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Free Radical Chain Polymerization: 10: ..

Ionic polymerizations are more difficult to carry out on anindustrial scale than free-radical polymerizations. Ionicpolymerization is therefore only used for monomers that don'tpolymerize by the free-radical mechanism or to prepare polymerswith a regular structure.

prepared with methyl methacrylate and styrene onto PVC using atom transfer radical ..

In a step-reaction polymerization reaction, sometimes called condensation polymerization, the polymer chains grow by reactions that occur between two molecular species. An example is the polymerization reaction involving terephthalic acid and ethylene glycol, both of which are bifunctional.

Radical block polymerization of vinyl chloride

Radical Block Polymerization of Vinyl Chloride

Using the PVC as a macroinitiator, grafting polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA) in THF at 50℃ was started, and PVC-based graft copolymer (PVC-g-PDMAEMA) was synthesized.

AB - A series of amphiphilic graft copolymers consisting of poly(vinyl chloride) (PVC) main chains and poly(vinyl pyrrolidone) (PVP) side chains, i.e. PVC-g-PVP, was synthesized via atom transfer radical polymerization (ATRP), as confirmed by 1H NMR, FT-IR spectroscopy, and gel permeation chromatography (GPC). Transmission electron microscope (TEM) and small angle X-ray scattering (SAXS) analysis revealed the microphase-separated structure of PVC-g-PVP and the domain spacing increased from 21.4 to 23.9nm with increasing grafting degree. All the membranes exhibited completely amorphous structure and high Young's modulus and tensile strength, as revealed by wide angle X-ray scattering (WAXS) and universal testing machine (UTM). Permeation experimental results using a CO 2/N 2 (50/50) mixture indicated that as an amount of PVP in a copolymer increased, CO 2 permeability increased without the sacrifice of selectivity. For example, the CO 2 permeability of PVC-g-PVP with 36wt% of PVP at 35°C was about four times higher than that of the pristine PVC membrane. This improvement resulted from the increase of diffusivity due to the disruption of chain packing in PVC by the grafting of PVP, as confirmed by WAXS analysis.

Polystyrene prepared by free-radical polymerization is ..

N2 - A series of amphiphilic graft copolymers consisting of poly(vinyl chloride) (PVC) main chains and poly(vinyl pyrrolidone) (PVP) side chains, i.e. PVC-g-PVP, was synthesized via atom transfer radical polymerization (ATRP), as confirmed by 1H NMR, FT-IR spectroscopy, and gel permeation chromatography (GPC). Transmission electron microscope (TEM) and small angle X-ray scattering (SAXS) analysis revealed the microphase-separated structure of PVC-g-PVP and the domain spacing increased from 21.4 to 23.9nm with increasing grafting degree. All the membranes exhibited completely amorphous structure and high Young's modulus and tensile strength, as revealed by wide angle X-ray scattering (WAXS) and universal testing machine (UTM). Permeation experimental results using a CO 2/N 2 (50/50) mixture indicated that as an amount of PVP in a copolymer increased, CO 2 permeability increased without the sacrifice of selectivity. For example, the CO 2 permeability of PVC-g-PVP with 36wt% of PVP at 35°C was about four times higher than that of the pristine PVC membrane. This improvement resulted from the increase of diffusivity due to the disruption of chain packing in PVC by the grafting of PVP, as confirmed by WAXS analysis.

A series of amphiphilic graft copolymers consisting of poly(vinyl chloride) (PVC) main chains and poly(vinyl pyrrolidone) (PVP) side chains, i.e. PVC-g-PVP, was synthesized via atom transfer radical polymerization (ATRP), as confirmed by 1H NMR, FT-IR spectroscopy, and gel permeation chromatography (GPC). Transmission electron microscope (TEM) and small angle X-ray scattering (SAXS) analysis revealed the microphase-separated structure of PVC-g-PVP and the domain spacing increased from 21.4 to 23.9nm with increasing grafting degree. All the membranes exhibited completely amorphous structure and high Young's modulus and tensile strength, as revealed by wide angle X-ray scattering (WAXS) and universal testing machine (UTM). Permeation experimental results using a CO 2/N 2 (50/50) mixture indicated that as an amount of PVP in a copolymer increased, CO 2 permeability increased without the sacrifice of selectivity. For example, the CO 2 permeability of PVC-g-PVP with 36wt% of PVP at 35°C was about four times higher than that of the pristine PVC membrane. This improvement resulted from the increase of diffusivity due to the disruption of chain packing in PVC by the grafting of PVP, as confirmed by WAXS analysis.

