Film formation
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Transcript of Film formation
FILM FORMATIONIN COATINGS
PROVIDED BY :
EMAD BEHDAD
INTRODUCTION
THE MOST IMPOTRANT STEP IN ANY COATING PROCESS
THIS IS THE CONVERSION OF THE COATING FROM LIQUID TO SOLID
FILM FORMATION BEHAVIOUR AND POLYMER GLASS TRANSITION TEMP
PLAY A SIGNIFICANT CHANGE IN THE PROPERTIES OF A POLYMER
THERMOPLASTIC COATINGS
What are the thermoplastics? • Commonly referred to as “plastics”.
• Melt on heating and re-solidify on cooling.
• Common plastics are polyethylene, polypropylene, nylon, PVC etc.
• Used mostly for moulding into articles such as bottles, caps and components or by extrusion into packaging, carrier bags, pipes and fibers etc.
PolymersCross-Linking Polymers
Bonds formed between
polymer chains make the
polymer stiffer.
Natural rubber is too soft and
chemically reactive to
make a useful material.
By vulcanizing the rubber
(cross-linking the polymer
chains) useful materials are
made.
Rubber is usually cross-
linked with sulfur.
Cross-Linking Polymers
Thermal Behavior of Polymers
Glass Transition Temperature (Tg)
At low temperatures, all amorphous polymers are stiff and glassy, sometimes
called as the Vitreous State, especially for inorganic polymers.
• On Warming, polymers soften in a characteristic temperature range known as the
glass-rubber transition region.
• The glass transition temperature (Tg), is the temperature at which the amorphous
phase of the polymer is converted between rubbery and glassy states.
• Tg constitutes the most important mechanical property for all polymers. In fact,
Glass transition
The temperature above which the glass becomes soft and viscous
enough to work is related to the glass transition temperature, Tg.
Below the glass transition temperature, the material is
relatively hard and stiff; above it, it becomes more viscous.
This shows up in the volume/temperature curve.
Effects of tg on volume and modulus
Sol-Gel Processing
• larger variety of precursors
• many processing options
preparation of inorganic-organic hybrid materials possible
low thermal stress of the substrate
simple coating techniques
SOL GEL PREPARATION
Sol-gel processing scheme
Sol-gel facilities
Coating techniques
Dipping
Spraying
Doctor bladingPainting
Rolling
Flow coating
spin coating
DIP COATING
REFERENCES
Journal of Sol-Gel Science and Technology
WWW.ANAVILLAFRANCA.COM
Handbook of Sol-Gel Science and Technology
THANKS FOR YOUR ATTENTION