Studies of Nascent Polymer Morphology in Inertially Suspended Vinyl Chloride Drops

Zichy, E.L.

doi:10.1080/00222337708061321

Cited by 33 publications

(11 citation statements)

References 5 publications

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“…This has been brought about by a number of factors, one of the most important being the toxicity of VCM, which has led to a reduction in the unreacted monomer. Several technological improvements have been advanced to meet this requirement, such as using composite suspending agents and adding oil‐soluble surfactants to the VCM suspension process to produce higher porosity resins from which it is easier to strip unreacted VCM 1, 3, 19–22. Other ways should be developed to meet this requirement.…”

Section: Introductionmentioning

confidence: 99%

Particle features of poly(vinyl chloride) resins prepared by a new heterogeneous polymerization process

Bao

Brooks

2003

J of Applied Polymer Sci

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ABSTRACT:The heterogeneous polymerization of vinyl chloride monomer (VCM), with n-butane as the reaction medium, was used to prepare poly(vinyl chloride) (PVC) resins. The particle features of the resulting resins and the particle formation mechanism of the polymerization process were investigated. The PVC resins prepared by the new polymerization process had a volume-average particle size comparable to that of suspension PVC resins and a lower number-average particle size. From scanning electron micrographs, it could be seen that the new PVC resins had a regular particle shape and a smooth surface with no obvious skin. They also had a high porosity. The new PVC resins were composed of individual and loosely aggregated primary particles. The diameter of the primary particles in the top layer of the grains was smaller than that of the primary particles in the center part of the grains. On the basis of the particle features of these PVC resins, a particle formation mechanism for the new polymerization process was proposed. PVC chains precipitate from a VCM/n-butane mixed medium to form primary aggregates at a very low conversion, and the primary aggregates of the PVC chains aggregate to form primary particles, which further aggregate to form grains. The primary particles and grains grow by the capture of newly formed PVC chains and their primary aggregates and by polymerization occurring inside the aggregates.

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Section: Introductionmentioning

confidence: 99%

Particle features of poly(vinyl chloride) resins prepared by a new heterogeneous polymerization process

Bao

Brooks

2003

J of Applied Polymer Sci

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“…When the pericellular membrane holes become sufficiently tight, and these short chains encounter progressively more difficulties in joining the polymerization media inside the particles, and therefore, stay on the interface and continue growing. Moreover, higher temperature at low conversions in nonisothermal conditions increases the dispersion and diffusion rate of the initiator into the monomer droplet and makes initiation occur more homogeneously throughout the volume of the droplet rather than at the interfacial skin, once again resulting in a more porous membrane .…”

Section: Resultsmentioning

confidence: 99%

Investigation of the effects of nonisothermal suspension polymerization of vinyl chloride on resin properties

Darvishi

Esfahany

Bagheri

2015

Vinyl Additive Technology

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Molecular and morphological properties of suspension poly(vinyl chloride) produced by nonisothermal polymerization was experimentally investigated in a pilot-scale reactor. Although molecular weight and polydispersity index of the nonisothermally produced poly(vinyl chloride) is almost the same as the equivalent isothermal polymerization, there are differences in morphological characteristics. The cold plasticizer absorption of the resin produced nonisothermally is greater than that of the equivalent isothermal product. Scanning electron microscopy showed that nonisothermally produced particles are more regularly shaped, with a smoother surface, and had greater porosity compared with the product of isothermal polymerization reaction. Applying temperature trajectory produces particles with slightly wider particle size distribution relative to the particles produced isothermally. The evolution of particles with conversion is characterized by processing images obtained by scanning electron microscope. Applying a variable temperature trajectory accelerates the formation of a three-dimensional skeleton of primary particles relative to the isothermally produced particles. J. VINYL ADDIT. TECHNOL., 23:267-274, 2017.

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“…Several process variables, such as polymerization temperature, agitation rate, type, concentration of stabilizers, and so on, involved in the development of the morphology of suspension-PVC (S-PVC) have been found to have a significant influence on the internal structures in S-PVC [1,[8][9][10][11][12][13][14][15][16][17][18][19]. Although a significant amount of research has been done, the mechanism by which morphology arises in S-PVC is not completely understood.…”

Section: Introductionmentioning

confidence: 99%

“…Next, three-dimensional networks with interstitial space are formed from these primary particles through fusion or interknitting over a range of monomer conversions. Finally, the formation of the polymer networks grows in number and in size until the drop volume is totally filled with polymer agglomerates [1,3,[8][9][10][11][12][13][14][15][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Mechanistic investigation of nonisothermal suspension polymerization of vinyl chloride

Darvishi

Esfahany

Bagheri

2015

Vinyl Additive Technology

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Vinyl chloride suspension polymerization using different temperature trajectories was carried out in a pilot scale batch reactor. Detailed understanding of the conversion at which the primary particles become motionless (Xm) and the key effects of Xm on morphology development of PVC grains were provided. Motionless conversion is estimated for poly(vinyl chloride) (PVC) grains prepared with different temperature trajectories by cold plasticizer absorption measurements. The porosity of PVC grains (prepared isothermally and nonisothermally) shows a maximum at a certain conversion that is considered motionless conversion. With increasing monomer conversion, the cold plasticizer uptake decreases dramatically with conversions greater than motionless conversion until the monomer phase is completely exhausted (Xf) and continues to slightly decrease after Xf. The decrease in cold plasticizer absorption is more pronounced for PVC grains produced nonisothermally by lower initial temperature. The results obtained by scanning electron microscopy and Brabender® plastography showed that the changes in internal structure and fusion behavior of PVC grains after Xm would be much lower when early aggregates of primary particles are formed. Scanning electron microscopy photographs indicate that applying the variable temperature with negative slope accelerates networking between the primary particles inside the polymerizing monomer droplets. The Brabender® plastograph measurements indicate a lower time and temperature of fusion and a higher degree of gelation for nonisothermally produced resin in which the temperature trajectory follows a greater negative slope. J. VINYL ADDIT. TECHNOL., 24:84–92, 2018. © 2015 Society of Plastics Engineers

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Studies of Nascent Polymer Morphology in Inertially Suspended Vinyl Chloride Drops

Cited by 33 publications

References 5 publications

Particle features of poly(vinyl chloride) resins prepared by a new heterogeneous polymerization process

Particle features of poly(vinyl chloride) resins prepared by a new heterogeneous polymerization process

Investigation of the effects of nonisothermal suspension polymerization of vinyl chloride on resin properties

Mechanistic investigation of nonisothermal suspension polymerization of vinyl chloride

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