Polymerization and Polymer Modification Reactions in Near and Supercritical Fluids

Kiran, Erdoǧan

doi:10.1007/978-94-011-3929-8_10

Cited by 7 publications

(8 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, SCF technology recently has made significant improvements to this field, both in processing of blends and polymerization of blends (primarily through impregnation of monomer as discussed earlier). Although carbon dioxide-assisted polymerization and reactive blending have become a very successful method to generate novel blends, , we concentrate in this review on the physical processing of polymers.…”

Section: Applicationsmentioning

confidence: 99%

A Review of CO₂ Applications in the Processing of Polymers

Tomasko

Liu

et al. 2003

Ind. Eng. Chem. Res.

638

488

View full text Add to dashboard Cite

The use of supercritical carbon dioxide as a processing solvent for the physical processing of polymeric materials is reviewed. Fundamental properties of CO2/polymer systems are discussed with an emphasis on available data and measurement techniques, the development of theory or models for a particular property, and an evaluation of the current state of understanding for that property. Applications such as impregnation, particle formation, foaming, blending, and injection molding are described in detail including practical operating information for selected topics. The review concludes with some forward-looking discussion on the future of CO2 in polymer processing.

show abstract

Section: Applicationsmentioning

confidence: 99%

A Review of CO₂ Applications in the Processing of Polymers

Tomasko

Liu

et al. 2003

Ind. Eng. Chem. Res.

638

488

View full text Add to dashboard Cite

show abstract

“…2 There are a number of studies on the synthesis, processing, modification and purification of synthetic and natural polymers in scCO 2 . [3][4][5][6][7][8] Polymers obtained at the end of polymerization have low solubilities in scCO 2 . This issue has brought about many heterogeneous polymerization processes, such as precipitation, emulsion, suspension and dispersion polymerizations.…”

Section: Introductionmentioning

confidence: 99%

Ring-opening copolymerization of L-lactide and ɛ-caprolactone in supercritical carbon dioxide using triblock oligomers of caprolactone and PEG as stabilizers

Yılmaz

Eğri

Yıldız

et al. 2011

Polym J

View full text Add to dashboard Cite

In this study, the use of triblock (A-B-A) oligomers of e-caprolactone (e-CL) (A) and PEG400 (B) as stabilizers (SB) for the copolymerization of L-lactide (LLA) and e-CL in supercritical carbon dioxide (scCO 2 ) was investigated. To determine the effect of CO 2 -philic and polymer-philic segments on copolymerization, oligomers with three different average molecular weights (M w ¼2000-6000 Da) were synthesized by changing the PEG400/e-CL ratio. Copolymerizations were confirmed by 1 H-nuclear magnetic resonance (NMR), 13 C-NMR and differential scanning calorimeter data. It was possible to copolymerize LLA and e-CL in scCO 2 without any SB; however, the polymerization yields and average molecular weights were low, and significant aggregate formations were detected. Recipes featuring only 5% SB were successfully applied to reach high polymerization yields of B85% and polymers with average molecular weights greater than 20 kDa. When the polymer-philic segment of the SB increased, both the yield and molecular weight of the copolymer also increased significantly, resulting in white powdery products.

show abstract

“…The kinetics of phase separation in polymers is an area of intense research activity. The interest is both theoretical and practical. − Among the reasons is the desire to understand the time evolution of microstructure development so that practical methodologies can be developed for pinning the nonequilibrium transient structures for specific end uses. The majority of the studies reported in the literature have been on the kinetics of phase separation in “polymer + polymer” blend systems where structure development and morphology control are of great importance. ,,− Relatively little work has been done in phase separation kinetics in “polymer + solvent” systems.…”

Section: Introductionmentioning

confidence: 99%

Pressure-Induced Phase Separation in Polymer Solutions: Kinetics of Phase Separation and Crossover from Nucleation and Growth to Spinodal Decomposition in Solutions of Polyethylene in n-Pentane

Liu

Kiran

2001

Macromolecules

View full text Add to dashboard Cite

The kinetics of pressure-induced phase separation (PIPS) in solutions of polyethylene (M w = 108 000, PDI = 1.32) in n-pentane has been studied using time- and angle-resolved light scattering. Controlled pressure quench experiments were conducted at different polymer concentrations (0.49, 0.97, 2.07, 2.8, 4.1, 5.0, and 10.8% by mass) to determine both the binodal and spinodal envelopes and the critical polymer concentration. At each concentration, a series of rapid pressure quenches with different depths of penetration into the region of immiscibility were imposed, and the time evolutions of the scattered light intensities were followed to determine the pressure below which the mechanism changes from “nucleation and growth” to “spinodal decomposition”. The crossover is identified from the characteristic fingerprint scattering patterns associated with each mechanism. The spinodal decomposition process is characterized by the formation and evolution of a spinodal ring during phase separation that leads to a maximum in the angular variation of the scattered light intensity. The nucleation and growth mechanism is characterized by the absence of such a maximum and the continual decrease of the scattered light intensities with increasing angles. The time scale of new phase formation and growth is shown to be relatively short. The late stage of phase separation is entered within seconds. For quenches leading to spinodal decomposition, the characteristic wavenumber q m corresponding to the scattered light intensity maximum I m is observed to be nonstationary, moving to lower wavenumbers after a very short elapsed time. The growth of domain size is observed to follow power-law-type scaling with q m ∼ t -α and I m ∼ t β with β ≈ 2α. In the intermediate and late stages, the domain size is found to grow from 4 to 14 μm within 5 s. Analysis of the early stage of phase separation according to Cahn−Hilliard theory shows that the diffusion coefficients are in the range of (1−9) × 10-12 m2/s and depend on the quench depth.

show abstract

Polymerization and Polymer Modification Reactions in Near and Supercritical Fluids

Cited by 7 publications

References 30 publications

A Review of CO₂ Applications in the Processing of Polymers

A Review of CO₂ Applications in the Processing of Polymers

Ring-opening copolymerization of L-lactide and ɛ-caprolactone in supercritical carbon dioxide using triblock oligomers of caprolactone and PEG as stabilizers

Pressure-Induced Phase Separation in Polymer Solutions: Kinetics of Phase Separation and Crossover from Nucleation and Growth to Spinodal Decomposition in Solutions of Polyethylene in n-Pentane

Contact Info

Product

Resources

About

Polymerization and Polymer Modification Reactions in Near and Supercritical Fluids

Cited by 7 publications

References 30 publications

A Review of CO2 Applications in the Processing of Polymers

A Review of CO2 Applications in the Processing of Polymers

Ring-opening copolymerization of L-lactide and ɛ-caprolactone in supercritical carbon dioxide using triblock oligomers of caprolactone and PEG as stabilizers

Pressure-Induced Phase Separation in Polymer Solutions: Kinetics of Phase Separation and Crossover from Nucleation and Growth to Spinodal Decomposition in Solutions of Polyethylene in n-Pentane

Contact Info

Product

Resources

About

A Review of CO₂ Applications in the Processing of Polymers

A Review of CO₂ Applications in the Processing of Polymers