Preparation of High‐Performance Linear Low‐Density Polyethylene/Polypropylene Alloy by Dual‐Speed Non‐Twin Screw Extruder

ABSTRACT Linear low‐density polyethylene (LLDPE) and polypropylene (PP), as two important general‐purpose thermoplastic polymers, are widely used in many fields such as packaging, construction, and automobiles. Blending two or more polymers is an effective way to develop new materials with excellent comprehensive properties. However, LLDPE/PP alloys prepared by twin‐screw extruder (TSE) often have problems of uneven dispersion of the dispersed phase and severe phase separation. These issues restrict the performance and popularization of LLDPE/PP alloys. This study innovatively adopts a novel dual‐speed non‐twin screw extruder (NTSE) to prepare LLDPE/PP alloys with excellent comprehensive properties under the condition of a relatively low compatibilizer addition amount (4 wt%). Comparative studies have found that, compared with TSE, the LLDPE/PP alloys prepared by NTSE possessed a smaller average particle size of the dispersed phase, a more uniform particle size distribution, and improved compatibility between the two phases. The improvement of the microstructure directly leads to the enhancement of the macroscopic properties of the material. Compared with TSE, when the compatibilizer addition amount was 4 wt%, the tensile strength of the alloy prepared by NTSE increased by 13.5%, the elongation at break increased by 13.9%, and the puncture resistance increased by 8.8%, even exceeding that of pure LLDPE. Moreover, with 4 wt% compatibilizer addition, the haze of LLDPE/PP prepared by NTSE was 10.4%, which was 62.2% lower than that of 27.5% prepared by TSE. This characteristic has important application value in the field of food packaging that requires high transparency. This study provides a practical technical solution for preparing new high‐performance polymer blends. This technical solution can also be applied to plastic recycling and is easy to realize industrial promotion.