摘要
用热重-微商热重(TG -DTG )方法研究了在流动的空气状态下 2 种凝固工艺制备的天然橡胶(NR )的热降解动力学,用 O zaw a 方程求取不同转化率 α 时的反应活化能 E,外推至转化率 α 为 0 的表观活化能 Eα→0,并用 Coats-Redfern 方程求取不同的加热速率 β 的反应活化能 E,外推 β 为 0 的表观活化能 Eβ→0。结果表明:甲酸凝固制备的 NR 在空气气氛中热降解反应表观活化能 Eα→0 为 101.6 kJ/mol,Eβ→0 为 104.5 kJ/mol,确定其表观活化能为 101.6￣104.5 kJ/m ol;自然凝固 7 d 制备的 N R 热降解反应表观活化能 Eα→0 为 107.7kJ/mol,Eβ→0 为 106.6 kJ/mol,确定其表观活化能为 106.6￣107.7 kJ/mol。自然凝固工艺制备的 NR 热降解反应的表观活化能高于甲酸凝固工艺制备的 NR 热降解反应的表观活化能。
The kinetics of thermal degradation of the natural rubber (NR) produced with different technologies was studied by use of TG-DTG method under flowing air atmosphere. The activation energy of reaction E at different conversion rate a as well as the apparent activation energy Eα→0 when the conversion rate α was extrapolated to zero were obtained by using the Ozawa's equation. Besides, the activation energy of reaction E at different heating rate as well as the apparent activation energy E b→0 when the b was extrapolated to zero were obtained by using the Coats-Redfern's equation. The result indicates that the apparent activation energy of thermal degradation reaction Eα→0of the NR coagulated with of formic acid in air atmosphere is 101.6 kJ/mol and the E b→0 is 104.5 kJ/mol; therefore, the apparent activation energy of the thermal degradation reaction of the NR coagulated with formic acid was established as 101.6~104.5 kJ/mol. The apparent activation energy of thermal degradation reaction Eα→0 of the NR by natural coagulation is 107.7 kJ/mol and the E b→0 is 106.6 kJ/mol, hence the apparent activation energy of the NR by natural coagulation was established as 106.6~107.7 kJ/mol. The apparent activation energy of thermal degradation reaction of the NR by natural coagulation is higher than that coagulated with the technology of formic acid.
出处
《热带作物学报》
CSCD
2004年第3期10-13,共4页
Chinese Journal of Tropical Crops
