Thermal and rheological properties of mLLDPE/LDPE blends

Abstract

The thermal and rheological properties of two types of metallocene-catalyzed linear low-density PEs (mLL-DPEs) and two LDPEs, as well as their blends, were studied using differential scanning calorimeter (DSC) measurements and rheometry. The DSC results showed that the mLLDPE-1 based on the hexene comonomer is immiscible with both LDPEs in crystalline states, whereas the mLLDPE-2 based on the octene comonomer is miscible with the LDPEs. This suggests that increasing the length of short chains in mLLDPEs can promote the miscibility of mLLDPE/ LDPE blends. The linear viscoelastic properties confirmed the immiscibility of the mLLDPE-1 with the LDPEs in the molten state, and the miscibility of mLL-DPE-2 with LDPEs. In addition, the Palierne [1] emulsion model provided good predictions of the linear viscoelastic data for both miscible and immiscible PE blends. However, as expected, the low-frequency data showed a clear influence of the interfacial tension on the elastic modulus of the blends for the immiscible blends. POLYM. ENG. SCI., 45:1254 -1264, 2005. © 2005 Society of Plastics Engineers

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

“…[1][2][3][4][5][6][7] However, this enhancement of processing and properties is dictated by phase homogeneity or heterogeneity of these blends in the melt and solid state. A large number of studies utilizing different techniques were devoted to investigate the phase morphology and characterization of polyolefin blends.…”

“…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][12][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.…”

“…33,34 Mechanical characterization of polyolefin blends has also been a subject of interest. 2,[5][6][7][20][21][22][23][30][31][32] Molecular parameters like branch content (BC), branch type, composition distribution, molecular weight (M w ) and molecular weight distribution (MWD) were found to be the key factors affecting the miscibility of polyolefin blends. Hill 9 using transmission electron spectroscopy (TEM) found that M w of linear HDPE had little influence on its miscibility with branched PEs.…”

“…Recently, Fang et al 2 investigated melt miscibility of m-LLDPE/LDPE blends. Two sets of blends were prepared and compared to study the influence of short chain branching (SCB) and M w .…”

Thermal, Mechanical and Rheological Properties of Low Density/Linear Low Density Polyethylene Blend for Packing Application

“…They reported that the complex behavior of these blends can be understood by assuming the existence of two phases; one phase composed of the highly branched low Mw chains of both polyethylenes, and a second phase composed of the high Mw chains (mostly linear) of both polyethylenes. Differential scanning calorimetry (DSC) thermograms of LLDPE/LDPE blends reported by Fang [5] supported the existence of a third phase composed of chains from the two polyethylenes that have the ability to cocrystallize; additionally, enhancement in the crystallization behavior of BPE blended with linear polyethylene (LPE) was explained in terms of co-crystallization due to the incorporation of the linear segments of BPE into rich LPE lamellae and the segregation of the most branched chains.…”