Elongational rheology of LLDPE / LDPE blends

Abstract

ABSTRACT:The objective of this study is to investigate the effect of low density polyethylene (LDPE) content in linear low density polyethylene (LLDPE) on the crystallinity and strain hardening of LDPE / LLDPE blends. Three different linear low density polyethylenes (LL-1, LL-2 and LL-3) and low density polyethylenes (LD-1, LD-2 and LD-3) were investigated. Eight blends of LL-1 with 10, 20, 30 and 70 wt % of LD-1 and LD-3, respectively, were prepared using a single screw extruder. The elongational behavior of the blends and their constituents were measured at 150°C using an RME rheometer. For the blends of LL-1 with LD-1, the low shear rate viscosity indicated a synergistic effect over the whole range of concentrations, whereas for the blends of LL-1 with LD-3, a different behavior was observed. For the elongational viscosity behavior, no significant differences were observed for the strain hardening of the 10 -30% LDPE blends. Thermal analysis indicated that at concentrations up to 20%, LDPE does not significantly affect the melting and crystallization temperatures of LLDPE blends. In conclusion, the crystallinity and rheological results indicate that 10 -20% LDPE is sufficient to provide improved strain hardening in LLDPE.

Flow instability for binary blends of linear polyethylene and long-chain branched polyethylene

“…= 178.5(0.9644) Pe/ w (7) Although this empirical relation has no theoretical background, it has been proved that numerous data follow Eq. (7) [57].…”

“…They found that zero-shear viscosity of the blends exhibits positive deviation from the logadditive rule. Later, Ajji et al [7] found that LDPE/LLDPE blends containing 10-20 wt% of LDPE show marked strain-hardening behavior in elongational viscosity. Wagner et al [8] also demonstrated that the strain-hardening behavior for LDPE/LLDPE is more pronounced than that for pure LDPE.…”

Recent Advances in Preparation of Porous Polymeric Membranes by Unique Techniques and Mitigation of Fouling through Surface Modification

“…Compared to PP, HDPE shows greater deformity and the strain hardening at the lower slope. In the elastic region, deformation force is not sufficient to generate pores while as in plastic zone, lamellae, an increased elongation broadens pore size . Zuo et al .…”

Branching degree and rheological response correlation in peroxide-modified linear low-density polyethylene

“…They are also widely being used in the film industry to enhance bubble stability during tubular film extrusion taking advantage of the superior physical properties of LLDPE. However, in spite of these efforts, a review of previous investigations to understand various aspects of polyolefin blends, such as miscibility and phase separation, processability and strain hardening, crystallization, and mechanical behavior reveals the complexity of the problem and highlights the need for further research …”

“…However, in spite of these efforts, a review of previous investigations to understand various aspects of polyolefin blends, such as miscibility and phase separation, processability and strain hardening, crystallization, and mechanical behavior reveals the complexity of the problem and highlights the need for further research. [3][4][5][6][7][8][9][10] The modification of polyolefins has been intensely developed in the last decade because it is a relatively easy and economical method of increasing the range of application of mass-produced materials such as polyethylene (PE) and polypropylene. Moreover, for improving the processability of LLDPE, several new technologies have been developed in film-blowing process, such as spiral dies, dual lip air ring technology, lower pressure, grooved barrel feed sections, and high efficiency barrier screws.…”