polymers Flashcards
what are polymers?
many monomer units chemically joined together
how reactive are simple poly(alkenes)?
unreactive
what is the backbone of a poly(alkene) made up of?
single C-C bonds and so are saturated
what do the properties of poly(alkenes) depend on?
their structure and the intermolecular forces between neighbouring polymer chains
what forces do neighbouring chains of poly(ethene) have? what does this mean for the properties ?
Van der waals
properties of polymers like this one can be modified by increasing branching which decreases points of contact so VDW are weakened
increasing flexibility and lowering melting point
what are the two types of poly (ethene)?
low density (LDPE) and high density (HDPE)
compare branching, properties and usage of LDPE and HDPE?
LDPE- branched, flexible, carrier bags
HDPE- straight, rigid, crates and pipes
what are the properties of poly (chloroethene) (PVC)?
rigid and brittle
why is PVC rigid and brittle?
polar C-Cl bonds and therefore has permanent dipole- permanent dipole forces between polymer chains
what can be added to PVC to make it more flexible and why?
small molecules called plasticisers because they get in between neighbouring chains and reduce intermolecular forces, allowing them to slide over each other.
compare properties and uses of unplasticized poly (chloroethene) (U-PVC) with plasticized poly (chloroethene) (P-PVC)?
U-PVC: rigid, window frames
P-PVC: flexible, clothing and flooring
what is an example of a plasticiser?
Esters such as tributyl citrate
when do we use the ()n for drawing polymers and when do we not?
“write an equation for the formation of PVC” = YES
“draw the repeating unit of PVC”= NO
what do we use poly(propene) for and why?
food containers because it has good fatigue, heat and chemical resistance, and is rigid.
what is another name for poly (tetraflouroethene)?
teflon
what is the use for teflon?
non-stick coating
