scholarly journals The Mechanics of Forming Ideal Polymer–Solvent Combinations for Open-Loop Chemical Recycling of Solvents and Plastics

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 112
Author(s):  
Ioannis Tsampanakis ◽  
Alvin Orbaek White
Keyword(s):  
Acrylonitrile Butadiene Styrene ◽  
Batch Process ◽  
Energy Difference ◽  
Relative Energy ◽  
Linear Increase ◽  
Open Loop ◽  
Dissolution Process ◽  
Dissolution Mechanism ◽  
Chemical Recycling ◽  
Multiple Sources

The inherent value and use of hydrocarbons from waste plastics and solvents can be extended through open-loop chemical recycling, as this process converts plastic to a range of non-plastic materials. This process is enhanced by first creating plastic–solvent combinations from multiple sources, which then are streamlined through a single process stream. We report on the relevant mechanics for streamlining industrially relevant polymers such as polystyrene (PS), polypropylene (PP), high-density polyethylene (HDPE), and acrylonitrile butadiene styrene (ABS) into chemical slurries mixed with various organic solvents such as toluene, xylene, and cyclohexane. The miscibility of the polymer feedstock within the solvent was evaluated using the Relative Energy Difference method, and the dissolution process was evaluated using the “Molecular theories in a continuum framework” model. These models were used to design a batch process yielding 1 tonne/h slurry by setting appropriate assumptions including constant viscosity of solvents, disentanglement-controlled dissolution mechanism, and linear increase in the dissolved polymer’s mass fraction over time. Solvent selection was found to be the most critical parameter for the dissolution process. The characteristics of the ideal solvent are high affinity to the desired polymer and low viscosity. This work serves as a universal technical guideline for the open-loop chemical recycling of plastics, avoiding the growth of waste plastic by utilising them as a carbon feedstock towards a circular economy framework.

scholarly journals The Mechanics of Forming Ideal Polymer Solvent Combinations for Open-Loop Chemical Recycling of Plastics and Solvents

2021 ◽  
Author(s):  
Ioannis Tsampanakis ◽  
Alvin Orbaek White
Keyword(s):  
Acrylonitrile Butadiene Styrene ◽  
Batch Process ◽  
Energy Difference ◽  
Relative Energy ◽  
Linear Increase ◽  
Open Loop ◽  
Dissolution Process ◽  
Dissolution Mechanism ◽  
Chemical Recycling ◽  
Multiple Sources

The inherent value and use of hydrocarbon from waste plastics and solvents can be extended through open-loop chemical recycling as this process converts plastic to range of non-plastic materials. This process is enhanced by first creating plastic-solvent-combinations from multiple sources which are then streamlined through single process stream. We report on the relevant mechanics for streamlining industrially relevant polymers such as polystyrene (PS), polypropylene (PP), high-density polyethylene (HDPE) and acrylonitrile butadiene styrene (ABS) into chemical slurries mixed with various organic solvents such as toluene, xylene and cyclohexane. The miscibility of the polymer feedstock within the solvent was evaluated using the Relative Energy Difference method, and the dissolution process was evaluated using the “Molecular theories in a continuum framework” model. These models were used to design a batch process yielding 1 tonne/h slurry by setting appropriate assumptions including constant viscosity of solvents, disentanglement-controlled dissolution mechanism and linear increase of the dissolved polymer’s mass fraction over time. Solvent selection was found to be the most critical parameter for the dissolution process. The characteristics of the ideal solvent are high affinity to the desired polymer and low viscosity. This work serves as a universal technical guideline for open-loop chemical recycling of plastics avoiding the growth of waste plastic in a circular economy framework.

