elastomers-160226225508.pptvegegrhetuetjng

rubber material

1. ELASTOMERS
CONTENTS
•What are elastomers
•Explanation
•Types of elastomers
•Advantages & disadvantages
•Uses & applications

2. ELASTOMERS….?
•Macromolecular material which returns
rapidly to approximately its initial
dimensions and shape after deformation
by a weak stress.
•Or
•An elastomer is a polymer with the
property of elasticity.

3. •An elastomer is a polymerwith the
property of viscoelasticity(colloquially
"elasticity"), generally having notably low
Young's modulusand high yield strain
compared with other materials.

4. •Elastomer is a big fancy word, and all it
means is "rubber". Some polymers which
are elastomers include polyisopreneor
natural rubber, polybutadiene,
polyisobutylene, and polyurethanes.

5. EXPLANATION
•Why elastomer ?
•Structure
•Properties of elastomers
•Effects of stress
•Vulcanization

6. WHY ELASTOMER ?
•HIGH ENERGY DENSITY
–capable of storing large amounts of energy
with small area and volume
•LOW STRAINS
–stress/strain profile suitable for low-power
electrostatic actuators with large
displacements.

7. STRUCTURE
•Thelongpolymerchainscross-linkduring
curing.Themolecularstructureofelastomers
canbeimaginedasa'spaghettiandmeatball'
structure,withthemeatballssignifyingcross-
links.

8. PROPERTIES
•Highlyamorphousmaterials
•Highrandomlyorientatedstructure
•Largereversibleextensions(several
hundredpercent)
•Lowintermolecularforcesallowfor
flexibility
•Rubberoidmaterial
•A'spaghettiandmeatball'structure,with
themeatballssignifyingcross-links

9. GLASS TRANSITION
TEMPERATURE
•glasstransitiontemperature,orTg.Thisis
thetemperatureabovewhichapolymer
becomessoftandpliable,andbelow
whichitbecomeshardandglassy.
•If Tg above room temp
•......................THERMOPLASTIC
•If Tg below room
temp......................ELASTOMER

10. STRETCHING:
•Elastomerscanbestretchedtomany
timestheiroriginallength,
BOUNCING:
•Elastomerscanbouncebackintotheir
originalshapewithoutpermanent
deformation.

11. CROSS LINKING
•Crosslinkingmeansthatdifferentchains
ofpolymermoleculeshaveallbeenlinked
•Advantage
•Disadvantage

12. Elastomeric Materials
•Highly amorphous
•Highly random orientation
•High elongation

13. Elastomeric Materials
•Elongation at break

14. Stress
Strain Elastomeric Materials
•Metals
•Conventional Plastics
•Elastomers

15. Elastomeric Materials
•No Stress
•Stressed
•In tension

16. EFFECTS OF STRESS
•These materials show very little strain
under weak deformation stresses.

17. VULCANIZATION
Rubber ball obtained from
a vulcanization process
Vulcanizationisachemicalprocessfor
convertingrubberorrelatedpolymersintomore
durablematerialsviatheadditionofsulfuror
otherequivalent"curatives".

18. TYPES OF ELASTOMERS
•General-purpose Elastomers.
•Specialty Elastomers
•Thermoplastic Elastomers

19. General-purpose Elastomers.
•General-purpose elastomers include:
•STYRENE-BUTADIENE RUBBER (SBR)
•POLY-BUTADIENE RUBBER (BR)
•POLYISOPRENE (PIR)
•NATURAL RUBBER (NR)
•SYNTHETIC RUBBER (SR)

20. SPECIALTY ELASTOMERS
•Specialty elastomers include:
•NITRILE RUBBER (NBR)
•BUTYL RUBBER (IIR)
•SILICONE RUBBER
•FLUOROCARBON RUBBERS
•URETHANE RUBBER (UR)

21. Thermoplastic Elastomers
•THEY INCLUDE:
•ALIPHATIC THERMOSET ELASTOMERS
•POLYAMIDE ELASTOMERS
•POLYPROPYLENE ELASTOMERS
•OLEFIN ELASTOMERS (TPO)

22. NATURAL RUBBER (NR)
•Naturalrubberisa
productextracted
fromthelatexof
therubbertree.
Natural rubber
occursinalmost
2000plantspecies,
butonlyafewof
them are
industrially
Trans-polyisoprene

23. Natural Rubber
•Raw material extracted from trees

24. Natural Rubber
•Material is processed

25. Natural Rubber
•Latex is then dried, sorted and smoked

26. PROPERTIES OF NATURAL
RUBBER
•Hightensileandtearstrengths
•Resistancetowear,,abrasionandfatigue
•Highmolecularweight
•Rubberiswaterrepellent
•Itshowsresistanttoalkaliesandweak
acids

27. POLY-BUTADIENE
RUBBER (BR)
•Butadiene(ch2=ch−ch=ch2)isproducedby
thedehydrogenationofbuteneorbutaneor
bythecrackingofpetroleum.