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SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION …

Because the intermediates involved in ionic polymerizationreactions can't combine with one another, chain termination onlyoccurs when the growing chain reacts with impurities or reagentsthat can be specifically added to control the rate of chaingrowth. It is therefore easier to control the average molecularweight of the product of ionic polymerization reactions.

is produced by the radical polymerization of ..

The initiation step of ionic polymerization reactions has amuch smaller activation energy than the equivalent step forfree-radical polymerizations. As a result, ionic polymerizationreactions are relatively insensitive to temperature, and can berun at temperatures as low as -70°C. Ionic polymerizationtherefore tends to produce a more regular polymer, with lessbranching along the backbone, and more controlled tacticity.

Polymer Synthesis -Free Radical Polymerization

Polyesters are condensation polymers, which contain fewer atoms within the polymer repeat unit than the reactants because of the formation of byproducts, such as H2O or NH3, during the polymerization reaction. Most synthetic fibers are condensation polymers.

PDF Downloads : Oriental Journal of Chemistry

2 PVC Manufacture Technology
2.1 Monomer
2.2 Basic Steps of Radical Polymerization
2.2.1 Initiation
2.2.2 Propagation
2.2.3 Termination
2.2.4 Chain transfer to monomer
2.3 Polymerization technology
2.3.1 Suspension
2.3.2 Paste resin manufacturing processes
2.3.3 Bulk
2.3.4 Solution
2.4 Polymerization conditions and PVC properties
References

3 PVC Morphology
3.1. Molecular weight of polymer (chain length)
3.2. Configuration and conformation
3.3. Chain folds
3.4. Chain thickness
3.5 Entanglements
3.6 Crystalline structure
3.7 Grain morphology
3.7.1 Stages of morphology development during manufacture
3.7.1.1 Suspension polymerization
3.7.1.2 Paste grades manufacture
3.7.1.3 Bulk polymerization
3.7.2 Effect of morphology on degradation
References

4 Principles of Thermal Degradation
4.1 The reasons for polymer instability
4.1.1 Structural defects
4.1.1.1 Branches
4.1.1.2 Tertiary chlorine
4.1.1.3 Unstaturations
4.1.1.4 Oxygen containing groups
4.1.1.5 Head-to-head structures
4.1.1.6 Morphology
4.1.2 Polymerization residue
4.1.2.1 Initiator rests
4.1.2.2 Transfer agent rests
4.1.2.3 Polymerization additives
4.1.3 Metal derivatives
4.1.3.1 Metal chlorides
4.1.3.2 Copper and its oxide
4.1.4 Hydrogen chloride 14
4.1.5 Impurities
4.1.6 Shear
4.1.7 Temperature
4.1.8 Surrounding atmosphere
4.1.9 Additives
4.2 Mechanisms of thermal degradation
4.2.1 Molecular mechanism
4.2.2 Amer-Shapiro mechanism
4.2.3 Six-center concerted mechanism
4.2.4 Activation enthalpy
4.2.5 Radical-chain theory
4.2.6 Ionic
4.2.7 Polaron
4.2.8 Degenerated branching
4.2.9 Transition state theory
4.2.10 Recapitulation
4.3 Kinetics
4.3.1 Initiation
4.3.2 Propagation
4.3.3 Termination
4.4 Results of thermal degradation
4.4.1 Volatiles
4.4.2 Weight loss
4.4.3 Char formation
4.4.4 Ash content
4.4.5 Thermal lifetime
4.4.6 Optical properties
4.4.6.1 Color change
4.4.6.2 Extinction coefficient
4.4.6.3 Absorbance
4.4.7 Molecular weight
4.4.8 Mechanical properties
4.4.9 Electric properties
4.5 Effect of additives
4.5.1 Blend polymers
4.5.1.1 ABS
4.5.1.2 Chlorinated polyethylene, CPE
4.5.1.3 Epoxidized butadiene/styrene block copolymer
4.5.1.4 Epoxidized natural rubber
4.5.1.5 Ethylene vinyl acetate, EVA
4.5.1.6 High impact polystyrene, HIPS
4.5.1.7 Methylmethacrylate-butadiene-styrene
4.5.1.8 Nitrile rubber, NBR
4.5.1.9 Oxidized polyethylene, OPE
4.5.1.10 Polyacrylate
4.5.1.11 Polyacrylonitrile
4.5.1.12 Polyamide
4.5.1.13 Polyaniline, PANI
4.5.1.13 Polycarbonate, PC
4.5.1.14 Polyethylene, PE
4.5.1.15 Poly(methyl methacrylate), PMMA
4.5.1.16 Poly(N-vinyl-2-pyrrolidone), PVP
4.5.1.17 Polysiloxane
4.5.1.18 Polystyrene, PS
4.5.1.19 Polythiophene
4.5.1.20 Polyurethane
4.5.1.21 Poly(vinyl acetate), PVAc
4.5.1.22 Poly(vinyl alcohol), PVA
4.5.1.23 Poly(vinyl butyral), PVB
4.5.1.24 SAN
4.5.2 Antiblocking
4.5.3 Antistatics agents
4.5.4 Biocides and fungicides
4.5.5 Blowing agents
4.5.6 Fillers
4.5.7 Flame retardants
4.5.8 Impact modifiers
4.5.9 Lubricants
4.5.10 Pigments
4.5.11 Plasticizers
4.5.12 Process aids
4.5.13 Solvents
4.5.14 Stabilizers
References

