Medium-density polyethylene blends

Blend Preparations. Blends were made from Uie E/ABP sensitizers and several polyethylenes (E). We used a branched polyethylene, Alathpolyethylene resin, a medium density polyethylene designated Super C, and two hi -denslty polyethylenes, Alathon 7030 and TOHo, GBie E to E/ABP volume ratios ranged from 4A to 22A and laie overall ABP concentrations from... 

Moayad N. Khalaf, Ali H. Al-Mowali, and Georgius A. Adam. (2008) A Rheological Studies of Modified MAPE Medium Density Polyethylene Blends. Malaysian Polymer Journal 3, 5464. 

Medium-density polyethylene is a blend of high-density and low-density polyethylenes. The two components crystallize in separate crystal lamellae with different melting points. 

Medium density polyethylene is fairly similar to and miscible with LDPE [53] and ternary blends of HDPE -I- MDPE -I- LDPE showed some interesting synergism [60]. 

Blends of LLDPE/PP = 50 50, with or without compatibilizing ethylene-propylene copolymer, EPR, were studied by Dumouhn et al. [1984]. In spite of the expected immiscibihty, the blends showed additivity of properties with good superposition of the stress growth functions in shear and elongation, as well as with the zero deformation rate Trouton ratio, Rj, = 1. In earlier work, blends of medium density PE (MDPE) with small quantities of ultra-high molecular weight polyethylene (UHMWPE) were studied in shear and extension. Again, SH and Rj, = 1 were observed. 

Kolesov and Radusch prepared peroxide cross-linked binary and ternary blend SMPs from high density polyethylene and two ethylene-l-octene copolymers with medium and high degrees of branching [47]. The blends were prepared by a melt mixing and subsequently are cross-linked with 2 wt% of liquid peroxide 2,5-dimethyl-2,5-di-(tertbutylperoxy)-hexane at 190°C. The blends showed multiple shape memory behavior that appeared only at consequent stepwise application of convenient programming strains and temperatures. Obviously, that is caused by multiple melting behavior of these blends with many poorly separated peaks. 

In a more recent study, Kelusky, Elston and Murray [11] demonstrated the use of analytical TREF for the analysis of a wide range of polyethylene-based blends. As with the work described above, their analytical TREF system used very small sample and column size, a programmed oven and an IR detector to achieve the necessary reproducibility and resolution. In addition to confirming the effectiveness of TREF for the characterization of blends of LLDPE and LDPE, they showed examples of LDPE/medium density PE blends (Fig. 38) and of ethylene vinyl acetate copolymer/LLDPE blends (Fig. 39). 

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