Strain Hardening and Morphological Evolution in Acid-Containing Polyethylenes via 2D Quantitative Fitting of In Situ X-ray Scattering During Tensile Deformation

Some types of precise polyethylenes, or linear polyethylenes containing precisely periodic functional groups, can exhibit massive strain hardening under tensile deformation. Precise polyethylenes with pendant carboxylic acid groups exhibit strain hardening, while those with imidazolium bromide groups do not. To examine the mechanisms of deformation and evaluate the differences in tensile behavior with respect to morphological evolution, we perform in situ X-ray scattering during tensile deformation. Quantitative evaluation of the 2D fiber patterns show that the carboxylic acid polyethylene undergoes a drastic morphological transition, from a semicrystalline structure to a fibrillar structure, while the morphology of the imidazolium bromide polyethylene simply reorients without undergoing a significant change. This suggests that the fibrillization plays an important role in the strain hardening mechanism.