Molecular weight fractionation in tubular flow-induced crystallization of polyethylene

Synthesis of high molecular weight polyethylene using FI catalyst

A FI Zr-based catalyst of bis[N-(3,5-dicumylsalicylidene)-2′,6′­diisopropylanilinato]zirconium(IV) dichloride was prepared and used for polymerization of ethylene. The effects of reaction conditions on the polymerization were examined in detail. The increase in ethylene pressure and rise in polymerization temperature up to 35 oC were favorable for catalyst/MAO to raise the catalytic activity as...

Continuous Crystallization of Proteins in a Tubular Plug-Flow Crystallizer

Protein crystals have many important applications in many fields, including pharmaceutics. Being more stable than other formulations, and having a high degree of purity and bioavailability, they are especially promising in the area of drug delivery. In this contribution, the development of a continuously operated tubular crystallizer for the production of protein crystals has been described. Us...

Wear of Ultra High Molecular Weight Polyethylene

The non-equilibrium phase diagrams of flow-induced crystallization and melting of polyethylene

Combining extensional rheology with in-situ synchrotron ultrafast x-ray scattering, we studied flow-induced phase behaviors of polyethylene (PE) in a wide temperature range up to 240 °C. Non-equilibrium phase diagrams of crystallization and melting under flow conditions are constructed in stress-temperature space, composing of melt, non-crystalline δ, hexagonal and orthorhombic phases. The non-...

Crystallization-Based Fractionation Techniques

The vast majority of commercial polyolefins are semi-crystalline materials. Depending on the chemical composition and tacticity, their melting temperatures range from ambient to temperatures exceeding 160 C. Polyolefins form various crystalline structures that can be investigated with microscopic, spectroscopic and scattering techniques. When a semi-crystalline polyolefin is dissolved in a solv...