28. PROPERTIES OF BR
•Goodabrasionresistance
•Elasticityandcoldproperties
•Lowercost(allsyntheticfromcheap
monomer)
•Widelyusedintyres
•becauseofthegood
abrasionresistance.

29. Styrene Butadiene Rubber (SBR)

30. Silicone Rubber
•Silicone rubber is
based onpolymeric
chains featuring the
very stable,
alternating
combination of silicon
(si) and oxygen (o)
atoms in the
backbone and a
variety of organic side
groups attached to the
silicon atoms.
c
o
H
S

31. PROPERTIES OF SR.
•The silicon rubbers have very low glass
transition temperatures
•Very high temperature resistance
•Low temperature flexibility
•Good electrical resistance

32. Silicones

33. BUTYL RUBBER (IIR)
•Butyl rubber is a
copolymer of
isobutylene with a
small percentage
of isoprene (0,5-
3%) to provide
sites for curing. It is
polymerized AT
LOW
TEMPERATURES.

34. PROPERTIES OF IIR.
•Very low gas permeability
•Very high damping properties (energy
absorption)
•Excellent ageing stability
•Poor resistance to oils and fuels
•Low adhesion properties
•Good weathering resistance

35. THERMOPLASTIC
ELASTOMER (TPE)
•Theyareaclassofcopolymersora
physicalmixofpolymers(usuallyaplastic
andarubber)whichconsistofmaterials
withboththermoplasticandelastomeric
properties
•Sometimesreferredtoasthermoplastic
rubbers

36. Properties of TPE
•Highelasticproperties
•Thermoplasticelastomerpolymersisa
weakerdipoleorhydrogenbonded
•Highmolecularweight
•Highstrenghtduetovulcanization

37. USES OF ELASTOMERS
•Their common uses are as
•In buildings as sealing agent
•In preparing nylon
•In tires
•In industries
•In gaskets

38. •Styreneblockcopolymersareusedin
shoesolesfortheireaseofprocessing,
andwidelyasadhesives

39. •Thesematerialsfindlargeapplicationin
theautomotivesectorandinhousehold
appliancessector

40. •Elastomerscanbe"compounded"or
joinedwithothermaterialstostrengthen
certaincharacteristics.caneasilybe
installednexttovariousothermaterials,
suchasmetal,hardplastic,ordifferent
kindsofrubber,withexcellentadherence.

41. •Elastomersbeingverystrongwhenstruck,
hardifscratched,resistanttocorrosion
fromvariouschemicals,andresilientinthe
faceofhumidityorwatersubmersion,good
electronicinsulators.Betweendifferent
branchesofwires,theyaredenseand
protective.

42. •Theyareeasytosculptwhentheyarein
theirsoftened,resinousstate.Yetonce
theyharden,theyremainimperviousto
changesinmostchangesintemperature
aswellasstresslikestretchingor
compressing.

43. •Elastomersformvariousrubberyshapes.
Manyindustriesrelyonpartsmadefrom
elastomers,especiallyautomobiles,
sports,electronics,andassemblyline
factories

44. •TPEiscommonlyusedtomake
suspensionbushingsforautomotive
performanceapplicationsbecauseofits
greaterresistancetodeformationwhen
compared toregularrubber
bushings.

45. •Usedinadhesives,paints(e,gcar
coating).
•Usedincableinsulation

46. •Elastomersaregoodatinsulating,
withstandingdeformation,andmolding
intodifferentshapes.Usedforwheelsona
skateboardandthesolesoftennisshoes,
totheinsulationcoveringspeakercables
andtelephonelines.

47. ADVANTAGES &
DISADVANTAGES
ADVANTAGES
•These are recyclable like plastics
•They can be easily colored by most types
of dyes
•They offer better durability
•They are resistant to emulsification in
damp conditions

48. •Little or no bending
•Simpler processing
•They have less shrinkage
•Better quality control cost
•With no need to add stabilizers or cure
systems
•It consumes less energy and more
economical control of product quality is
possible.

49. DISADVANTAGES
Elastomer has some disadvantages as
•Much expensive
•General inability to bear load
•Sometimes poor chemical and heat
resistance
•Can be easily distorted
•Sometimes low thermal stability.

50. •Preventing from being used in high speed
automobile tires
•Relatively high cost of raw materials
•Poor chemical and heat resistance
•High compression set and low thermal
stability.

51. •Relativelyhighpricesperweight
•Relativelyhighcostofrawmaterials
•Meltingatelevatedtemperatures
•Newtechnologyunfamiliartomanyrubber
processors