Castor oil-urethane acrylate (CVA) oligomers have been synthesised and char
acterised by intra-red spectroscopy (FT-IR), gel permeation chromatography(
GPC) to study the relationship between the reaction kinetics and the struct
ure of the products. It is shown that the chain terminating reaction betwee
n 2,4-toluene diisocyanate (2,4TDI) and hydroxyethylacrylate (HEA) to form
isocyanatoethyl acrylate (IEA) obeys a second order mechanism, as does the
chain extension reaction of IEA and castor oil (CAS). From the data of the
polymerisation rate constant and the apparent activation energy, it can be
seen that the different structure of CVA oligomer is dependent mainly on th
e different reactivities of both para and ortho NCO groups in 2,4TDI. Where
as the apparent viscosity of the CVA oligomer is related to the structure o
f diisocyanates. Results from the dynamic mechanical spectrum (DMS, the abs
tract of dynamic mechanical spectrum, a kind of detection method) indicate
that the hard segment content of oligomers is then increased up to 59% (wt.
). A phase-separated structure is formed and leads to the highest tensile s
trength (18.2MPa). When the hard segment content is increased to 67% (wt.),
the dynamic modulus is reduced and the single depletion peak from DMS is e
xhibited at the temperature of 100.7 degrees.