松脂的氧化动力学研究

Oxidation reaction kinetics of pine gum

为研究松脂的氧化反应动力学,采用紫外分光光度法定量测定固态枞酸在聚乙烯膜上的吸光度变化,求出松脂参与氧化反应的反应量,进而研究松脂氧化反应动力学。实验结果表明,松脂的热氧化和光氧化反应动力学均呈现表观一级反应。热氧化反应温度为35、40、45℃时的表观速率常数分别为3.000×10-4、5.000×10-4、1.100×10-3 min-1,反应活化能Ea为105.8 kJ/mol。254 nm紫外灯辐照下,温度为35、40、45℃时,光强度与表观速率常数的关系分别k=1.162×10-4I+2.626×10-4、k=1.248×10-4I+4.588×10-4、k=1.298×10-4I+0.001 1。

The absorbency of abietic acid on the polyethylene film was determined by UV spectro- photometry, and the oxidation degree of pine gum was investigated. Oxidation reaction kinetics of pine gum was studied. The experimental results indicates that the thermal oxidation and photo-oxidation reaction are pseudo first order reaction. When the thermal oxidation reaction temperatures are 35℃, 40 ℃ and 45 ℃, the apparent reaction rate constants of pine gum are 3. 000 × 10-4 min-1, 5. 000 × 10-4 rain-1 and 1. 100 × 10 -3 min-1, respectively. The activation energy is 105.8 kJ/mol. Under 254 nm ultraviolet light irradiation, when oxidation reaction temperatures are 35 ℃, 40 ℃ and 45 ℃, respectively, the relationships between the rate constant（k） and the light intensity （I） are k = 1. 162 × 10 -4I ＋ 2. 626 × 10 -4, k = 1. 248 × 10 -4I ＋ 4. 588 × 10 -4 and k = 1. 298 × 10 -4I ＋ 0. 001 1, respectively.