聚合物结晶成核剂作用的表征方法的比较和研究

用聚合物的等速降温过程的结晶温度，等温结晶过程的半结晶时间（ｔ１／２）或结晶速度常数（Ｋ），结晶过程的晶核密度或球晶尺寸大小和聚合物结晶成核界面自由能（σσｅ或σｅ）大小等方法描述了碳酸钙、对苯二甲酸、苯甲酸钠对聚丙烯成核结晶过程的影响．通过对不同方法的比较，结果表明不同方法是从不同角度来反映助剂对聚合物成核结晶过程的影响，聚合物结晶温度的高低和等温结晶过程的半结晶时间或结晶速度常数是描述聚合物整体结晶速度的参数；而聚合物结晶过程中晶核密度或结晶完了时聚合物球晶尺寸，和聚合物结晶成核界面自由能大小与聚合物的成核难易程度直接相关，是判断聚合物结晶成核速度的方法．但不同方法之间存在一定的相关性，所以用不同方法测定的结果之间有较好的可比性，可根据具体条件选用一种方法．多种方法的配合使用可以较全面的了解成核剂的作用．

COMPARISON OF METHODS FOR CHASRCTERIZING THE EFFECTS OF NUCLEATING AGENTS ON THE PROCESS OF POLYMER CRYSTALLIZATION

The influence of nucleating agent on the process of nucleation and crystallization of isotactic polypropylene from melt state was studied by different characterization methods including the measurements of the crystallization temperature in a non isothermal colling process, halftime and velocity constant in an isothermal crystallization process, the density of nuclei or the size of spherulites and the specific surface free energy for nucleus formation during crystallization. The nucleating agents used were calcium carbonate, sodium benzoate and terephthalic acid. It was found that all the three nucleating agents may have their influence on the crystallization of polypropylene. The results obtained by using different characterization methods were consistent with each other. It implies that there are some correlations between the parameters used for characterization in different methods. So it is feasible to use any one of these methods to evaluate the effect of additives on polymer crystallization in an applied research. However, the use of various characterization techniques may give you a comprehensive usderstanding of the effect of nucleating agents on the crystallization process of polymers.