Harry J's Hydrogel Seminar

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DEPARTMENT OF SCIENCE LABORATORY
TECHNOLOGY SCHOOL OF APPLIED SCIENCE AND
TECHNOLOGY AUCHI POLYTECHNIC, AUCHI TOPIC A
PREVSUPERABSORBENT HYDROGEL EHIMIKHUAI
HARRISON AST/2191390022 DATE 20TH JANUARY,
2015
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INTRODUCTION

• Hydrogel are cross linked polymer that are
  hydrophilic with carboxylic acid groups.
  Hydrogels are formed by cross linking polymer
  chains through physical, ionic or covalent
  interactions and are well known for their
  ability to absorb water. They are able to absorb
  500 times its weight (from 30 to 60 times its own
  volume) and can become up to 99.9 liquid, but
  when put into a 0.9 saline solution, the
  absorbency drops to maybe 50 times its weight.
  Superabsorbent ability to absorb water is a
  factor of its ionic concentration of the aqueous
  solution in deionized and distilled water.

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PRODUCTION

• Superabsorbent polymers are made using one of
  three primary methods gel polymerization,
  suspension polymerization or solution
  polymerization. Each of the processes have their
  respective advantages but all yield a consistent
  quality of product.
•  COPOLYMER CHEMISTRY
• This involves the polymerization of acrylic acid
  blended with sodium hydroxide in the presence of
  an initiator to form a poly-acrylic acid sodium
  salt (sometimes referred to as sodium
  polyacrylate).

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GELPOLYMERIZATION

• A mixture of frozen acrylic acid, water,
  cross-linking agents and UV initiator chemicals
  are blended and placed either on a moving belt or
  in large tubes. The liquid mixture then goes into
  a "reactor" which is a long chamber with a series
  of strong UV lights. The UV radiation drives the
  polymerization and cross-linking reactions. The
  resulting "logs" are sticky gels containing
  60-70 water. The logs are shredded or ground and
  placed in various sorts of driers.
• Additional cross-linking agent may be sprayed on
  the particles' surface this "surface
  cross-linking" increases the product's ability to
  swell under pressure. The gel polymerization (GP)
  method is currently the most popular method for
  making the sodium polyacrylate superabsorbent
  polymers now used in baby diapers and other
  disposable hygienic articles.

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SUSPENSION POLYMERIZATION

• The suspension process is practiced by only a few
  companies because it requires a higher degree of
  production control and product engineering during
  the polymerization step. This process suspends
  the water-based reactant in a hydrocarbon-based
  solvent. The net result is that the suspension
  polymerization creates the primary polymer
  particle in the reactor rather than mechanically
  in post-reaction stages. Performance enhancements
  can also be made during, or just after, the
  reaction stage.

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USES / APPLICATIONS OF HYDROGELS

• Hydrogel are used to make soft contact lenses
• Wound Dressing
• Baby Nappies, Diapers and Adult Sanitary Pads
• Drug Delivery
• Frog tape (high tech masking tape designed for
  use with latex paint).
• Magical effects such as artificial snow
• Superabsorbent hydrogel is also used for blocking
  water penetration in underground power. Control
  of spill and waste aqueous fluid, artificial snow
  for motion picture and stage production.
• Applicable in wires and cables.

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HYDROGEL PRODUCT SENSITIVITY TO ENVIRONMENTAL
CONDITIONS
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SWELLING MEASUREMENTS

• The equilibrium swelling capability is measured
  by carefully weighing the samples before and
  after immersion in distilled water for about 24
  hours. The swelling ratio (SR) is expressed as
• Where
• Ws - weight of the swollen hydrogel
• Wd - weight of the dried sample.
• Absorbency Under Load (AUL) or Absorbency
  Against Pressure (AAP) is also a property for
  measurement of its swelling ratio The dried
  polymer particles are then screened for proper
  particle size distribution before packaging.

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ILLUSTRATION
Bhat et al, (2006).
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CONCLUSION

• It is concluded that Hydrogel is of utmost
  importance in almost every sector of
  technological advancement such as
• Agriculture
• Biology
• Chemistry
• Industrial Physics
• Its has been able to improve and sustain man in
  his environment against other forms of distress.

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THANKS FOR LISTENING