Abstract
Nano-TiO2 particles with a range of crystallite sizes were synthesized by a conventional sol-gel method, and then used as nanoparticle substrates in the synthesis of LLDPE/TiO2 nanocomposites via in situ polymerization of ethylene/1-hexene with zirconocene/MMAO catalyst. It was found that the size of the nano-TiO2 crystallite nanoparticles can influence the catalytic activity in the polymerization system. The larger nano-TiO2 crystallites provided better catalytic activity in the polymerization system due to more space for monomer attack. In addition, by thermo-gravimetric analysis, it can be seen that the larger nano-TiO2 crystallites also exhibited lower interaction with available MMAO. Consequently, the MMAO reacted more efficiently with the zirconocene catalyst during the activation process, and enhanced polymerization catalysis. All the polymer nanocomposites products did not have well defined melting temperature indicating non-crystalline polymers. This is due to the high amount of hexene incorporation (based on 13C NMR). The difference in crystallite sizes of the nano-TiO2 also affected how 1-hexene became incorporated into the polymer nanocomposites. The smaller crystallite size of nano-TiO2 allowed greater 1-hexene incorporation due to depression of the reactivity of the ethylene. The contribution of this work helps develop a better understanding of the role of nano-TiO2 in the catalytic activity of the polymerization system and in the microstructure of the polymer composite product. However, this study only considers work on the laboratory scale, so for commercial application of these results, it is necessary to scale up the polymerization process. It is only at this stage, that other physical properties, such as the mechanical properties of these materials can be sensibly determined.
Highlights
Nano-TiO2 particles with a range of crystallite sizes were synthesized by a conventional sol-gel method, and used as nanoparticle substrates in the synthesis of LLDPE/TiO2 nanocomposites via in situ polymerization of ethylene/1-hexene with zirconocene/Modified methylaluminoxane (MMAO) catalyst
We have prepared nano-TiO2 particles with controlled variation in crystallite size by a conventional sol-gel method. These nanoparticles were employed as composite reinforcements and as supporting material for the zirconocene/MMAO catalyzed in situ polymerization of ethylene and 1-hexene
It is only at this stage that other physical properties, such as the mechanical properties of these materials can be sensibly determined. It can be concluded from this study that the variation in the size of nano-TiO2 crystallites significantly affects both catalytic activities for the polymerization system and the characteristic properties of the polymer composite product
Summary
Nano-TiO2 particles with a range of crystallite sizes were synthesized by a conventional sol-gel method, and used as nanoparticle substrates in the synthesis of LLDPE/TiO2 nanocomposites via in situ polymerization of ethylene/1-hexene with zirconocene/MMAO catalyst. The synthesis of controlled crystallite size nano-TiO2 can be performed with a conventional sol-gel method [16] This technique allows the control of certain of the nanosolid parameters by setting the parameters before gelation takes place and allowing the preparation of tailor-made nanomaterials [17]. We have prepared nano-TiO2 particles with controlled variation in crystallite size by a conventional sol-gel method These nanoparticles were employed as composite reinforcements and as supporting material for the zirconocene/MMAO catalyzed in situ polymerization of ethylene and 1-hexene. The subject of this paper is how the catalytic activity and properties of the LLDPE/TiO2 nanocomposites vary with nano-titania crystallite size
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