硼酸改性PAN热稳定化行为的研究

Thermal stabilization behavior of PAN modified with boric acid

将硼酸直接加入聚丙烯腈(PAN)聚合液中,制成硼酸改性PAN膜,采用差示扫描量热(DSC)法、傅里叶变换红外光谱(FTIR)、元素分析等手段分析了硼酸对PAN热稳定化过程的影响。结果表明:硼酸改性提高了PAN的热稳定化反应活化能,并使放热峰值温度提高,当硼酸质量分数为2%时,活化能达271.27kJ/mol;硼酸含量越高,对环化反应的抑制作用越强,相对环化率越低;经过相同时间预氧化,改性PAN氧含量相对较低,硼酸改性阻碍了致密氧化层的快速形成,有利于减轻皮芯结构。

A boric acid-modified polyacrylonitrile （PAN） film was prepared by directly adding boric acid into PAN polymerization solution. The effect of boric acid on the thermal stabilization of PAN was analyzed by differential scanning calorimetry （ DSC）, Fourier transform infrared spectrometry （FFIR） and elemental analysis. The results showed that boric acid improved the activation energy of PAN stabilization and raised the exothermic peak temperature; the activation energy reached 271.27 kJ/mol when the mass fraction of boric acid was 2% ; the inhibition effect on the cyclization was stronger and the relative cyclization rate was lower when the boric acid content was higher; the modified PAN had relatively lower oxygen content after pre-oxidation for the same period of time; and boric acid modification hindered the rapid formation of compact oxidation layer and helped to depress the formation of the sheath-core structure.