Dynamic Simulation of Batch Polymerization Reactor and Sensitivity Analysis of Styrene Homopolymerization

Provedena je dinamička simulacija rada šaržnog polimerizacijskog reaktora za proces homopolimerizacije stirena u otopini ksilena iniciranog uz monofunkcijski i difunkcijski peroksidni inicijator. Monofunkcijski inicijator ima široku industrijsku primjenu, dok je difunkcijski u preliminarnim istraživanjima pokazao određene prednosti kao što su proizvodnja polimera homogenije strukture uz postizanje visokih ili čak potpunih konverzija monomera. Također, vrijeme reakcije može se znatno smanjiti bez potrebe za preinakom reaktorskog sustava. Računalna simulacija provedena je primjenom programskog sustava za simuliranje procesa ChemCAD, točnije njegova modula CC-Polymer, razvijenog isključivo za analizu i projektiranje radikalskih i stupnjevitih polimerizacijskih sustava. Na temelju kompleksnih kinetičkih modela program omogućava predviđanje osnovnih strukturnih svojstava polimera – raspodjele (disperznosti) i prosjeka molekulskih masa, koji izravno određuju kvalitetu i primjenu gotovih proizvoda. Ovisnosti konverzije monomera i strukturnih značajki polimera o vremenu polimerizacije izračunate računalnom simulacijom uspoređene su s eksperimentalno dobivenim rezultatima. Dobivene su istovjetne tendencije i razmjerno dobro slaganje za završetak polimerizacije pri većini ispitanih uvjeta. Provedena je i parametarska analiza za homopolimerizacijski sustav iniciran diperoksidnim inicijatorom. Ispitan je utjecaj koncentracije monomera, koncentracije inicijatora, temperature i vremena reakcije na konverziju monomera, brojčani i maseni prosjek molarnih masa te disperznost.In this work, dynamic simulations of a batch reactor in the process of styrene homopolymerization in a xylene solution initiated with two types of peroxide initiators, monofunctional and bifunctional, was carried out. The monofunctional peroxide initiator has wide industrial applications, while the bifunctional initiator in preliminary studies has shown some advantages, such as the production of polymers with homogeneous structure along with achieving high or even complete conversion of monomers. Additionally, the reaction time can be significantly reduced with no modification of the reactor system. Computer simulation was performed using ChemCAD software for simulation of the chemical process and its integrated modules CC-Polymer developed exclusively for the analysis and design of radical and step polymerization processes. This software package based on the previously developed very complex kinetic models predicts the basic structural properties of polymers such as molar mass and its distribution (dispersity), which directly determines the quality and use of the final product. Dependencies of monomer conversion and structural characteristics of the polymers on the polymerization time obtained by computer simulation were compared with the experimental data. The satisfactory tendencies and a relatively good agreement were accomplished regarding the end of polymerization for most of the examined conditions. Additionally, a sensitivity study for homopolymeric system initiated with diperoxide initiator was performed. The effects of monomer concentration, initiator concentration, temperature and reaction time on the rate of polymerization (monomer conversion) and the main structural properties of polymers were examined

Preparation and Characterization of Electrospun PCL/Silk Fibroin Scaffolds

Natural polymer-based scaffolds are generally considered as favourable matrices for the adhesion and growth of cells in tissue repair. One of the most popular materials in this respect is silk fibroin, known for its wide usage in biomedical applications. This work focuses on the development of electrospun scaffolds based on poly(ε-caprolactone) (PCL) and silk fibroin (SF) evaluated regarding the SF effect on their morphology, surface wetting ability, thermal properties, and HaCaT model cell line biocompatibility. The study revealed that the lowest PCL/SF concentration resulted in highest bead-like morphology formation, relatively thick fibers with the presence of random beads in the case of PCL, while uniform and thinner fibers in the case of increasing PCL/SF content scaffolds. The addition of SF reduced the degree of crystallinity in the PCL due to the less organized crystal structure, and decreased its thermal stability. Both SEM and MTT analyses showed cell presence on all scaffolds three days after cell seeding. Although SF improved PCL hydrophilicity, as shown quantitatively by the MTT assay for improved cytocompatibility properties, more structured electrospun PCL/SF scaffold strategies are required. This work is licensed under a Creative Commons Attribution 4.0 International License

Dynamic Simulation of Batch Polymerization Reactor and Sensitivity Analysis of Styrene Homopolymerization

In this work, dynamic simulations of a batch reactor in the process of styrene homopolymerization in a xylene solution initiated with two types of peroxide initiators, monofunctional and bifunctional, was carried out. The monofunctional peroxide initiator has wide industrial applications, while the bifunctional initiator in preliminary studies has shown some advantages, such as the production of polymers with homogeneous structure along with achieving high or even complete conversion of monomers. Additionally, the reaction time can be significantly reduced with no modification of the reactor system. Computer simulation was performed using ChemCAD software for simulation of the chemical process and its integrated modules CC-Polymer developed exclusively for the analysis and design of radical and step polymerization processes. This software package based on the previously developed very complex kinetic models predicts the basic structural properties of polymers such as molar mass and its distribution (dispersity), which directly determines the quality and use of the final product. Dependencies of monomer conversion and structural characteristics of the polymers on the polymerization time obtained by computer simulation were compared with the experimental data. The satisfactory tendencies and a relatively good agreement were accomplished regarding the end of polymerization for most of the examined conditions. Additionally, a sensitivity study for homopolymeric system initiated with diperoxide initiator was performed. The effects of monomer concentration, initiator concentration, temperature and reaction time on the rate of polymerization (monomer conversion) and the main structural properties of polymers were examined

Room temperature fabrication and post-impregnation of LMO-ST composites:engineering and modeling of dielectric properties

Abstract In this work, the effect of changing the Li2MoO4-SrTiO3 (LMO-ST) compositional proportion (1–100 wt%) on the microstructure, dielectric properties, and relative density of LMO-ST composites fabricated at room temperature was investigated. The results showed that increasing the LMO binder content resulted in a higher relative density (up to 93%), but a lower dielectric constant in the range of 75 to 5. Good agreement between the experimental results and the predicted values of relative permittivity was obtained using the Lichtenecker model, reformulated for a three-phase composite system. Modeling further explained the detrimental effects of porosity on the dielectric properties. To address this issue, impregnation with titanium (IV) isopropoxide (TTIP) was found to reduce overall porosity and improve relative permittivity from 72 to 99 at 1 MHz. The room temperature fabrication offers a wide range of relative permittivity for LMO-ST composites