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