Macromolecular Reaction Engineering
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Materials Science Weekly Newsletter
Recently Published Articles
- On the Reaction Characteristics of Miniemulsion Polymerization with Aqueous Phase Initiation – Experiments and Modeling
Tom G. T. Jansen, Jan Meuldijk, Peter A. Lovell and Alex M. van Herk
Article first published online: 18 SEP 2014 | DOI: 10.1002/mren.201400025
Monomer redistribution, droplet disappearance, and narrowing of the particle size distribution have been observed for miniemulsion polymerizations of monomers with different water solubilities, initiated by water-soluble sodium persulfate. These phenomena are mechanistically explained using thermodynamic principles, clearly displaying that a one-to-one copy of monomer droplets into polymer particles is not an intrinsic property of miniemulsion polymerization.
- Effect of Varying Hydrogen Concentration, External Donor Concentration, and Temperature on Propylene Polymerization Kinetics and Microstructure of Polypropylene Made with a 4th Generation Ziegler–Natta Catalyst
Ahmad Alshaiban and João B. P. Soares
Article first published online: 10 SEP 2014 | DOI: 10.1002/mren.201400028
The combined effect of hydrogen and external electron donor concentrations on the tacticity of polypropylene made with a 4th generation Ziegler–Natta catalyst was systematically studied. As illustrated in the figure, the frequency of mmmm pentads increased at higher donor and hydrogen concentrations, but the hydrogen effect was more pronounced at lower donor concentrations.
- An Experimental and Theoretical Investigation of the Ring-Opening Polymerization of L,L-Lactide
Prokopios Pladis, Konstantina Karidi, Theofanis Mantourlias and Costas Kiparissides
Article first published online: 3 SEP 2014 | DOI: 10.1002/mren.201400032
The present study deals with the theoretical and experimental investigation of the ROP of L,L-lactide in the presence of Sn(Oct)2 for the production of high molecular weight PLLA. A comprehensive mathematical model is proposed based on a detailed kinetic mechanism of ROP of L,L-lactide to predict the dynamic evolution of monomer conversion and molecular weight developments.
- Thermal Behavior of Polyethylene Reactor Alloys Polymerized by Ziegler–Natta/Late Transition Metal Hybrid Catalyst
Saeid Ahmadjo, Samaneh Dehghani, Gholam Hossein Zohuri, Gholam Reza Nejabat, Hamed Jafarian, Mostafa Ahmadi and Seyed Mohammad Mahdi Mortazavi
Article first published online: 25 AUG 2014 | DOI: 10.1002/mren.201400024
Ziegler-Natta (ZN) and late transition metal (LTM) hybrid catalysts were synthesized and utilized in preparation of polyethylene (PE) reactor alloys. By changing reaction parameters, versatile thermal behavior from LTM-PE to ZN-PE could be obtained. The proposed method seems to be a promising approach for synthesis of tailor-made polyethylene in a single reactor.
- Poly(Urea–Urethane) Synthesis by Miniemulsion Polymerization Using Microwaves and Conventional Polymerization
Alexsandra Valério, Montserrat Fortuny, Alexandre F. Santos, Pedro H. H. Araújo and Claudia Sayer
Article first published online: 18 AUG 2014 | DOI: 10.1002/mren.201400029
The effect of microwave irradiation during step growth polymerization in miniemulsion to form poly(urea–urethane) nanoparticles is evaluated for different reaction temperatures and polyol types, including oil soluble and water soluble polyols.