroxydisulfate used as initiator
Soap used as emulsifier
For cold SBR reaction done at 5 digree Celsius and hot SBR reaction done at
50 degree Celsius
After reaching 70 to 75 % conversion short stop added to terminate reaction
and control molecular weight
6. cont
Hydroquinon used as short stop
N phenyl beta napthalamine used as antioxidant
For cold SBR
phosphate EDTA used as buffer
Ion and hydro peroxide used as initiator
In these method colored product can be made
The disadvantage is polymer have limited molecular weight
7.
8. SOLUTION SBR
The polymer have narrow molecular weight distribution
Less chain branching and high cis content
Abrasion resistance ,less heat build up ,high resilience and better flex
resistance
Lithium and alkyl lithium used as catalyst
Molecular weight controlled by catalyst level and temperature
9. PRPERTIES
Tg of E SBR IS 50 degree Celsius and Tg of solution SBR slightly less than E SBR
Number average molecular weight of E SBR 80000 to 110000 and solution SBR
1001000
Weight average molecular weight of E SBR IS 3.2 to 4 lack
10. COMPOUNDING AND
PROCESSING
Superior extrusion property than NR
Processing similar to NR
Compounding ingredients are sulphur ,antioxidant ,antioxonant ,activator,
accelerator , soaftners ,extenders ,fillers,
11. APPLICATIONS
The main application of SBR is automobile tyre tred
It is the widely used synthetic rubber occupy half of synthetic rubber
It replace NR many applications
