Shear-induced Precursors of Fibrillar Crystals of Poly(butene-1): A Rheological Study

Mechanisms of Flow-Induced Multistep Structure Evolution in Semicrystalline Polymers Revealed by Molecular Simulations

“…53,125 Chen's group also confirmed the appearance of gel-like precursors in sheared isotactic poly(1-butene). 126,127 Thus, the simulation results presented above can provide reasonable explanations for the formation mechanisms of precursors induced by flow.…”

“…For a long time, it was believed that short chains could not participate in the formation of shish. However, Kimata and co-workers, and Li’s group, determined that short chains indeed join in the development of shish, based on small-angle neutron-scattering method. , To further confirm this and offer insights into why short chains are involved in shish formation, simulation studies were conducted on crystallization of polymer systems containing chains with different lengths. ,,, Figure a depicts that both the crystallinities of the long-chain and short-chain components increase at the early stage of crystallization, validating that the long-chain and short-chain components crystallize during shear-induced crystallization . Further detailed structure analysis of the shish formed during the initial stage of crystallization is presented in Figure b, where small oriented crystallites arranged along the shear direction appear.…”

“…They found that the birefringence increases suddenly during shearing, which means that the precursors of a certain structure are formed . When Kanaya’s group observed the structure of isotactic polystyrene formed in the shear process above its nominal melting point with the polarizing microscope and microbeam X-ray scattering, it was found that some anisotropic strips (precursors) were formed in melts. ,, Winter’s group found that there was a gelation process before crystallization, during which the network structure of precursors was formed. , Chen’s group also confirmed the appearance of gel-like precursors in sheared isotactic poly(1-butene). , Thus, the simulation results presented above can provide reasonable explanations for the formation mechanisms of precursors induced by flow.…”

The Shear‐Accelerated II–I Phase Transition of Isotactic Poly(1‐Butene)

“…[ 21,50 ] Shear can greatly align and stretch the polymer chains, to reduce the energy barrier of nucleation, resulting in a higher density of nuclei, thereby accelerating the phase transition. [ 51 ] In addition, the n increases from 0.41 for the unsheared sample to 0.8 for the sheared one, reflecting the increased growth dimension of Form I with shearing.…”