Patchanee Chammingkwan

MgO/MgCl2/TiCl4 Core–Shell Catalyst for Establishing Structure–Performance Relationship in Ziegler–Natta Olefin Polymerization

AbstractRecently we successfully established the first structure–performance relationships between the catalyst surface area and propylene polymerization activity using novel MgO/MgCl2/TiCl4 core–shell catalysts with non-porous and non-fragmentable features. In the present paper, we have addressed the physical and chemical natures of these novel model catalysts in comparison with typical Ziegler–Natta catalysts, by means of comprehensive characterization and analyses. It was clarified that the MgO/MgCl2/TiCl4 core–shell catalysts offer an ideal and powerful tool to address relationships between the support architectures and polymerization performance, which had been long un-clarified. Graphical AbstractUnique structure of MgO/MgCl2/TiCl4 core–shell catalysts but yet identical surface chemistry with typical Ziegler–Natta catalyst offers an ideal and powerful tool to address relationships between the support architectures and polymerization performance.

Enhancement in Mechanical and Electrical Properties of Polypropylene Using Graphene Oxide Grafted with End-Functionalized Polypropylene

Terminally hydroxylated polypropylene (PP) synthesized by a chain transfer method was grafted to graphene oxide (GO) at the chain end. Thus obtained PP-modified GO (PP-GO) was melt mixed with PP without the use of a compatibilizer to prepare PP/GO nanocomposites. Mechanical and electrical properties of the resultant nanocomposites and reference samples that contained graphite nanoplatelets, partially reduced GO, or fully reduced GO were examined. The best improvement in the tensile strength was obtained using PP-GO at 1.0 wt %. The inclusion of PP-GO also led to the highest electrical conductivity, in spite of the incomplete reduction. These observations pointed out that terminally hydroxylated PP covalently grafted to GO prevented GO layers from re-stacking and agglomeration during melt mixing, affording improved dispersion as well as stronger interfacial bonding between the matrix and GO.

Well-Defined Polypropylene/Polypropylene-Grafted Silica Nanocomposites: Roles of Number and Molecular Weight of Grafted Chains on Mechanistic Reinforcement

Grafting terminally functionalized polypropylene (PP) to nanofillers provides well-defined PP-based nanocomposites plausibly featured with a physical cross-linkage structure. In this paper, a series of PP-grafted silica nanoparticles (PP-g-SiO2) were synthesized by varying the number of grafted chains per silica particle, and influences of the number and the molecular weight of grafted chains were studied on physical properties of PP/PP-g-SiO2 nanocomposites. We found that only 20–30 chain/particle was sufficient to exploit benefits of the PP grafting for the nanoparticle dispersion, the nucleation, and the Young’s modulus. Meanwhile, the yield strength was sensitive to both of the number and the molecular weight of grafted PP: Grafting longer chains at a higher density led to greater reinforcement.

High-Throughput Synthesis of Support Materials for Olefin Polymerization Catalyst

Rational catalyst design necessitates fundamental knowledge on the structure-performance relationship, while the synthetic throughput for heterogeneous Ziegler-Natta olefin polymerization catalysts has long prevented the acquisition of a statistical database. In this contribution, an in-house reactor system was developed to realize the parallel synthesis of support materials for Ziegler-Natta catalysts for the first time. The developed system enabled parallel synthesis of 24 magnesium ethoxide samples with excellent reproducibility and morphological control comparable to a conventional experiment. Our demonstration revealed that the generation of diverse particle characteristics could be achieved through the addition of a third component as a structural modulator, in which the in-house parallel reactor system combined with the first principle component analysis enabled fast screening of effective modulators.