Fig. 3. shows effect of coagulation systems on particle size of the skim latex (SL) and skim latex with
ammonium polyacrylate solution (SL+NHPA). It is seen that the particle size distribution of the skim latex with and
without NHPA is very similar. Therefore, incorporation of NHPA did not effect on the size of the rubber particles.
Fig. 3.
Particle size distribution of skim latex (SL) and skim latex with ammonium polyacrylate solution (SL+NHPA).
Coagulation
Table 1 shows lower amount of sulfuric acid was used to coagulate the latex compared with the system
using concentrated sulfuric acid and 10 wt% sulfuric acid. However, higher pH after coagulation and amount of
recovered skim rubber were observed in particular the latex with incubation time of 3 h. The skim latex coagulation
for 3 systems are shown in Fig. 4.
Table 1
Effect of coagulation systems and incubation times on pH after coagulation and level of recovery of skim
rubber.
Samples
concentrate of
H
2
SO
4
Incubation
Times (h)
Volume of 98%
H
2
SO
4
(ml)
pH value after
coagulation
% Recovery
SR
a
98 wt%
0
25.0
1.52
77.27
10 wt%
0
11.1
3.48
94.62
SR+NHPA
b
10 wt%
0
10.0
4.45
96.02
1
4.41
96.41
3
4.35
97.04
6
4.30
95.95
12
4.30
96.76
24
4.23
96.80
a
Skim rubber,
b
Skim rubber with ammonium polyacrylate solution
