Abstract Summary: Propagation rate coefficients, k p , for free‐radical polymerization of butyl acrylate (BA) previously reported by several groups are critically evaluated. All data were determined the combination pulsed‐laser (PLP) and subsequent polymer analysis size exclusion (SEC) chromatography. The PLP‐SEC technique has been recommended as method choice determination IUPAC Working Party on Modeling Polymerization Kinetics Processes . Application to acrylates proven be very difficult...

A novel method to extract individual free-radical polymerization rate coefficients for butyl acrylate intramolecular chain transfer (backbiting), kbb, and monomer addition the resulting midchain radical, , is presented. The approach measuring kbb does not require knowledge of any other coefficient. Only dispersion parameter SEC broadening has be determined by fitting measured MWDs or should available from separate experiments. based upon analysis shift in position inflection point polymer...

New expressions that account for the formation of acrylate midchain radicals by intramolecular transfer and their subsequent propagation, termination, events have been derived polymerization rate, average chain-length, chain-length distribution under stationary conditions. The nonidealities observed in previous kinetic studies are captured a single lumped rate coefficient, θ, controls apparent order on monomer concentration. Applied to data from literature, treatment yields consistent...

Abstract Butyl acrylate solution polymerization has been studied at 80–170 °C over a range of monomer and initiator levels. A PREDICI model developed to describe the experiments, taking into account chain backbiting, β ‐scission, addition macromonomer. The is used estimate Arrhenius parameters for rate coefficients ‐scission [ ( k ) = (1.49 ± 0.28) × 10 9 s −1 , E 63.9 0.9 kJ · mol ], ratio termination secondary midchain radicals ${\left[ {A(k_{{\rm t}} /k_{{\rm t}}^{{\rm 0.74\pm...

n-Butyl acrylate (BA) starved-feed solution semibatch experiments with varying final polymer content and monomer feed times were carried out at 138 °C. A full mechanistic model of the system implemented in Predici includes intermolecular chain transfer to macromonomer propagation as well backbiting, scission, midchain radical termination. The importance under these conditions industrial interest is illustrated by experiment simulation, reaction responsible for significant increase...

Abstract Unusual difficulties are faced in the determination of propagation rate coefficients ( k p ) alkyl acrylates by pulsed‐laser polymerization (PLP). When backbiting is predominant chain transfer event, apparent determined PLP experiments for different frequencies should range between (propagation coefficient secondary radicals) at high frequency and low frequency. The value could be expressed from kinetic parameters: $k_{\rm p}^{{\rm av}} = k_{\rm p} - {{k_{\rm k_{{\rm p}2} } \over {1...

Abstract The kinetics of butyl acrylate solution polymerization up to high conversion are studied both experimentally and theoretically. New expressions taking into account inter‐ intra‐molecular transfer polymer derived for rate, average chain‐length branching level. These used comparative analysis these two chain events evaluation the backbiting rate coefficient, k bb , constant solvent (xylene), C trS . Using batch experiments performed at 50, 60 70 °C, Arrhenius parameters estimated be,...

Abstract Summary: Procedures are developed to estimate kinetic rate coefficients from available data for the free radical solution polymerization of butyl acrylate at 50 °C. The analysis is based upon a complete mechanistic set that includes formation mid‐chain radicals through backbiting and their subsequent reaction, contains no assumptions on how coefficient cross‐termination end‐chain related two homo‐termination coefficients. After thorough statistical analysis, results fitting combined...

Propagation rate coefficient values, k p , reported by several groups for radical polymerization of bulk vinyl acetate are critically evaluated. All data obtained the combination pulsed‐laser and subsequent polymer analysis size exclusion chromatography, as recommended IUPAC Working Party on Modeling Polymerization Kinetics Processes. Although a small (≈15%) increase in is observed laser pulse repetition increased from low (25–100 Hz) to high (300–500 all fulfill required consistency...

We have investigated the anionic ring-opening multibranching polymerization for hyperbranched polyglycerol using slow monomer addition at 120 °C. Different molecular masses were targeted, and reaction mixture was probed regular intervals experimental data. The resulting polymers characterized by gel permeation chromatography, mass spectrometry, NMR spectroscopy. A computational PREDICI model of developed to describe parameter dependencies. rate coefficients determined thermal base-catalyzed,...

The radical propagation kinetics of vinyl acetate (VAc) has been studied by pulsed-laser polymerization coupled with analysis the resulting polymer molar mass distributions. significant increase in apparent rate coefficient observed increasing pulse repetition is explained influence head-to-head defects formed during chain growth. Simulations that include monomer addition are combined an experimental results to estimate subsequent coefficients for reaction resultant as well normal...

Abstract A new approach for the simulation of PLP (pulsed laser polymerization) is presented. This allows one to obtain analytical solutions different polymerization schemes, including either chain transfer monomer or intramolecular polymer. The first results experiments on n ‐butyl acrylate at 20 °C and ambient pressure are MWDs simulated acrylate, in bulk using three models: model with polymer (solid line), (dashed classical (dotted line). image

A numerical approach has been developed to capture the inhomogeneous and nonstationary processes of pulsed laser polymerization (PLP). The new simulation tool applied systematically investigate how temperature gradients that develop in sample cell influence accuracy propagation rate coefficients, kp, determined by PLP-SEC method. Although center may increase more than 30 °C during pulsing bulk vinyl acetate (VAc), this does not greatly kp from cumulative polymer molar mass distribution...

Abstract The ring‐opening polymerization of glycidol at elevated temperatures is investigated. To improve the synthesis dendritic polyether polyols, experiments are carried out without initiator to identify influence thermal side reactions. This results in a step‐growth caused by spontaneous combination monomers. Kinetic parameters reactions estimated fitting simulated number‐ and weight‐average molecular weights experimental values measured different reaction times during polymerization....

The factors influencing the periodic structure in molar mass distributions (MMDs) generated pulsed-laser polymerization (PLP) experiments are investigated to extend range of operating conditions under which radical propagation rate coefficients (kp) can be reliably estimated. Specifically, it is shown how kp may determined well into corresponding so-called low and high termination limits. A new parameter x introduced provide a convenient measure when PLP pseudostationary approach (x ≤ 0.2) ≥...

Abstract Summary: Unexpected difficulties are encountered in the determination of propagation rate coefficients ( k p ) free radical polymerization alkyl acrylates by pulsed laser (PLP), mainly due to intramolecular transfer polymer. 1 This article is focused on role played high power these and possible reactions mid‐chain with residual oxygen. Removing oxygen simple bubbling nitrogen sufficient avoid alteration kinetics under PLP conditions. Moreover, no degradation polymer (or solvent) has...

A penultimate model of acrylate polymerization has been proposed to account for reduced reactivity radicals formed by monomer addition midchain radicals. New expressions derived rate, number-average degree and branching level are used a comparative analysis the terminal models. The also implemented into simulation program PREDICI conduct time dependencies conversion, cumulative number-degree levels calculated different calculations show that, depending on radical ratio s(i) concentrations,...