scholarly journals Insights on the Atmospheric-Pressure Plasma-Induced Free-Radical Polymerization of Allyl Ether Cyclic Carbonate Liquid Layers

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2856
Author(s):  
Edyta M. Niemczyk ◽  
Alvaro Gomez-Lopez ◽  
Jean R. N. Haler ◽  
Gilles Frache ◽  
Haritz Sardon ◽  
...  
Keyword(s):  
Free Radical ◽  
Radical Polymerization ◽  
Atmospheric Pressure ◽  
High Resolution Mass Spectrometry ◽  
Free Radical Polymerization ◽  
Monomer Conversion ◽  
Cyclic Carbonate ◽  
Allyl Ether ◽  
Chain Growth ◽  
Plasma Exposure

Plasma-induced free-radical polymerizations rely on the formation of radical species to initiate polymerization, leading to some extent of monomer fragmentation. In this work, the plasma-induced polymerization of an allyl ether-substituted six-membered cyclic carbonate (A6CC) is demonstrated and emphasizes the retention of the cyclic carbonate moieties. Taking advantage of the low polymerization tendency of allyl monomers, the characterization of the oligomeric species is studied to obtain insights into the effect of plasma exposure on inducing free-radical polymerization. In less than 5 min of plasma exposure, a monomer conversion close to 90% is obtained. The molecular analysis of the oligomers by gel permeation chromatography coupled with high-resolution mass spectrometry (GPC-HRMS) further confirms the high preservation of the cyclic structure and, based on the detected end groups, points to hydrogen abstraction as the main contributor to the initiation and termination of polymer chain growth. These results demonstrate that the elaboration of surfaces functionalized with cyclic carbonates could be readily elaborated by atmospheric-pressure plasmas, for instance, by copolymerization.

Modelling the Complete Molecular Weight Distribution in Chain Growth Polymerizations

2016 ◽  
Vol 1819 ◽  
Author(s):  
Ramiro Infante-Martínez ◽  
Enrique Saldívar-Guerra ◽  
Odilia Pérez-Camacho ◽  
Maricela García-Zamora ◽  
Víctor Comparán-Padilla
Keyword(s):  
Molecular Weight ◽  
Free Radical ◽  
Radical Polymerization ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Chain Transfer ◽  
Free Radical Polymerization ◽  
Experimental Program ◽  
Chain Growth ◽  
Coordination Polymerization

ABSTRACTThis work shows the development of several models for chain-growth polymerizations that admit the direct calculation of the complete molecular weight distribution of the polymer. The direct and complete calculation implies that no statistical mean values are employed as in the moments method neither numerical approximations like in the minimum-squared based methods. The free radical polymerization of ethylene (LDPE) and the coordination via metallocenes polymerization of ethylene (HDPE) are taken as examples for analysis.In the free radical polymerization case, the conventional scheme for chain-growth polymerization is adopted, with steps for initiation, propagation, chain transfer to small species and the additional step of chain transfer to dead chains [1]. The kinetic parameter are obtained from the open literature. Two kind of reactors were modelled: batch and continuous stirred tank reactor. For this last case, a simulation strategy was considered in which the run started from an initial known population of dead chains. Results show that typical non-linear polymerization profiles for the molecular weight distribution are obtained. For the coordination polymerization of ethylene via metalocenes, the standard coordination model was employed [2]. A two-site catalyst was considered and kinetic parameters reported in the open literature were used. For this study an experimental program in a lab-scale reactor was undertaken in order to obtain modelling data [3]. Results show that the standard model adequately reproduces the experimental data in the kinetic and molecular attributes of the polymer.

Effects of initiator loss by chain transfer in free-radical polymerization using batch operations

1992 ◽  
Vol 437 (1901) ◽  
pp. 489-499
Keyword(s):  
Free Radical ◽  
Molecular Mass ◽  
Radical Polymerization ◽  
Chain Transfer ◽  
Batch Reactor ◽  
Monomer Concentration ◽  
Free Radical Polymerization ◽  
Monomer Conversion ◽  
Degree Of Polymerization ◽  
Initial Monomer

In the free-radical polymerization of vinyl monomers, initiator can be lost by chain transfer. This loss affects the monomer conversion with time in a batch reactor and can influence the expected molecular mass of the polymer as the reaction proceeds. Expressions are developed which allow these effects to be quantified. Examples indicate when these effects are important. The instantaneous number-average degree of polymerization passes through a minimum as the initiator concentration is increased. The location of this minimum depends on the importance of initiator loss by chain transfer. Initial monomer concentration affects the absolute value of molecular mass but has little influence on the relative effects of initiator loss by chain transfer.

scholarly journals Direct and inverse neural network modeling in free radical polymerization

2004 ◽  
Vol 2 (1) ◽  
pp. 113-140 ◽  
Author(s):  
Silvia Curteanu
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Free Radical ◽  
Radical Polymerization ◽  
Network Modeling ◽  
Free Radical Polymerization ◽  
Monomer Conversion ◽  
Polymerization Reaction ◽  
Neural Network Modeling ◽  
Hidden Neurons

AbstractThe first part of this paper reviews of the most important aspects regarding the use of neural networks in the polymerization reaction engineering. Then, direct and inverse neural network modeling of the batch, bulk free radical polymerization of methyl methacrylate is performed. To obtain monomer conversion, number and weight average molecular weights, and mass reaction viscosity, separate neural networks and, a network with multiple outputs were built (direct neural network modeling). The inverse neural network modeling gives the reaction conditions (temperature and initial initiator concentration) that assure certain values of conversion and polymerization degree at the end of the reaction. Each network is a multi-layer perceptron with one or two hidden layers and a different number of hidden neurons. The best topology correlates with the smallest error at the end of the training phase. The possibility of obtaining accurate results is demonstrated with a relatively simple architecture of the networks. Two types of neural network modeling, direct and inverse, represent possible alternatives to classical procedures of modeling and optimization, each producing accurate results and having simple methodologies.

scholarly journals Tris-imidazolinium-based porous poly(ionic liquid)s as an efficient catalyst for decarboxylation of cyclic carbonate to epoxide

RSC Advances ◽  
2021 ◽  
Vol 11 (23) ◽  
pp. 14193-14202
Author(s):  
Yang Li ◽  
Liguo Wang ◽  
Yan Cao ◽  
Shuang Xu ◽  
Peng He ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Free Radical ◽  
Radical Polymerization ◽  
Free Radical Polymerization ◽  
Catalytic Performance ◽  
Cyclic Carbonate ◽  
Efficient Catalyst ◽  
Poly Ionic Liquid ◽  
Porous Poly

The tris-imidazolium-based porous poly(ionic liquid)s with plentiful ionic sites prepared by free-radical polymerization exhibited superior catalytic performance toward the heterogeneous conversion of butylene carbonate to butylene oxide.

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