Catalysis
Farabi Hossain; Md Enamul Hoque
Abstract
This mini-review addresses the burgeoning requirements for environmentally friendly processes in the polymer industry, focusing on recent progress in developing catalytic systems for sustainable olefin polymerization. Improvements in homogeneous and heterogeneous catalyst design have resulted in greater ...
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This mini-review addresses the burgeoning requirements for environmentally friendly processes in the polymer industry, focusing on recent progress in developing catalytic systems for sustainable olefin polymerization. Improvements in homogeneous and heterogeneous catalyst design have resulted in greater control over polymer properties (molecular weight, tacticity, comonomer incorporation). Particularly, Group 4 metallocene and post-metallocene catalysts have enjoyed high activity and a degree of control over polymer microstructure. Late transition metal catalysts (nickel and palladium complexes in particular) afford unique advantages in producing branched polyethylene and conducting polymerizations in polar solvents. Computational studies and novel support strategies have yielded improvements for heterogeneous Ziegler-Natta catalysts. Potential for reducing environmental impact through green catalysis approaches include enzyme-based systems, ionic liquids, and photoactivated catalysts. These catalytic advances have permitted previously unavailable control over polymer properties, including molecular weight distribution and functional group incorporation. Challenges remain regarding the stability of the catalysts, incorporation of comonomer, and economic feasibility. Future work focuses on new ligand design, extending the monomer scope to include renewable feeds tocks and improving the activation procedures. There is a critical need to integrate computational modeling, machine learning, and advanced characterization techniques to facilitate catalyst discovery and understanding of complex structure-property relationships. In general, this review demonstrates the ongoing development of olefin polymerization toward more sustainable practices and describes the important role of advanced catalytic systems in determining the future of the polymer industry).
Food Packaging
Ali Sefa Onsekizoglu; Ali Durmus; Ferhat Şen; Memet Vezir Kahraman; Ismail Aydin
Abstract
In this study, LDPE compounds were prepared using different types of solid and liquid natural additives by melt compounding method. Spent coffee ground (SCG) and organoclay (OCL) powders were used as bio-based and mineral-based solid additives, respectively. Carvacrol and Liquidambar orientalis ...
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In this study, LDPE compounds were prepared using different types of solid and liquid natural additives by melt compounding method. Spent coffee ground (SCG) and organoclay (OCL) powders were used as bio-based and mineral-based solid additives, respectively. Carvacrol and Liquidambar orientalis (LO) oil were used as functional liquid additives. Morphological, thermal, mechanical, viscoelastic, and antimicrobial properties of samples were characterized with various analytical methods and the effects of solid and liquid additive combinations on the physical properties of film samples were quantified. It was observed that the SCG and LO oil made the film color darker but s till transparent. Contact angle measurements indicated that the liquid additives increased the hydrophilicity of LDPE films. Based on the thermal and physical tests, it was found that the solid additives acted as reinforcing agents in LDPE matrix but liquid additives significantly modified the physical properties of LDPE composite films such as increasing the elongation and recovery rates and decreasing the creep strength as well as the improving the antimicrobial properties. The analysis of antimicrobial properties of samples using gram-positive and gram-negative bacteria exhibited that the carvacrol and LO oil significantly inhibited the bacterial growth. This study showed that transparent and antimicrobial flexible packaging films with thermal and mechanical durability could be prepared using sustainable, natural, and waste materials.
Membrane
Ahmed Fadhil Jumaah; Reza Abedini
Abstract
Propylene is a widely used compound in various industrial applications, but its separation from propane, which is often associated with it, remains a significant challenge. Among the separation methods, membrane technology, particularly polymeric membranes, offers an attractive solution due to its relatively ...
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Propylene is a widely used compound in various industrial applications, but its separation from propane, which is often associated with it, remains a significant challenge. Among the separation methods, membrane technology, particularly polymeric membranes, offers an attractive solution due to its relatively low cos t and simplicity. In this study, hydroxyl-functionalized graphene (G─OH) nanosheets were used as an additive in a Pebax 1657 matrix. The results from Fourier Transform Infrared Spectroscopy (FTIR) revealed that the interaction between Pebax and G─OH is physical, characterized by a shift in some peaks due to hydrogen bonding. The proper dispersion of G─OH in the Pebax matrix was confirmed by Differential Scanning Calorimetry (DSC), which also showed an increase in the glass transition temperature (Tg), indicating the rigidity of Pebax chains in the presence of G─OH. Thermogravimetric Analysis (TGA) results demonstrated that the degradation temperatures (Td) of Pebax/ G─OH 1 wt.% and Pebax/G─OH 2 wt.% membranes were 335°C and 330°C, respectively. A comprehensive gas permeation study, including pure and mixed gas tests at feed pressures of 2, 6, and 10 bar, as well as a long-term stability test, was conducted on the membranes. Among all the MMMs, Pebax/G─OH 1.5 wt.% demonstrated the best gas separation performance, achieving a propylene permeability of 89.8 barrer and a C3H6/C3H8 selectivity of 9.8. Additionally, under mixed gas permeation tests (50:50 v/v of C3H6 and C3H8), this membrane exhibited a propylene permeability of 76.3 barrer and a C3H6/C3H8 selectivity of 8.8. Finally, the performance of the MMMs in C3H6/C3H8 separation was benchmarked against the Robeson upper bound curve.
