particle in the skim natural rubber latex and the skim natural rubber latex with NHPA were measured by laser
diffraction spectroscopy (Mastersizer 2000, Malvern).
Coagulation
The NHPA solution (10 wt%) at a concentration of 0.2 wt% was added into the skim latex. The mixture was
constantly stirred for 30 min and various incubation times at room temperature for 0, 1, 3, 6, 12 and 24 hr. After that,
coagulated the mixers with 10 wt% sulfuric acid compared with the system using concentrated sulfuric acid and using
solely 10 wt% sulfuric acid.
Results and Discussion
Characterizations
Fig. 1. shows FT-IR spectrum of ammonium polyacrylate (NHPA). It can be seen that absorption bands
shown at 1686 cm
-1
is due to carbonyl groups. The peaks at 1553 and 1405 cm
-1
corresponding to asymmertric and
symmertric stretching vibration of carboxylate groups, respectively. This proves the reaction of ammonium acrylate
monomer to form NHPA, reaction mechanism shown in Fig. 2.
Fig. 1.
FT-IR spectrum of ammonium polyacrylate (NHPA).
CH
2
CH
COO
-
H
+
+
NH
4
+
OH
-
CH
2
CH
COO
-
NH
4
+
+
H
2
O
CH
2
CH
COO
-
NH
4
+
n
K
2
S
2
O
8
70
o
C, 1 h
CH
2
CH
COO
-
NH
4
+
Fig. 2.
Reaction used to prepare ammonium polyacrylate (NHPA).
