Effects of Gamma Radiation on the Physicochemical Properties …
23
Fig. 2 SEM images of irradiated polyester resin: at 5 kGy (a), and 10 kGy (b)
The effects of the gamma radiation on the thermal properties of polyester–styrene
resin were studied by Thermogravimetric Analysis (TGA). In particular, the decomposition temperature was determined for irradiation doses ranging from 10 to
320 kGy. The results show that 20 kGy are enough for the solidification of
polyester–styrene resin. Moreover, the thermal degradation reaction for a weight
loss of 10% (T10), was obtained around 330 °C, while at 370 °C weight loss was
30%. Thus, after hardening of polyester resin (at 20 kGy), no significant changes
were obtained for the decomposition temperature. In the same study, thermomechanical analyzer (TMA) was utilized to locate glass transition temperature (T g ) of
polyester–styrene resins after irradiating; the measurements were obtained with a
constant force. The results show, T g at 67 °C for an irradiation dose of 20 kGy, and
a slight increase of 11 °C, when applying 320 kGy. Such increase, is due to the
cross-links of polymer chains, which reduces the segmental mobility of the chains
[27].
According to the literature, glass transition temperature, T g , increases when irradiation dose increases. For example, in the case of non-irradiated polyester resins,
The T g was located at 260 °C with a weight loss of 5%, but for irradiated polyester,
T g increases 30 °C. In the case of the decomposition temperature, the values for
both, non-irradiated and irradiated polyester resin, are very similar. Nevertheless,
the values are higher in presence of nitrogen than those obtained in oxygen [28–30].
After irradiating, stiffness of polyester resin gradually increases, as it is shown
in Fig. 3. For non-irradiated resin, smooth surface is obtained, but for an irradiation
dose of 150 kGy, the surface changes, now is more rough with some cracks, which
were obtained after scissions of polymer chains [31].
Mechanical properties or gamma irradiated polyester-styrene resin were evaluated. The results show that the stress at break increases when irradiation dose
increases. At 20 kGy the value is 6.5 MPa, which increase 38% for an irradiation dose of 320 kGy. Polymer chains build cross-links between the chains, thus
the density increases. Such density increases with increasing the irradiation dose.
23
Fig. 2 SEM images of irradiated polyester resin: at 5 kGy (a), and 10 kGy (b)
The effects of the gamma radiation on the thermal properties of polyester–styrene
resin were studied by Thermogravimetric Analysis (TGA). In particular, the decomposition temperature was determined for irradiation doses ranging from 10 to
320 kGy. The results show that 20 kGy are enough for the solidification of
polyester–styrene resin. Moreover, the thermal degradation reaction for a weight
loss of 10% (T10), was obtained around 330 °C, while at 370 °C weight loss was
30%. Thus, after hardening of polyester resin (at 20 kGy), no significant changes
were obtained for the decomposition temperature. In the same study, thermomechanical analyzer (TMA) was utilized to locate glass transition temperature (T g ) of
polyester–styrene resins after irradiating; the measurements were obtained with a
constant force. The results show, T g at 67 °C for an irradiation dose of 20 kGy, and
a slight increase of 11 °C, when applying 320 kGy. Such increase, is due to the
cross-links of polymer chains, which reduces the segmental mobility of the chains
[27].
According to the literature, glass transition temperature, T g , increases when irradiation dose increases. For example, in the case of non-irradiated polyester resins,
The T g was located at 260 °C with a weight loss of 5%, but for irradiated polyester,
T g increases 30 °C. In the case of the decomposition temperature, the values for
both, non-irradiated and irradiated polyester resin, are very similar. Nevertheless,
the values are higher in presence of nitrogen than those obtained in oxygen [28–30].
After irradiating, stiffness of polyester resin gradually increases, as it is shown
in Fig. 3. For non-irradiated resin, smooth surface is obtained, but for an irradiation
dose of 150 kGy, the surface changes, now is more rough with some cracks, which
were obtained after scissions of polymer chains [31].
Mechanical properties or gamma irradiated polyester-styrene resin were evaluated. The results show that the stress at break increases when irradiation dose
increases. At 20 kGy the value is 6.5 MPa, which increase 38% for an irradiation dose of 320 kGy. Polymer chains build cross-links between the chains, thus
the density increases. Such density increases with increasing the irradiation dose.