A disentangled state using TiCl4/MgCl2 catalyst: a case study of polyethylene

• Published in: Iranian polymer journal Vol. 27; no. 9; pp. 701 - 708
• Main Authors: Heidari, Amin, Zarghami, Hamid, Talebi, Saeid, Rezaei, Mostafa
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-09-2018; Springer Nature B.V
• Subjects: Catalysis; Catalysts; Ceramics; Chemical synthesis; Chemistry; Chemistry and Materials Science; Composites; Diffraction patterns; Drawability; Entanglement; Glass; Hexagonal phase; Magnesium chloride; Melting points; Molecular weight distribution; Morphology; Natural Materials; Original Research; Polyethylene; Polyethylenes; Polymer Sciences; Polymerization; Polymers; Rheological properties; Titanium chlorides; X-ray diffraction; Mechanical properties; Ziegler–Natta catalyst; UHMWPE; Solid-state drawability; Disentangled state
• ISSN: 1026-1265; 1735-5265
• DOI: 10.1007/s13726-018-0648-z

Fully entangled morphology which is usually expected for polyethylene produced using Ziegler–Natta (ZN) catalyst is due to the presence of active sites crowded on catalyst’s support surface as well as within its volume. In this research, the feasibility of producing disentangled, more precisely less entangled, polyethylene using a heterogeneous ZN catalyst supported on magnesium chloride, TiCl
4
/MgCl
2
, is introduced. Polymerization was carried out at rather low temperature and pressure, and the nascent polymer was characterized to investigate its entanglement state. The rheological measurements, at small amplitude oscillating in the time sweep mode, exhibited a rather good modulus build-up, demonstrating the nascent polymer in its dis(less)-entangled state. Tape and film samples were prepared from the synthesized polyethylene below its melting point to keep the morphology untapped. The solid-state drawability test was performed on the samples at 100 °C showing its improved drawability. Thus, it could be concluded that the polyethylene synthesized at rather low temperature of 0 °C and longer polymerization time was in disentangled state. Furthermore, a rheometrical analysis in frequency mode was used to estimate the molecular weight and molecular weight distribution of the synthesized polyethylene qualitatively. From X-ray diffraction patterns the existence of a small amount of hexagonal phase in the nascent polymer could be detected, which may be due to the formation of extended chains during polymerization.