5 Principles of UV Degradation
5.1 Reasons for polymer instability
5.1.1 Radiative energy
5.1.2 Radiation intensity
5.1.3 Radiation incidence
5.1.4 Absorption of radiation by materials
5.1.5 Bond structure
5.1.6 Thermal history
5.1.7 Photosensitizers
5.1.8 Wavelength sensitivity
5.1.9 Thermal variability
5.1.10 Pollutants
5.1.11 Laboratory degradation conditions
5.2 Mechanisms of degradation
5.2.1 Radical mechanism
5.2.1.1 Photooxidation mechanism
5.2.1.2 Mechanistic scheme
5.2.1.3 Conformational mechanism
5.2.1.4 Electronic-to-vibrational energy transfer
5.2.1.5 Other contributions to the mechanism of photodegradation
5.3 Kinetics
5.3.1 Initiation
5.3.2 Propagation
5.3.3 Termination
5.4 Results of UV degradation
5.4.1 Photodiscoloration
5.4.2 Mechanical properties
5.4.3 Other properties
5.5 Effect of additives
5.5.1 Biocides and fungicides
5.5.2 Fillers
5.5.3 Flame retardants
5.5.4 Impact modifiers
5.5.5 Lubricants
5.5.6 Pigments and colorants
5.5.6.1 Titanium dioxide
5.5.6.2 Zinc oxide
5.5.6.3 Iron-containing pigments
5.5.7 Plasticizers
5.5.8 Polymer blends
5.5.9 Solvents
5.5.10 Stabilizers
References

6 Principles of Degradation by γ-Radiation
6.1 The reasons for polymer instability
6.2 Mechanisms
6.3 Kinetics
6.4 Results
6.5 Effect of additives
6.5.1 Plasticizers
6.5.2 Fillers
6.5.3 Stabilizers
References

7 Degradation by Other Forms of Radiation
7.1 Argon plasma
7.2 b-radiation (electron beam)
7.3 Corona discharge
7.4 Ion (proton) beam
7.5 Laser
7.6 Metallization
7.7 Microwave
7.8 Neutron irradiation
7.9 Oxygen plasma
7.10 X-rays
7.11 Ultrasonic
References
8 Mechanodegradation
References

9 Chemical Degradation

9.1 methods of chemical dehydrochlorination
9.2. Kinetics and mechanisms of reaction
References

10 Analytical Methods
10.1 Heat stability test
10.1.1 Sample preparation
10.1.2 Kinetic studies of dehydrochlorination
10.1.3 Dehydrochlorination rate and optical changes
10.1.4 Degradation in solution
10.2 Thermogravimetric analysis
10.2.1 Differential scanning calorimetry, DSC
10.2.2 Mass loss
10.3 Combustion
10.4 Optical properties
10.5 Spectroscopic methods
10.5.1 Atomic absorption, AAS
10.5.2 Auger
10.5.3 Electron spin resonance, ESR
10.5.4 Fourier transform infrared, FTIR
10.5.5 Laser photopyroelectric effect spectrometry
10.5.6 Mass, MS
10.5.7 Mossbauer
10.5.8 Near infrared, NIR
10.5.9 Nuclear magnetic resonance, NMR
10.5.10 Positron annihilation lifetime spectroscopy, PAS
10.5.11 Raman
10.5.12 Time-of-flight secondary ion mass spectrometry, ToF-SIMS
10.5.13 X-ray analysis
10.5.13.1 Small angle light scattering, SAXS
10.5.13.2 Wide angle light scattering, WAXS or WAXD
10.5.14 X-ray photoelectron spectroscopy, XPS
10.5.15 UV-visible
10.6 Chromatographic methods
10.1 Gas chromatography
10.6.2 Liquid chromatography
10.7 Mechanical properties
10.8 Other essential methods of testing
10.8.1 Action spectrum
10.8.2 Coulter counter
10.8.3 Gel content
10.8.4 Ozonolysis
10.8.5 Peroxide titration
10.8.6 Rheological studies
10.9 International standards
References

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