Polymers 2.02 Flashcards
What are some advantages and disadvantages of polymers materials?
Advantages
-User friendly
-Chemical resistant
-Durable
-Mechanical properties
*Strength
*Ductility
-Cheap
-Shapeable
Disadvantages
-Flammable
-Creep
-Difficult to recycle
What are the classifications of the polymers regarding their structure?
-thermoplasts
-thermoplastic elastomers
-elastomers
-duromers
Properties of a Semi-crystalline polymer
-Tg+ melting temperature (Tm)
-strong interactions
-high strength
-higher ductility
-higher thermal stability
Properties of a amorphous polymer
-“frozen” or “glassy state”
-glass transition temperature (Tg)
-Isotopic
-often brittle
What is the glass transition temperature (Tg)?
softening; below this temperature no movement of polymeric chains, glassy and brittle behavior
What is the melting temperature (Tm)?
transition temperature, above this temperature melting state, highly deformable.
What is decomposition temperature?
Decomposition of polymer chains, oxyidation.
A strong bond within the polymer chains.
Chemical bond (covalent)
Relatively week force within the polymer chains.
Van der Waals forces
A moderate bond within the polymer chains.
Hydrogen bonds
What is a low cross linking density?
three dimensional network of strong chemical bonds, each 100-1000 monomers
What is a high cross linking density?
dense three dimensional network of strong chemical bonds
Name some polymer additives
-plasticizer: low molecular weight to reduce stiffness and enhance processability.
-solvents: residuals from processing
-pigments: color
-antistatics: electrically conductive fillers
-stabilizers: UV protection
-flame retardants
-filers: minerals
