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17 Cards in this Set

  • Front
  • Back
What is adhesion?
Process by which two initially separate
surfaces (adherend) are held together.
What is an adhesive?
substance that cause two surface to stick
together.
How can adhesion be achieved?
using adhesive or heat sealing
What are the mechanisms for adhesion?
inter molecular forces between adhered and adhesive
What are cohesive and adhesive forces?
for adhesive forces: forces of attraction between adherend and adhesive. (Acts at the interfaces)

for cohesive forces: forces of inter molecular attraction acting within a material. (Acts within the material)
What is the condition to achieve maximum adhesion?
Max adhesion when adhesive forces are greater than cohesive forces.
List 3 factors to achieve good adhesion.
surface tension, solubility parameter, surface tension
What is a reactive adhesive?
an adhesive that reacts basically by chemically bonding or under going a chemical reaction
What is the difference between water borne and solvent borne adhesives?
solvent is a base polymer and other components dissolved in an organic solvent
water is a base polymer and other components dissolved in water
What are Pressure Sensitive Adhesives?
Used when surfaces are mated under briefly applied
pressure at room T.
What is heat sealing?
Process by which two structures containing
at least one thermoplastic layer are sealed by the
action of heat and pressure.
What are the four additives for adhesives and what do they do?
Tackifier - improve stickiness
Solvent - modifiy viscosity
Fillers - solid inclusions to reduce cost
Primer - to improve bonding strength of adhesive
What is dwell time?
time during which external pressure holds the two structures together.
What are the two kinds of heat use to heat the surface of plastic?
Conduction and radiation
What is the difference between supported structures and non supported structures?
Non-supported don't have a solid layer (such as alum), supported does
what is the difference between bar and thermal sealing method?
thermal just used heat and pressure
What is hot tack?
Strength of heat seal measured before the seal is cooled