Determination of transfer to monomer in the vinyl chloride polymerization

Vidotto, G.; Crosato‐Arnaldi, A.; Talamini, G.

doi:10.1002/macp.1968.021140117

Cited by 38 publications

(6 citation statements)

References 12 publications

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“…This balances the low fractions of chains formed early in the process, thereby resulting in similar final molecular weights and molecular weight distributions for the chains formed under the conventional process. These results are consistent with research to the effect that the molecular weight of PVC is slightly affected by initiator concentration and is significantly affected by polymerization temperature . Figure compares the average molecular weight distributions of the final PVC produced by two processes.…”

Section: Resultssupporting

confidence: 89%

“…In general, in the suspension polymerization of vinyl chloride, the morphological properties of the PVC grains are governed by polymerization conditions such as the initiator addition method, polymerization temperature, quality of agitation, type and concentration of the suspending agents, the polymerization VCM/water ratio, monomer reflux conditions, and the conversion . The molecular weight (MW) and molecular weight distribution (MWD) of PVC resin are only governed by the polymerization temperature as a result of the great importance of chain transfer to monomer …”

Section: Introductionmentioning

confidence: 99%

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Continuous dosing of fast initiator during vinyl chloride suspension polymerization: Polymerization rate and PVC properties

Bijhanmanesh

Etesami

2016

J of Applied Polymer Sci

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Continuous dosing of a fast initiator during the suspension polymerization of vinyl chloride has been carried out in a pilot-scale reactor. The kinetics course of this polymerization and the particle features of the resulting grains were discussed and compared to the conventional polymerization with the same conversion and maximum reaction rate. It was found for the system used that a suitable dosage trajectory allows the reaction rate to remain constant during polymerization. This decreases the polymerization time up to 53% compared with the conventional suspension polymerization, while the molecular weight distribution and molecular weight of the final grains remained almost unchanged. SEM micrographs revealed that PVC grains prepared using this polymerization process had irregularly shaped, uneven particle surfaces and larger particle sizes. The grains also featured high porosity with loosely aggregated smaller primary particles that led to low levels of residual unreacted monomer. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44079.

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Continuous dosing of fast initiator during vinyl chloride suspension polymerization: Polymerization rate and PVC properties

Bijhanmanesh

Etesami

2016

J of Applied Polymer Sci

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“…. In addition, the average molecular weight of the PVC resin increased sharply before a conversion of 23%, after which the rate of increase slowed down . These observations may have been observed for two reasons.…”

Section: Resultsmentioning

confidence: 92%

The influence of two‐stage variable temperature suspension polymerization on polyvinyl chloride resin: The molecular chain segment structure and thermal stability

Geng

Wang

et al. 2018

Vinyl Additive Technology

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The suspension polymerization of polyvinyl chloride (PVC) was carried out at two different constant temperature conditions (52.5°C and 57.5°C) and at two‐stage variable temperature conditions (52.5–57.5°C). The molecular weight and molecular weight distribution were characterized by gel permeation chromatography (GPC). The unstable chlorine content, total double bond content, and conjugated diene content were explored via phenol substitution, catalytic bromine addition, and ultraviolet–visible spectroscopy (UV–Vis). pH meter and thermogravimetric analyzer (TGA) were used for the determination of the thermal stability. According to the results, due to the gradual consumption of the impurities and the effect of the local high temperature in the early stage of polymerization, which caused more molecular chain‐transfer and more structural defects, a large number of oligomers generated. A rapid increase in the molecular weight could be found until the conversion was close to 23%. A lower temperature should be conducive to reducing the structural defects in molecular segments. Based on these observations, we applied two‐stage variable temperature polymerization and compared the PVC resin at a similar molecular weight at a constant temperature of 56°C. The PVC resin produced by the two‐stage variable temperature polymerization process obtained a similar Polydispersity index (PDI), reduced the unstable chlorine content by 15.11%, reduced the total double bond structure content by 8.81%, reduced the conjugated diene structure content by 13.86%, and increased the thermal stability time by 13.91%, thereby improving the thermal stability of the PVC resin. J. VINYL ADDIT. TECHNOL., 25:E80–E87, 2019. © 2018 Society of Plastics Engineers

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“…Monomers may also bear abstractable atoms and are thus prone to chain transfer reactions. Some monomers such as vinyl acetate and vinyl chloride have quite high chain transfer to monomer (Ctrm) values . The chain transfer to monomer could also be responsible for the deviation of M n and Ð from their controlled values.…”

Section: Model Development and Simulationmentioning

confidence: 99%

Modeling and Experimentation of RAFT Solution Copolymerization of Styrene and Butyl Acrylate, Effect of Chain Transfer Reactions on Polymer Molecular Weight Distribution

Jiang

Wang

et al. 2017

Macro Reaction Engineering

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The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/mren.201700029. RAFT Solution CopolymerizationChain transfer reactions widely exist in the free radical polymerization and controlled radical polymerization, which can significantly influence polymer molecular weight and molecular weight distribution. In this work, the chain transfer reactions in modeling the reversible addition-fragmentation transfer (RAFT) solution copolymerization are included and the effects of chain transfer rate constant, monomer concentration, and comonomer ratio on the polymerization kinetics and polymer molecular weight development are investigated. The model is verified with the experimental RAFT solution copolymerization of styrene and butyl acrylate, with good agreements achieved. This work has demonstrated that the chain transfer reactions to monomer and solvent can have significant impacts on the number-average molecular weight (M n ) and dispersity (Ð).

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Determination of transfer to monomer in the vinyl chloride polymerization

Cited by 38 publications

References 12 publications

Continuous dosing of fast initiator during vinyl chloride suspension polymerization: Polymerization rate and PVC properties

Continuous dosing of fast initiator during vinyl chloride suspension polymerization: Polymerization rate and PVC properties

The influence of two‐stage variable temperature suspension polymerization on polyvinyl chloride resin: The molecular chain segment structure and thermal stability

Modeling and Experimentation of RAFT Solution Copolymerization of Styrene and Butyl Acrylate, Effect of Chain Transfer Reactions on Polymer Molecular Weight Distribution

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