Following our previous papers on the mechanism of cyclic esters polymerization induced by tin(II) octoate (Sn(Oct)2) and particularly ε-caprolactone (CL), present work shows that l,l-dilactide/Sn(Oct)2 does not differ mechanistically from CL/Sn(Oct)2 system. Sn atoms bonded through alkoxide groups to macromolecules were also observed MALDI−TOF mass spectrometry. Formation actual initiator Sn(Oct)2 a hydroxy group-containing compound (ROH) was envisaged kinetic arguments. The appropriate...

Kinetics of polymerization l,l-lactide (LA) initiated with aluminum isopropoxide (Al(OiPr)3) trimer (A3) or tetramer (A4) was followed by polarimetry and gel permeation chromatography (GPC). Results the kinetic measurements show that A3 A4 react LA different rates; namely, ki(A3)/ki(A4) ratios (where ki(A3) ki(A4) denote rate constants initiation A4, respectively) determined at 20, 50, 80 (THF solvent), 120 °C (dioxane-1,4 are equal to 2.8 × 103, 8.0 102, 2.9 1.1 respectively. Direct...

Polymerization of ε-caprolactone (CL) initiated with tin(II) octoate (tin(II) 2-ethylhexanoate, (Sn(Oct)2)) in the presence butyl alcohol (BuOH) or water and conducted tetrahydrofuran (THF) as a solvent at 80 °C was studied using MALDI−TOF mass spectrometry. Formation following populations macromolecules revealed: Bu[O(O)C(CH2)5]nOSnOct, Bu[O(O)C(CH2)5]nOct, Bu[O(O)C(CH2)5]nOH, H[O(O)C(CH2)5]nOct, H[O(O)C(CH2)5]nOH, macrocyclics [O(O)C(CH2)5]n, incorporated alkoxide moieties...

Kinetics of polymerization ε-caprolactone (CL) initiated with tin(II) octoate (Sn(Oct)2) in THF as a solvent at 80°C was studied. The results strongly indicate that Sn(Oct)2 proceeds on the tin(II)-alkoxide bond and are not compatible mechanism which propagation proposed to proceed by nucleophilic attack …OH ended macromolecules monomer-Sn(Oct)2 complex.

Abstract A general kinetic treatment of the system with intermolecular chain transfer followed by fast reinitiation is given. It leads to broadening molecular weight distribution (MWD), number growing chains being invariable. Thus, this can be considered as a special case living polymerization. method has been elaborated allowing determination ratio rate constant propagation ( k p ) bimolecular (2) tr from dependence MWD on monomer conversion. Numerical values / equal ≈ 10 2 and 25 were thus...

The kinetics and mechanism of l,l-dilactide (LA) polymerization, initiated with tin(II) butoxide (Sn(OBu)2) carried out in THF solvent (from 20 to 80 °C) or bulk (at 120 °C), were studied. Polarimetric size exclusion chromatography (SEC) measurements showed that initiation was fast quantitative; termination intramolecular transesterification (backbiting) not observed. According the 1H NMR MALDI-TOF spectra analysis, both alkoxide groups Sn(OBu)2 converted into poly(l-lactide) (PLA) growing...

Following our previous papers on the mechanism of ε-caprolactone (CL) and l,l-lactide (LA) polymerization initiated by tin(II) octoate [(tin(II) bis(2-ethylhexanoate), (Sn(Oct)2)] in presence hydroxyl-group-containing compounds [H2O, alcohols or hydroxy-carboxylic acids (ROH)] present work shows that CL LA/Sn(Oct)2/primary amine (RNH2) system, principle, does not differ mechanistically from LA/Sn(Oct)2/ROH system. 1H NMR, matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF)...

The kinetics of bulk polymerization 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones initiated with a zinc 2-ethylhexanoate/butyl alcohol system at 100 °C was studied compared that lipase-catalyzed polymerization. Instantaneous concentrations the lactone monomers were determined on basis relative intensities signals in 1H NMR spectra (500 MHz, CDCl3 as solvent, room temperature) from ω-methylene protons (−(CH2)x-1CH2OC(O)−) (where x = 4, 5, 7, 10, 11, 14, 15) monomer polyester repeating...