Polyolefin degradation
Marzieh Alidadi-Shamsabadi; Shirin Shokoohi; Mahnaz Shahzamani; Homa Abbasian-Peykani
Abstract
In this work, the photo-aging behavior of high impact polystyrene (HIPS), polystyrene/ethylene propylene diene monomer (PS/EPDM) binary blends, and compatibilized polystyrene/ethylene propylene diene monomer/ polyamide 6 (PS/EPDM/PA6) ternary blends was studied and compared together. Photo-degradation ...
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In this work, the photo-aging behavior of high impact polystyrene (HIPS), polystyrene/ethylene propylene diene monomer (PS/EPDM) binary blends, and compatibilized polystyrene/ethylene propylene diene monomer/ polyamide 6 (PS/EPDM/PA6) ternary blends was studied and compared together. Photo-degradation of polymer blends faces considerable challenges, because a polymer blend is a compound of multiple components with particular interactions and its components may function as degrading or stabilizing agents. Photo-aging generally can cause changes in the color and mechanical properties of polymer compounds. Attenuated total reflection Fourier transform spectroscopy (ATR-FTIR) was conducted to study the chemical interactions between components in the prepared samples. The morphological structure of blends was studied by using scanning electron microscopy (SEM). The impact and tensile strength of the samples were measured and compared after exposure to UV radiation. To study the changes in the appearance, the yellowness index values of the samples were followed at different periods of exposure to UV irradiation. The post-radiation results showed similar mechanical performance of ternary and binary blends with the retention of mechanical properties close to each other. The impact strength and elongation-at-break for the HIPS sample were greatly reduced compared to the blends, showing their retention by 8.46 and 7.86%, respectively. The ultimate tensile strength retention in each sample is between 70 and 82% and there is no significant difference between them. The final yellowness index of HIPS was measured to be 1.6 and 1.2 times higher than that of the binary and ternary blends, respectively.
Composites and nanocomposites
Ali Yakoub Alkhair; Emiru Yidnekachew Melesse; Irina Anatol'evna Kirsh; Yulia Aleksandrovna Filinskaya; Izabella Sergeevna Tveritnikova; Oleg Igorevich Mihryachev
Abstract
Bio-composite from linear low-density polyethylene (LLDPE) with lysozyme, mixed lysosome and glucose oxidase enzymes was synthesized through the melt extrusion system, respectively. The aim of this work was evaluation and characterization of the effect of lysosome, mixed lysosome and glucose oxidase ...
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Bio-composite from linear low-density polyethylene (LLDPE) with lysozyme, mixed lysosome and glucose oxidase enzymes was synthesized through the melt extrusion system, respectively. The aim of this work was evaluation and characterization of the effect of lysosome, mixed lysosome and glucose oxidase enzymes on the mechanical, water vapor transfer rate, and structural appearance of the Bio based LLDPE composite films. Along this line, 50 g of LLDPE pellets incorporated with 1%, 5%, and 10% (w/w) of lysozyme alone, mixed lysosome and glucose oxidase were examined, apparently. Pure LLDPE was used as a control. Over all, biocomposite with 5 and 10%(w/w) of mixed lysosome and glucose oxidase enzymes did not result in good outcome and not even enough for characterization. The surface structure of biocomposites was examined through the digital microscopy for identify dispersion of enzymes inside the LLDPE matrix and at higher concentration (10w/w%) dense and large surface are formed. However, good dispersion and reinforcing activity of enzymes in the LLDPE matrix was noticed with small concentration of lysosome (1, and 5w/w%) enzymes. The mechanical strength and elongation at break of biocomposite composite films were found to increase with small concentration (1 and 5 w/w%), but decrease with increasing of enzyme concentration. Averagely, the WVTR showed increase as the enzyme concentration increased. Besides, the Fourier-transform infrared spectroscopy (FTIR) was used to determine structural configuration of the enzymes in LDPE matrix; single sharp stretching breaks at 570 cm-1 with 1, 5 and 10 wt.% was corresponded to the existence of enzyme bands. All in one, the addition of lysozomes and glucose oxidase in small concentration has high potential in development of biocomposite relative to the traditional plastic composites.
Composites and nanocomposites
Reza Naghdi; Tahereh Nejat
Abstract
The ever-increasing environmental constraints over waste disposal led us to study the feasibility of valorizing bagasse/ polypropylene composites via nanosilica and mercerization treatments. Water absorption and thickness swelling of the nanocomposites improved due to the barrier properties of nanosilica ...
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The ever-increasing environmental constraints over waste disposal led us to study the feasibility of valorizing bagasse/ polypropylene composites via nanosilica and mercerization treatments. Water absorption and thickness swelling of the nanocomposites improved due to the barrier properties of nanosilica particles. FTIR spectra revealed decreased hydroxyl groups as well as carbonyl groups disappearance after alkali treatment. Except for impact strength, the combined nanosilica-mercerization treatment could enhance the mechanical performance of the biocomposites. Thermogravimetric analysis showed higher degradation temperatures and residual char yields after the combined nanosilica-mercerization treatment. Furthermore, differential scanning calorimetry indicated that the individual mercerization and nanosilica treatments had no distinct effect on the thermal performance of the composites, whereas the combined treatment brought about marked improvements in the given properties, e.g; melting and crystallization temperatures and crystallinity rate. The present study introduces a novel technique to valorize a totally waste-based bagasse/ polypropylene composite material holding a promising potential for various industrial applications.
