Morphology diagram of PE gel films in wide range temperature‐strain space: An in situ SAXS and WAXS study

Abstract

Deformation-induced structural evolution of polyethylene (PE) gel films were investigated by in situ synchrotron radiation SAXS and WAXS techniques during stretching at temperatures from 25 C to 110 C. The structural evolutions along tensile strains showed distinct behaviors in the four temperature regions divided by T αI and T αII given by DMA and the onset point of melting measured by DSC, respectively, which was determined by the coupling effects of external stretching field and temperature. Finally, the morphological diagrams of PE gel films on distinct scales including long period of lamellae, crystallinity, and crystal size in 2D temperature-strain space were established, which can give a direct sight of membrane morphologies and act as a map for processing parameters selection.

Inter‐spherulitic/inner‐spherulitic localization of PBSU during crystallization of PVDF in PVDF/PBSU blend

“…SAXS measurements have been performed to assess exclusion behaviors with the help of long periods of PVDF and PBSU. [ 28,29 ] As discussed in our previous work, [ 19 ] the scattering peaks of neat PVDF and PBSU locate at q = 0.53 and 0.74 nm −1 , respectively. In each Lorentz‐corrected SAXS profile of the blend specimens (Figure 2c), there is only one peak locating at q = 0.28 nm −1 (200–141) and 0.35 nm −1 (240–141), corresponding to the long periods of 22.4 nm and 17.9 nm, respectively.…”

Influence of Prereserved Shish Crystals on the Structural Evolution of Ultrahigh-Molecular Weight Polyethylene Films during the Hot Stretching Process

“…The small peak that appears during the long-period decreasing stage of UHMWPE-180 is not the true long period because most of the lamellar crystals are already tilted or broken and gradually rotate away from the stretching direction. It was also found that the rotation of the crystals resulted in the inability to calculate the true long period during the stretching of the PE gel film . In the middle stages of hot stretching, for UHMWPE-135 and UHMWPE-138, the long period slightly decreases, and the distribution of long periods gradually decreases, indicating that both the formation of the prereserved shish-induced shish-kebab crystals and that of the stretch-induced shish-kebab crystals gradually reach a constant.…”

Phase Transitions in Poly(vinylidene fluoride)/Polymethylene-Based Diblock Copolymers and Blends

“…PM crystallizes in an orthorhombic unit cell with parameters a = 0.742 nm, b = 0.495 nm, c = 0.255 nm, and β = 90 • , with a P-D 2h space group [63,64]. The crystallographic planes for these peaks are (110) and (200), respectively [65,66].…”