Morphology of Blends of Linear and Short-Chain Branched Polyethylenes in the Solid State by Small-Angle Neutron and X-ray Scattering, Differential Scanning Calorimetry, and Transmission Electron Microscopy

Abstract

Differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and small-angle neutron and X-ray scattering (SANS and SAXS, respectively) have been used to investigate the solid-state morphology of blends of linear (high-density) and model short-chain branched (linear-low-density) polyethylenes (HDPE/LLDPE). SANS indicates that the mixtures are homogeneous in the melt for all compositions when the ethyl branch content in the copolymer is low (i.e., <4 branches/100 backbone carbon atoms for a molecular weight of M w ∼ 105). However, due to the structural and melting point differences between HDPE and LLDPE, the components may phase segregate in the solid state. The degree of separation is therefore controlled by the crystallization kinetics. DSC, TEM, SAXS, and SANS experiments have been used to investigate the solid-state morphology as a function of component composition, the thermal history, and the rate of cooling. It is shown that the combination of scattering, microscopy, and calorimetric techniques can provide detailed insight into the compositions of the various populations of the lamellar crystals and the amorphous regions that surround them.

(nBuCp)2ZrCl2‐catalyzed ethylene‐4M1P copolymerization: Copolymer backbone structure, melt behavior, and crystallization

“…The experimental procedure reported in the literature was followed. [38][39][40] The data were acquired for each cycle and handled using the TA explorer software. The measured X c was subsequently used to calculate the polymer material density q polym , following the rule of additivity of volumes of polyethylene amorphous and crystalline phases:…”

Melt Miscibility and Mechanical Properties of Metallocene LLDPE blends with HDPE: Influence of Mw of LLDPE

“…Earlier, BC and composition distribution were reported to influence solid state compatibility of PE blends. [10][11][12][14][15][16][17][18][19][21][22][23] Since the BC for m-EH1 and m-EH2 are similar (BC ¼ 18, 20.7 branches/1000 C) and are both produced by metallocene catalyst, similarity in solid state morphology suggest no influence of M w on the compatibility of m-EH/HDPE blends. Figure 7a shows the second heating scans for high BC low M w m-EB1/HDPE blends and the pure resins.…”

“…A large number of studies utilizing different techniques were devoted to investigate the phase morphology and characterization of polyolefin blends. These techniques include transmission electron spectroscopy, [8][9][10][11] small angle neutron scattering, 11-13 differential scanning calorimetry, 2,5,11,[14][15][16][17][18][19][20][21][22][23] rheology, 3,4,6,7,[16][17][18][24][25][26][27][28][29][30] X-ray diffraction 11,14,31 and more recently thermal fractionation techniques. 33,34 Mechanical characterization of polyolefin blends has also been a subject of interest.…”

Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

“…The instrument was calibrated using indium. The experimental procedure reported in the literature was followed [23,24]. The data were acquired for each cycle and handled using the TA explorer software.…”