PENGGUNAAN AIR SUPER KRITIS PADA DEPOLIMERISASI NYLON-12 (BATCH PROCESS)

2018 ◽  
Vol 5 (3) ◽  
Author(s):  
Mohamad Yusman
Keyword(s):  
Supercritical Water ◽  
Scale Up ◽  
Experimental Studies ◽  
Reaction System ◽  
Batch Process ◽  
Chemical Recycling ◽  
Water Decomposition ◽  
Product Distributions ◽  
New Process ◽  
Nylon 12

Water at the supercritical state is a new process for the chemical recycling. At this thermodynamic state i.e. Pc = 218 atmospheres and Tc = 374oC , water behaves very differently from its everyday temperament and it is a very good solvent for organic components. Experimental studies show that supercritical water can decompose hydrocarbons/polymers and produce useful products like 2-Azacyclotridecanone /lactam-1 from Nylon-12 (batch process). The decomposition process itself was carried out in batch reaction system in order to get more information about product distributions, time dependence, and scale-up possibilities.Keywords: supercritical water, decomposition, batch, polymer, hydrocarbon

scholarly journals The potential of magnetisation transfer NMR to monitor the dissolution process of cellulose in cold alkali

Cellulose ◽  
2019 ◽  
Vol 26 (18) ◽  
pp. 9403-9412 ◽  
Author(s):  
Maria Gunnarsson ◽  
Merima Hasani ◽  
Diana Bernin
Keyword(s):  
Hydrophobic Interactions ◽  
Dissolution Process ◽  
Mechanistic Study ◽  
Dissolution Mechanism ◽  
Hydroxyl Groups ◽  
Similar Amount ◽  
Magnetisation Transfer ◽  
Promising Alternative ◽  
Nmr Methods ◽  
Increasing Temperature

Abstract Cellulose is the most important biopolymer on earth and, when derived from e.g. wood, a promising alternative to for example cotton, which exhibits a large environmental burden. The replacement depends, however, on an efficient dissolution process of cellulose. Cold aqueous alkali systems are attractive but these solvents have peculiarities, which might be overcome by understanding the acting mechanisms. Proposed dissolution mechanisms are for example the breakage of hydrophobic interactions and partly deprotonation of the cellulose hydroxyl groups. Here, we performed a mechanistic study using equimolar aqueous solutions of LiOH, NaOH and KOH to elucidate the dissolution process of microcrystalline cellulose (MCC). The pH was the highest for KOH(aq) followed by NaOH(aq) and LiOH(aq). We used a combination of conventional and advanced solution-state NMR methods to monitor the dissolution process of MCC by solely increasing the temperature from − 10 to 5 °C. KOH(aq) dissolved roughly 25% of the maximum amount of MCC while NaOH(aq) and LiOH(aq) dissolved up to 70%. Water motions on nanoscale timescales present in non-frozen water, remained unaffected on the addition of MCC. Magnetisation transfer (MT) NMR experiments monitored the semi-rigid MCC as a function of temperature. Interestingly, although NaOH(aq) and LiOH(aq) were able to dissolve a similar amount at 5 °C, MT spectra revealed differences with increasing temperature, suggesting a difference in the swollen state of MCC in LiOH(aq) already at − 10 °C. Furthermore, MT NMR shows a great potential to study the water exchange dynamics with the swollen and semi-rigid MCC fraction in these systems, which might give valuable insights into the dissolution mechanism in cold alkali.

scholarly journals Graphene/Carbon Nanotube Hybrid Nanocomposites: Effect of Compression Molding and Fused Filament Fabrication on Properties

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 101 ◽  
Author(s):  
Sithiprumnea Dul ◽  
Luiz Gustavo Ecco ◽  
Alessandro Pegoretti ◽  
Luca Fambri
Keyword(s):  
Electromagnetic Interference ◽  
Acrylonitrile Butadiene Styrene ◽  
Melt Flow Index ◽  
Compression Molding ◽  
Linear Increase ◽  
Hybrid Nanocomposites ◽  
Flow Index ◽  
Shielding Effectiveness ◽  
Fused Filament Fabrication ◽  
Emi Se

