SYNTHESIS, CHARACTERIZATION, AND PROPERTIES OF RUBBER LATICES A RVIEW

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POLYMER RESEARCH LABORATORY
SYNTHESIS, CHARACTERIZATION, AND PROPERTIES OF
RUBBER LATICES (A RVIEW)
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POLYMER RESEARCH LABORATORY
Project Director Prof. Dr. Tahir
Jamil Researcher (Chemical Engineer) Engr.
Shahzad Maqsood Khan
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INTRODUCTIONLATEX
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• A stable dispersion of polymeric material in an
  essentially natural or synthetic colloidal
  suspension.

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INTRODUCTION
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HISTORY
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• Europeans get Latex when Columbus came to the
  Americas in 1492
• In 1770, English chemist Joseph Priestly gave the
  name rubber.
• Mesoamerican Columbian civilizations get
  familiar with Latex in 1600 BC
• First emulsion polymerized SBR was in 1930
• U. S. Government in 1940 established the Rubber
  Reserve Company
• Cold polymerized E-SBR was developed in 1947.

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CLASSIFICATION
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DIFFRENCE B/W LATICES POLYMER SOLUTIONS
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• Latices remain in the fluid from even at high
  concentrations.
• Polymer deposited from latices have
• High molecular weight
• High modulus
• High resistance to deteriorative influences
• latices need extra and slow drying than polymer
  solutions.
• Latices thermodynamically unstable and variable.

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DIFFRENCE B/W NATURAL SYNTHETIC LATICES
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• Latices Have
• Complex geometrical forms.
• Large particle size
• High wet gel strength
• Time of drying is also lower
• Dry deposits of latices dont absorb water
• Natural rubber latices are non resistant to
  coacervation by high speed stirring
• Chemical composition of the natural rubber
  latices are complex
• Spontaneous coagulation takes place

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Types of latices
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NATURAL LATEX SYNTHESIS
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• Latex is a milky sap found in the cells of
  certain plants (Hevea Brasiliensis) contains
  30-45 rubber contents.

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NATURAL LATEX SYNTHESIS
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• Steps Included
• Planting
• Tapping
• Traditional tapping
• Preservation
• Fine tapping
• Producing liquid concentrate
• Final product through polymerization
  ingredients preservatives, vulcanizing agents etc
  are added
• Drying sheets or stocks (by extrusion)

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SYNTHETIC LATEX SYNTHESIS
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LATEX SYNTHESIS
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CONTRAST B/W LATEX SOLID POLYMER TECHNIQUES
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• Latices require relatively light and simple
  machinery so capital outlay is relatively low.
• Less processing steps involved.
• Solid articles of thick section difficult to make
  as latices shrink on drying.

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PROPERTIES OF LATICES
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OBERVABLE PROPERTIES OF LATICES
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COLLOIDAL PROPERTIES OF LATICES
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POLYMERIC PROPERTIES OF LATICES
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TECHNIQUES FOR DETRMINATION OF COLLOIDAL
PROPERTIES
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• Electron Micrograph
• Soap Titration
• Turbidity
• Centrifugation

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PROCEDURES TO DETERMINE QUALITY OF NATURAL LATEX
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• Determination of total solid contents (TSC) of
  latex.
• Determination of dry rubber contents (DRC) of
  latex.
• Measurement of surface tension.
• pH measurements.
• KOH number.
• Measurement of mechanical stability.
• Viscosity.
• Density.
• Coagulum concentration.
• Copper concentration.
• Manganese concentration.
• Pre vulcanization test.

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STABILITY OF LATEX
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• Latex stability has distinct aspects
• Latices interaction with the aqueous phase.
• Polymeric particles interaction with each other.
• Reduction of the free energy.
• The presence of the electric charges.
• The presence of water molecules around the
  polymeric particles.

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DESTABILIZATION AND COASERVATION OF LATEX
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• Coaservation
• A process which destabilizes the latex to such
  an extent that the particles agglomerate and
  coalesce in large numbers.

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DESTABILIZATION AND COASERVATION OF LATEX
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• Coaservation results in formation of
• Gel.
• Coagulum.
• Mass of Flocks

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COASERVANTS
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LATEX COMPOUNDING INGREDIENTS
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• Typical Formulation for Latex synthesis
• 20-60 monomer
• 18- 100 or more Water
• 2-10 wt of emulsifier
• 0.1-1.0 wt initiator
• 0.1-1.0 wt chain transfer agent

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LATEX COMPOUNDING INGREDIENTS
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• Buffers
• Bacteria control agents
• Viscosity modifiers and protective
• collides or thickeners
• Pigments
• Softeners or stiffeners
• Micelle generators
• Antioxidants
• Surface active agents
• Modifiers
• Short stoppers

• Accelerators
• Accelerators activators
• Antioxidant synergists
• Fillers
• Preservatives
• Antifoaming agents
• Tackifiers
• Deodorants
• Antiozonants
• Stabilizers
• Fire retardants
• Vulcanizing agents or cross linkers

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APPLICATIONS
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• Disposable gloves in medical industry
• Adhesives
• Sealants and coatings
• Foam products
• Dipped goods
• Casting
• Rug
• Carpet backing
• Fabric back-coating
• Paper saturation
• Beater addition
• Paper coatings
• Paints
• Binders
• Leather finishes
• Floor polishes
• Waterproof clothing

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APPLICATIONS
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• Floccing
• Latex thread
• Can closure
• Thickeners
• Box toes and shoes counters
• Sealant and mastics
• Chewing gum
• Modifiers
• Extrusion
• Molding
• Protein reduction
• Enzyme treatment
• Finished product treatments
• Glove coating
• Peroxide vulcanization
• Cement and asphalt
• Bounded fibers
• Pigment printing

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ACKNOWLEDGEMENTS
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• This work is supported by HEC, Pakistan.
• Miss Saba Bahzad (ICET PU LHR)
• Mr. Muhammad Aslam Butt of Reliance Polymer
  Industries Lahore
• Dr. Khurram Khawaja and Mr. Muhammad Tahir Butt
  of Anwar Khawaja Industries Sialkot
• Mr. Ibrar Mr. Naveed of Shafi Reso Chem Lahore

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• THE END
• WITH
• THANKS TO ALL PARTICIPANTS