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