The present work reports on the production and characterization of acrylonitrile butadiene styrene (ABS) hybrid nanocomposite filaments incorporating graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) suitable for fused filament fabrication (FFF). At first, nanocomposites with a total nanofiller content of GNP and/or CNT of 6 wt.% and a GNP/CNT relative percentage ratio of 0, 10, 30, 50, 70, and 100 were produced by melt compounding and compression molding. Their mechanical, electrical resistivity, and electromagnetic interference shielding effectiveness (EMI SE) properties were evaluated. The hybrid nanocomposites showed a linear increase in modulus and decrease in strength as a function of GNP content; on the other hand, the addition of CNT in hybrid nanocomposites determined a positive increase in electrical conductivity, but a potentially critical decrease of melt flow index. Due to the favorable compromise between processability and enhancement of performance (i.e., mechanical and electrical properties), the hybrid composition of 50:50 GNP/CNT was selected as the most suitable for the filament production of 6 wt.% carbonaceous nanocomposites. EMI SE of ABS-filled single CNT and hybrid GNP/CNT nanofillers obtained from compression molding reached the requirement for applications (higher than −20 dB), while slightly lower EMI SE values (in the range −12/−16 dB) were obtained for FFF parts dependent on the building conditions.

scholarly journals MOCCA-SURVEY Database I: Dissolution of tidally filling star clusters harboring black hole subsystem

2019 ◽  
Vol 14 (S351) ◽  
pp. 438-441 ◽  
Author(s):  
Mirek Giersz ◽  
Abbas Askar ◽  
Long Wang ◽  
Arkadiusz Hypki ◽  
Agostino Leveque ◽  
...  
Keyword(s):  
Black Hole ◽  
Star Clusters ◽  
Mass Function ◽  
Stellar Mass ◽  
Star Cluster ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Dissolution Process ◽  
Dissolution Mechanism ◽  
Dynamical Equilibrium

AbstractWe investigate the dissolution process of star clusters embedded in an external tidal field and harboring a subsystem of stellar-mass black hole. For this purpose we analyzed the MOCCA models of real star clusters contained in the Mocca Survey Database I. We showed that the presence of a stellar-mass black hole subsystem in tidally filling star cluster can lead to abrupt cluster dissolution connected with the loss of cluster dynamical equilibrium. Such cluster dissolution can be regarded as a third type of cluster dissolution mechanism. We additionally argue that such a mechanism should also work for tidally under-filling clusters with a top-heavy initial mass function.

Experimental Research on the Solubility of Cellulose in Different Ionic Liquids

2013 ◽  
Vol 690-693 ◽  
pp. 1568-1571 ◽  
Author(s):  
Xiao Jun Li ◽  
Yu Shan Sun ◽  
Qiang Zhao
Keyword(s):  
Ionic Liquids ◽  
Dimethyl Sulfoxide ◽  
Experimental Research ◽  
Dissolution Process ◽  
Dissolution Mechanism ◽  
Melting Points ◽  
Mechanical Stirring ◽  
Polarizing Microscope

Solubilities of cellulose in several ionic liquids were investigated by using Thermal Platform Polarizing Microscope (TPPM) and mechanical stirring. The results showed that all the ionic liquids used could dissolve cellulose except 1-ethyl-3-methylimidazolium bromide ([EMIM]Br). The dissolution process of cellulose experienced five steps including infiltration, limited swelled, partially dissolved, dissociation and completely dissolved. Ionic liquids with the cellulose-dissolving temperatures from low to high in sequence was 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac) < 1-butyl-3-methylimidazolium acetate ([BMIM]Ac) < 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) < 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl) < 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) < 1-benzyl-3-methylimidazolium chloride ([BZMIM]Cl), while the solubility reduced in turn and the melting points or viscosities of the ionic liquids increased in the same order. Addition of some N,N-dimethyl sulfoxide to the solvents promoted ionic liquids to dissolve cellulose quickly. When dissolution process was applied by mechanical stirring, cellulose partially swelled and looked like "Lamb skewers" before dissolved. The dissolution mechanism was discussed.

