脒端基对聚丙烯腈原丝氧碳化行为的影响

Effect of Amidine End Group on Preoxidation and Carbonation of Polyacrylonitrile Precursor

以偶氮二异丁脒盐酸盐(AIBA)、偶氮二异丁腈(AIBN)为引发剂,分别制备了具有不同端基结构的丙烯腈与衣康酸共聚物PAN-AIBA和PAN-AIBN,采用湿法纺丝技术制备PAN原丝。采用两种梯度升温方式对PAN原丝进行热稳定化处理,对优选的预氧化纤维进行高温碳化制得碳纤维。采用多种手段表征纤维结构与组成的变化规律。结果表明,脒端基可提高PAN预氧纤维的相对环化率,使其氧含量和体密度平稳增长,因此有利于预氧化纤维的结构调控。PAN-AIBA基碳纤维的皮芯结构差异小于PAN-AIBN基碳纤维,与其相对温和的热稳定化行为相符。

Copolymers of acrylonitrile and itaconic acid with different end group were prepared using azobis（2-methylpropionamidine）dihydrochloride（AIBA）and azobis（isobutyronitrile）（AIBN）as the initiator,respectively.PAN precursors were fabricated by wet-spinning method.Two sets of gradient heating processes were adopted to stabilize each sample before the well-chosen preoxidized samples were finally carbonizated.Evolutions of fiber structure and composition were traced by 1 H-NMR,DSC,EA.It showed that the relative cyclization index,oxygen content and bulk density of the stabilized PAN fiber increase by introducing amidine as the end group of the polymer.The oxygen content and bulk density of the pre-oxided PAN-AIBA fiber increase more evenly than that of PAN-AIBN,which are favorable for evolution of the preoxidation structure of PAN precursor and process control of thermal stabliziation.Compared with PANAIBN based carbon fiber,the reduction of sheath-core structure of the PAN-AIBA based carbon fiber was observed,consistenting with PAN-AIBA relatively mild thermal stablization behavior.