Influence of Composition Distribution and Branch Content on the Miscibility of m-LLDPE and HDPE Blends:  Rheological Investigation

Abstract

The miscibility of metallocene linear low-density polyethylene (m-LLDPE) and Ziegler−Natta LLDPE (ZN-LLDPE) with linear high-density polyethylene (HDPE) was studied. The influences of composition distribution (CD) and branch content (BC) on the miscibility of m-LLDPE and ZN-LLDPE with HDPE were investigated with rheological methods. The m-LLDPEs (BC = 13.2 CH3/1000 C) and ZN-LLDPE (BC = 14.5 CH3/1000 C) of similar molecular weights were paired to study one molecular variable at a time. Melt blending was carried out in a Haake PolyDrive at 190 °C in the presence of 1000 ppm of antioxidants. Dynamic and steady shear measurements were performed in a Rheometrics ARES at 190 °C. The miscibilities of blends were revealed by the dependence of their ηo, η‘, N 1 and G‘ on blend composition and from predictions of rheological models. The CD was found to have no effect on the miscibility of low-BC ZN-LLDPE and m-LLDPE blends with linear HDPE, and both blends were miscible at all compositions. Increasing the branch content (BC = 42.0 CH3/1000 C) resulted in an increased immiscibility of m-LLDPE-rich blends with linear HDPE. The rheology of immiscible blends suggests a layered morphology and agreement with Bousmina−Palierne−Utracki's and Lin's models was obtained with slip parameters k = 2.85 × 10-5 and λ = 0.72, respectively.

Caracterização estrutural de nanocompósitos de blendas HDPE/LLDPE e OMMT obtidos por diferentes sequências de mistura

“…Através desta análise foi possível observar a presença de uma única transição vítrea para a blenda HDPE/LLDPE, sendo a temperatura intermediária entre as temperaturas das transições vítreas dos materiais puros, apresentados na Tabela 1. Além disso, o valor da T g obtido experimentalmente (-115,3 °C) está em concordância com o valor de T g calculado através da Equação de Fox [25] (-115,8 °C), sugerindo que a blenda polimérica possivelmente seja miscível.…”

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

“…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.…”

“…Recently, the authors have extensively studied the influence of molecular parameters on the miscibility of different polyethylenes [21][22][23][24][25][26][27] using rheological techniques. M w of m-LLDPE 24 and ZN-LLDPE 28 was found to have a strong influence on its miscibility with LDPE. Low M w m-LLDPE (67 kg/mol) blends with LDPE were miscible at all compositions while the high M w m-LLDPE (108 kg/ mol) blends showed partial miscibility at high LLDPE content and immiscibility at low LLDPE content with the same LDPE.…”

Correlation between rheological and mechanical properties of black PE100 compounds – Effect of carbon black masterbatch

“…Figure 3a shows steady shear rheological properties of black masterbatch samples in comparison with NPE100 sample. It is well accepted that for melt miscibility and good mixing of polymeric materials, their rheological properties should be comparable [24,25]. In other words, for better rheological miscibility, the flowability of masterbatch, containing 35-40 wt% carbon black, should be comparable with the polyethylene host resin.…”