An explanation of the crystal structure of the rare gas solids

1974 ◽  
Vol 336 (1606) ◽  
pp. 365-377 ◽  
Keyword(s):  
Crystal Structure ◽  
Band Structure ◽  
Excited States ◽  
Solid Helium ◽  
Van Der Waals ◽  
Energy Difference ◽  
Relative Energy ◽  
Rare Gas ◽  
Interatomic Potentials ◽  
Starting Point

A new explanation of why the crystal structure of the rare gas solids, Ne, Ar, Kr and Xe is f. c. c. rather than h. c. p. is offered. The magnitude of the relative energy difference, ∆ = ( E f. c. c. – E h. c. p. )/ E t. c. c. , is estimated and it is shown that the effect is numerically large enough in all these solids ( ∆ ≳ + 1 x 10 –3 ) to overcome the small preference of two-body interatomic potentials for the h. c. p. structure ( ∆ ≃ – 10 –4 ). The effect is much weaker in helium and so the h. c. p. structure of solid helium emerges naturally as a consequence of the two-body potential. The explanation depends on the modification of the (long-range) van der Waals energy by the (short-range) overlap of atomic excited states with the neighbouring atoms in the crystal. The resulting crystal field in the f. c. c. and h. c. p. structures splits excited d-states by different amounts. The f. c. c. structure is favoured because the energy split is wider in f. c. c. (which is centrosymmetric) than in h. c. p. (which does not have a centre of symmetry at the atomic sites); the resulting van der Waals attractive energy is thereby greater in f. c. c. An alternative approach is also developed, which uses the band states of the crystal as a starting-point, and yields a similar result. We expect that, if good enough band structure calculations of h. c. p. rare gas solids were available, the best way to estimate the value of ∆ would be to calculate the van der Waals energy in the solid in terms of band structure energies for the excited states and gas phase values for the dipole matrix elements. Preliminary estimates of the size of the effect, based on currently available band structure data, suggest that ∆ ranges from approximately 12 x 10 –4 for Ne to 27 x 10 –4 for Xe; these values are quite sufficient to explain the stability of the f. c. c. structure.

scholarly journals Thermodynamic and Kinetic Studies of Dissolution of Hematite in Mixtures of Oxalic and Sulfuric Acid

2020 ◽  
Author(s):  
Paula Vehmaanperä ◽  
Riina Salmimies ◽  
Antti Häkkinen
Keyword(s):  
Sulfuric Acid ◽  
Reaction Time ◽  
Oxalic Acid ◽  
Solid Phase ◽  
Dissolution Kinetics ◽  
Kinetic Studies ◽  
Original Study ◽  
Dissolution Process ◽  
Dissolution Mechanism ◽  
Efficient Dissolution

Abstract The dissolution of iron oxides in mixtures of acids is fairly uncommon but can result in a more efficient dissolution process. The objective in this work was to investigate the dissolution of synthetic hematite powder in mixtures of oxalic and sulfuric acid. Experiments were done at different acid ratios and temperatures. An increase in temperature from 15 to 35 °C increased solubility, whereas an increase from 35 to 50 °C did not change the solubility but had a profound effect on the kinetics. An important finding was that oxalic acid advanced the dissolution process since increasing the amount of oxalic acid in the system resulted in faster kinetics and higher solubilities. The dissolution kinetics were well described with the Kabai model, which was the only studied model able to describe the whole reaction time. However, the solid specific constant a varied for the different acid ratios and this is argued to be a result of changes in the solid phase. The changes in the constant a were not in line with the original study of Kabai, which indicates that a cannot be the solid specific constant but it can be the constant connected to dissolving media describing the changes in the dissolution mechanism.

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