Mechanism of initiation and propagation in polymerization ϵ-caprolactone L,L-dilactide induced with tin(II) octoate (Sn(Oct)2) Sn(Oct)2/n-butyl alcohol system is presented. Tin(II) alkoxide bond formation required reaction Sn(Oct)2 hydroxyl group containing compound to form a true initiator. Then end an active centre the further propagation.

Ultra High Molecular Weight Polyethylene (UHMWPE) is a semi-crystalline polymer that has remarkable properties of high mechanical properties, excellent wear resistance, low friction and chemical it found in many applications such sporting goods, medical artificial joints, bullet proof jackets armours, ropes fishing lines [1]. UHMWPE parts cannot be produced easily by conventional processes because its very melt viscosity resulting from long chains [2]. Additive Manufacturing (AM) moving...

Abstract Recent advances in the controlled ring‐opening polymerization of aliphatic cyclic esters are briefly reviewed. Particular attention is paid to high molecular weight linear, branched, and star‐shaped poly(lactide)s poly(ε‐caprolactone) synthesis. It concluded that despite plethora initiating and/or catalytic systems applied for this purpose best results so far were achieved with Al‐ Sn(II) derivatives. Analytical methods employed polyesters various architectures characterization,...

Abstract In‐line rotor stator mixers differ from in‐tank versions because the flow is often controlled independently of speed. For devices turbulent power can be adequately described by single impeller type number. an in‐line rotor‐stator mixer it found that transmitted consists a term and term. The constants in this expression are normally obtained multilinear regression large matrix experiments. Two simplified methods obtaining these limited data sets (1) torque measurement (2) heat...

Abstract In‐line rotor–stator mixers are widely applied in industry for the formulation of emulsion products; however, current understanding breakage/coalescence such devices is limited. In this study effect rotor speed, flow rate and dispersed phase viscosity on drop size distributions an industrial a lab scale in‐line Silverson mixer were investigated. Silicone oils with viscosities 9.4 339 mPa s at 1 wt.% emulsified surfactant solution. Sauter mean diameters correlated various parameters...

The effect of scale, processing conditions, interfacial tension and viscosity the dispersed phase on power draw drop size distributions in three in-line Silverson rotor–stator mixers was investigated with aim to determine most appropriate scaling up parameter. largest mixer a factory scale device, whilst smallest laboratory mixer. All were geometrically similar fitted double rotors standard emulsor stators. 1 wt.% silicone oils viscosities 9.4 mPa s 339 aqueous solutions surfactant or...

Ultra-high molecular weight polyethylene (UHMWPE) is a thermoplastic semicrystalline polymer that has outstanding mechanical properties, low friction coefficient, excellent wear resistance, and highly resistant to corrosive chemicals. UHMWPE found in many applications including artificial joints filtration. However, parts cannot be produced easily by traditional techniques, such as injection moulding extrusion because of its very high melt viscosity owing the extremely long chains. Few...

We investigate the use of Random Forest (RF) regression to estimate viscoelastic constitutive model parameters using Large Amplitude Oscillatory Shear (LAOS). deploy RF predict spectra Chebyshev coefficients. test three models: linear and exponential Phan-Thien-Tanner models, RoLiE-Poly model. For both PTT predicts from with high accuracy. model, lower predictive accuracy is observed, however predicted still accurately capture rheological behaviour in shear extensional flow. This because...

We demonstrate optical coherence tomography (OCT) velocimetry with in-line processing of complex fluids for the first time. The OCT measurements were performed on a perspex section test rig containing ∼40 L fluids, analogous to real-world manufacturing conditions. Opaque solutions lamellar surfactant gel networks (LGNs) and powdered milk explored. Velocity profiles characteristic power law found in LGNs, good agreement independent flow rate off-line determination viscosity. velocity...

Abstract Chain transfer processes (k tr ) taking place in the polymerization (anionic and pseudoanionic) of cyclic esters (lactones) are reviewed. These reactions mostly responsible for departure these systems from fully controlled (living) polymerizations. The ratios k p /k have been determined a number initiating structures growing species related to their selectivity, expressed by . It has shown that less reactive more sterically crowded active polymerize selectively.