中文摘要：

介绍了近年发展起来的几种结晶分级技术及其在支化聚乙烯结构表征及性能研究方面的应用。利用升温淋洗分级技术（TREF），可根据结晶特性的不同将高分子分离成多个分布较窄的级份，通过分别表征各级份的链结构，从而可获得高分子链结构方面较为准确的信息。基于差示扫描量热技术（DSC）发展起来的两类热分级技术，主要包括逐步结晶热分级（SC）和连续自成核退火分级（SSA）技术，虽然不能从物理上对高分子进行分级，但通过选择适当的操作参数，也能得到一系列与升温淋洗分级实验类似的链结构信息，并且具有设备简单、操作方便、样品用量少、耗时短等优点。本文结合我们自己的工作，对各种分级技术的原理、实验操作及应用进行了系统综述。并展望了结晶分级技术发展的某些可能趋势。

英文摘要：

Several kinds of important crystal fractionation techniques as well as their application in the examination and characterization of short-chain branched polyethylene were introduced. Temperature rising elution fractionation （TREF） could be used to separate polymers into fractions according to the difference of their crystallization abilities and obtain structure information of semi-crystalline polymers by further characterization of these fractions. DSC based thermal fractionation techniques, including step crystallization （SC） and successive self-nucleation and annealing （SSA） thermal analysis, might be also used to investigate the polymer structure information similar to TREF, which are time-saving and cost-saving in comparison with TREF. Principles, operations and applications of these fractionation techniques were reviewed and some possible topics of crystal fractionation techniques were also discussed.