Week 11 Semester 2 - Epoxy Resins Flashcards
What is an epoxy resin
Reaction system using a resin and a hardener
what is the characteristic reaction group of an epoxy
It links to the end of the resin chain
synthesis of epoxy resins
two step process
1. Make a diepoxy (above)
2. crosslink diepoxy with a diamine (hardener). this makes the cross-linked network
prepolymer is made using bisphenol A and epichlorhydrin
Process of the diepoxy reacting with the diamine
oxy ring opens, reacting with the amine
in the end, a huge network is formed
in the reaction between epoxy and hardener, what groups are formed, and how do the molecules join together
O- ring open up, producing a lot of OH groups, which are very good for hydrogen bonding. This attracts a lot of water, even though its insoluble
for every crosslink you form, an amine joining to two chains, you form 4 OH groups, a big capacity for attracting…
moisture. relating to the length of the chain, determining the volume between chains, affecting physical properties
DGEBA
Bisphenol A diglycidyl ether: liquid epoxy resin
smaller epoxy resin molecules build ______ network structures with ______ OH group
stiffer, more
Properties of epoxy resins
how can properties of epoxy resins be manipulated with changes to:
resin chain length
more OH groups
TRi- amines as hardeners
Mix ratio
Properties of aliphatic epoxies
they have no ring structures, just have CH2s, which means much less likely to yellow.
How can you use solvents to control the viscosity of an epoxy
what happens when you use Acetone as an epoxy dilutant
uses of epoxy resins in conservation
ageing of epoxy resins
