Development of industrial film from HDPE/MLLDPE blend

Abstract

High density polyethylene (HDPE)/metallocene linear low density polyethylene (MLLDPE) blend and high density polyethylene/Ziegler-Natta linear low density polyethylene (Z-NLLDPE) blend were prepared by melt mixing in a single screw extruder. The composition of the blends had been varied, 0-40% by weight of MLLDPE or Z-NLLDPE and the blown films with 25 micron thickness of each blend were made. All these films were subject to the mechanical testing, i.e., tensile strength, elongation at break, film impact strength and seal strength according to the corresponding ASTM methods. The results reveal that the mechanical properties of HDPE/MLLDPE film are superior than HDPE/Z-NLLDPE film. The clarity of the films had also been determined by using densitometer. Both types of the film had about the same clarity. The HDPE/MLLDPE films with 15 micron thickness had also been prepared and subject to the mechanical testing. Their mechanical properties are approximate to, with some properties slightly better than, HDPE/Z-NLLDPE films of the corresponding compositions but with 25 micron thickness. The morphology of the blends were examined by dynamic mechanical thermal analysis (DMA) and differential scanning calorimeter (DSC). The results revealed that HDPE/MLLDPE blends were miscible in the crystalline phase but immiscible in the amorphous phase.