Investigation of Crystallization, Morphology, and Mechanical Properties of Polypropylene/Polypropylene-Polyethylene Block Copolymer Blends

Abstract

Polyethylene (PE)-based elastomers are the ideal choice for enhancing the compatibility of polypropylene/polyethylene (PP/PE) blends and improving the mechanical properties of PP-based materials. However, the issue of blend systems lies in the interplay between the crystallization processes. Therefore, we investigated the crystallization behavior during the cooling process of a new generation of PP/PE block copolymers (PP-b-PE) and random polypropylene (PPR, a copolymer of propylene and a small amount of ethylene or an alpha-olefin) blends using in-situ X-ray diffraction/scattering and differential scanning calorimetry (DSC) techniques. We also conducted mechanical performance tests on PPR/PP-b-PE blends at room temperature and low temperature (−5 °C). The results indicate that during the cooling process, the PP phase of PP-b-PE will follow the PPR to crystallize in advance and form a eutectic mixture, thereby enhancing the compatibility of PP/PE. Moreover, the PPR/PP-b-PE blend will form stable β-(300) crystals with excellent mechanical properties. Due to the improved compatibility of PP/PE with PP-b-PE, PE crystals are dispersed within PP crystals, providing bonding that improves the toughness of PPR under the low stiffness failure conditions of PPR/PP-b-PE blends, thereby enhancing their impact performance at low and room temperatures. This research has great significance for both recycling waste plastics and enhancing the low-temperature toughness of PPR.

Scalable, Waterproof, Breathable, and Flexible Polyolefin-Elastomer/Polyethylene Glycol@Zinc Oxide Microfibrous Fabrics for Daytime Radiative Cooling Clothing

“…In addition, a small heat dissipation peak appeared at 154.8 °C, indicating that the PP/POE@ZnO polymer exhibited a small microphase separation. 25 By comparison, the cold crystallization peak in the cooling curves (T c ) decreased from 114 to 102 °C. The DSC and TG curves of POE and PP are displayed in Figures S1 and S2, respectively.…”

“…Moreover, the melting peak ( T m ) increased from 161.4 to 164.9 °C with the ZnO mass ratio increasing from 0% to 4%. In addition, a small heat dissipation peak appeared at 154.8 °C, indicating that the PP/POE@ZnO polymer exhibited a small microphase separation . By comparison, the cold crystallization peak in the cooling curves ( T c ) decreased from 114 to 102 °C.…”