对甲基苯甲酸镧铈的合成及对天然橡胶的硫化促进作用

Synthesis of lanthanum cerium p-methylbenzoate and its acceleration effect on vulcanization of natural rubber

以对甲基苯甲酸为配体、稀土镧铈为中心体合成了对甲基苯甲酸镧铈,通过傅里叶变换红外光谱、热分析及元素分析对其进行了表征。将其作为硫化促进剂添加到天然橡胶中,测定了添加量不同时胶料的硫化曲线和硫化参数,进行了溶胀实验,并根据硫化动力学模型对硫化曲线进行了非线性拟合,求得了硫化各阶段的活化能。结果表明,对甲基苯甲酸镧铈的加入使得天然橡胶的焦烧时间延长、最大转矩增大,热硫化阶段的硫化速率指数由未添加时的119提高至添加0.6份(质量)时的147,溶胀指数从4.8469降至3.9719,交联密度由1.14×10^(-4) mol/cm^(3)提高至1.89×10^(-4) mol/cm^(3),多硫键生成阶段、多硫键生成单硫键和双硫键阶段及多硫键断裂生成改性主链阶段的活化能分别为67.85,101.00,126.00 kJ/mol,均低于相应的未添加体系,说明对甲基苯甲酸镧铈发挥了促进天然橡胶硫化的作用。

Lanthanum cerium p-methylbenzoate was synthesized with p-methylbenzoic acid as ligand and rare-earth lanthanide cerium as centrosome,and was characterized by Fourier transform infrared spectroscopy,thermal analysis and elemental analysis.It was added to natural rubber as a vulcanization accelerators,and the vulcanization curve and vulcanization parameters of natural rubber with different amount of accelerators were measured,and the swelling experiments were carried out.The nonlinear fitting of vulcanization curve was carried out accor-ding to the vulcanization kinetics model,and the activation energy of each vulcanization stage was obtained.The results showed that the addition of lanthanum cerium p-methylbenzoate prolonged the scorch time and increased the maximum torque of natural rubber.The vulcanization rate index of hot vulcanization stage increased from 119 when it was not added to 147 when 0.6 phr(mass)was added,swelling index decreased from 4.8469 to 3.9719,and crosslinking density increased from 1.14×10^(-4) mol/cm^(3) to 1.89×10^(-4) mol/cm^(3).The activation energies of formation stage of polysulfide bond,monosulfide bond and disulfide bond,and modified main chain were 67.85,101.00,126.00 kJ/mol,respectively,which were lower than those of the corresponding systems without lanthanum cerium p-methylbenzoate,indicating that lanthanum cerium p-methylbenzoate played a role in promoting vulcanization of natural rubber.