Versatile Polypropylene Copolymers from a Pilot-Scale Spheripol II Process

Abstract

Polypropylene (PP) is one of the most widely used polymers. In this paper, three types of PPs including random PP, impact PP, and impact PP with high clarity, were prepared through a 75 kg/h pilot-scale Spheripol II process. The three produced PPs were produced by the selection or combination the two loops and gas phase reactor and controlling the comonomer and hydrogen concentrations. The three prepared PPs then were pelleted with the clarified nucleating agent NX 8000 and tested for mechanical, thermal, and optical properties. Their molecular structures and rubber phase size were also investigated by GPC, 13C NMR, temperature rising elution fractionation (TREF), XRD, SEM analysis, etc. The results showed that the random PP (PP-1) and the impact PP with high clarity (PP-3) obtained excellent optical transparency with a haze of 12.5% and 13.5% due to their small rubber phase size (roughly ≤ 100 nm), while the impact PP (PP-2) obtained bad transparency with a haze of 98.8% due to the large rubber phase size (about 1 μm) caused by the poor thermal compatibility with the PP matrix. The rubber phase content and ethylene/propylene sequence distributions of the three PPs varied much and resulted in different impact strengths and stiffness properties. PP-2 had a high impact strength of 14.5 kJ/m2 due to the rubber phase generated in the gas phase reactor. Except for the optical transparency, PP-3 gained stiffness and toughness, with 914 MPa of flexural modulus and 25.1 kJ/m2 of impact strength due to the unique molecular structure of its rubber phase.

Porous Organic Polymers-Supported Zeigler-Natta Catalysts for Preparing Highly Isotactic Polypropylene with Broad Molecular Weight Distribution

“…Differential scanning calorimetry (DSC) analyses were tested on a DSC 214 instrument (Netzsch, Selb, Germany). Temperature rising elution fractionation (TREF) was carried out on a Polymer Char model 200+ from Spain using TCB as solvent [ 6 ]. X-ray photoelectron spectroscopy (XPS) characterization was conducted on an ESCA Lab 250 spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) with Al Kα radiation at 1486.6 eV [ 34 ].…”

“…Since the discovery of the Ziegler–Natta catalyst more than 60 years ago, the consumption of polyolefins has been growing with catalyst technology and polymerization process innovations [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. In 2021, the global consumption of polyolefins had arrived at approximately 200 million tons, and polypropylene (PP), typically isotacitc PP, is widely used in various walks of life, such as automobiles, packaging, household, medical and facilities industries [ 8 , 9 ], with predicted global demand of above 75 million tons in 2022.…”

Machine learning for revealing the relationship between the process–structure–properties of polypropylene in-reactor alloys

“…This technique involves the homo-polymerization of propylene to produce PP, followed by copolymerization of propylene and ethylene, resulting in the formation of a copolymer (ethylene–propylene rubber). 5 This approach circumvents the challenges associated with achieving effective mixing on submicron scales between the rubber phase and PP phase using traditional mixing processes. 6 However, this advancement introduces new complexities as the structure of the in-reactor alloy becomes more complicated 7 due to copolymerization reactions, yielding products such as block copolymers and random copolymers.…”