1. State Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and Engineering Donghua University Shanghai 201620 China
2. Division of Neutron Science Spallation Neutron Source Science Center Dongguan 523803 China
3. Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China
4. School of Polymer Science and Engineering The University of Southern Mississippi Hattiesburg MS 39406‐0001 USA