尼龙1218的等温及非等温结晶动力学研究

采用示差扫描量热计DSC考察了一种新型长烷基链偶偶尼龙 尼龙 12 18 自熔体的结晶过程 ,分别利用Avrami方程和Ozawa方程对等温及非等温结晶动力学进行了描述与研究 ,计算了相关的结晶动力学参数 ,得出相应的结晶机理 .最后计算了等温结晶活化能和非等温结晶活化能 ,依此得到烷基链段长度与尼龙结晶过程有密切关系

INVESTIGATION ON CRYSTALLIZATION KINETICS OF NYLON 1218

The crystallization kinetics has been investigated by differential scanning calorimetry for polyamide 1218,a novel even-even nylon with long allkyl segments.Avrami equation and Ozawa approach have been adopted to study both the isothermal and non-isothermal processes.It is shown that the Avrami equation is applicable for isothermal crystallization very well,and the calculated Avrami index n is 3,which demonstrates that the crystallization of nylon 1218 is growing with global tridimensional crystals in this situation.As for the non-iosthermal crystallization,the Ozawa methed only fits at fast cooling rates,and the calculated Ozawa index m is 4,which indicates nylon 1218,in non-isothermal terms,may crytallize by a way of homogeneous nucleation and tridimensional growth.In addition,the activation energies for isothermal and non-isothermal crystallization have been determined according to the Arrhenius and Kissenger methods,respectively.A comparison of the activation energy values of nylon 1218 with those of nylon 1012 and nylon 11 indicates that at same conditions an increase of the alkyl segment length in the nylon molecules is beneficial to their crystallization,and the even-even nylons with long alkyl segments are easier to crystallize than the single nylons.