Chemistry Reference
In-Depth Information
was 376.0
o
C, which was better than that of maleic rosin ester polyol (305.1
o
C)
and commercial polyether polyols 4110 (262.1
o
C). The
T
5%
of hydroxymethyl rosin
polyether polyol decreased with an increase in the added glycerol content, but it was
still higher than 325
o
C when the glycerol content was 25%.
CH
2
OH
CH
2
OH
O
O
O
CH
2
OH
CH
2
OH
+
CH
2
O
CH
2
O
OH
OHOHOH
KOH
OH
COOH
COO
OH
Hydroxymethyl rosin
Rosin based polyether polyols
Figure 3.8
Synthesis of rosin based polyether polyols
3.4 Rosin and Turpentine Interpenetrating Polymer Network
Rosin and turpentine are two components of pine resin, and they are always utilised
separately. As a thermosetting polymeric monomer with a fused ring structure, rosin
gives polymers good heat resistance but may cause low toughness. In our study, we
addressed this problem by introducing an interpenetrating polymer network (IPN) of
rosin-derived epoxies and turpentine-derived polyurethane [13, 14]. A series of IPN
materials, based on a rosin epoxy resin (RER) and a turpentine polyurethane, were
prepared from gum rosin and turpentine oil (
Figure 3.9
). FTIR spectra showed that
the curing rate of the turpentine-based polyurethane was faster than that of the rosin-
based epoxy resin and these two networks formed sequentially but not simultaneously.
The differential scanning calorimetry (DSC) results showed that there was no phase
separation in the final interpenetrating polymer networks as each of these exhibited
a single, broad
T
g
peak. When the rosin-based epoxy resin was 13% by weight, the
T
g
reached a maximum. This was not only due to the best compatibility of the two
components but also the optimum chemical crosslink between the rosin-based epoxy
resin curing agent and isocyanate-turpentine polyester polyol. Rigid rosin-based
epoxy resin and flexible turpentine-based polyurethane could form a tough polymer
network. The test results in
Table 3.4
also showed that the IPN exhibited the optimum
mechanical properties when the rosin-based epoxy resin was 13% by weight.
