Thermo gravimetric analysis of the CTS-t-ENR
The TG curve and DTG curves of CTS, and CTS-t-ENR biocomposites
at different CTS loadings: 0 phr, 2.5 phr, 5 phr, 10 phr
and 15 phr are depicted in Figs. 6 and 7. DTG curve of CTS exhibits
mass loss at two stages. The initial mass loss of 12% occurred within
40 and 240 C due to loss of solvent molecules (water and acetic
acid). The second stage shows a mass loss of 52% within 240 and
400 C due to degradation (via chain scission) of CTS [18]. The DTG
curve of 0phrCTS-t-ENR exhibits one-step degradation process with
rapid weight loss of 43% at 402 C. The major mass loss occurred
within 310 and 570 C is 95% due to the total pyrolysis (decomposition
of the hydrocarbon in nitrogen atmosphere) of the rubber
matrix. The amount of char residue deduced from the TG curve of
0phrCTS-t-ENR beyond 600 C is about 4.5%. The amount of char
residue deduced from the TG curve of CTS beyond 600 C is about
33.8% which is quite substantial compared to that of ENR50.
However, from the view point of thermal stability it is of interest to
note that within 270 and 340 C only about 1% of 0phrCTS-t-ENR
degraded whereas CTS degraded by about 38%. Therefore, 0phrCTSt-
ENR is thermally more stable than CTS.
From the DTG curve, it is noticeable that all the biocomposites
with 2.5 phr and 5 phr loading of CTS have a two-step degradation
process with rapid weight loss of 80% in the region 250e440 C. The
mass loss of the composite within the range of 40 C and 150 C is
from the volatile materials and the major weight loss occurred
within the range of 330e594 C with weight loss of about 80e90%.
This indicated that at lower CTS loading there is an interaction
between the rubber and CTS which supports our tensile data.
Where else biocomposites with 10 and 15 phr loading of CTS
have three degradations step. The first step between 40 C and
150 C and the second step around 250e330 C corresponds to
5e6% mass loss, which is due to the destruction of amino groups
[19]. The major weight loss occurred within the range of
330e594 C with weight loss of about 80e90%. The char residue of
the biocomposites increases as the CTS loading increase. It is also
expected that the char produced will form a better protective layer
on the surface of the ENR, which raised the decomposition of the
composite to a higher temperature. The addition of CTS to the
rubber reduces the thermal stability of the composite. As the CTS
loading increases the thermal stability reduces.