Free Radical Chain Polymerization (Addition Polymerization)

Mixtures of ethane and ethylene have been pyrolyzed in the temperature range 563–600 °C and at pressures from 30–60 cm. The products were similar to those obtained from the pyrolysis of ethylene by itself, described m Part I, with a marked increase in the yields of the saturated products. The initial rates of product formation and the dependence of these rates on the concentration of ethane suggest that the initiation step is the same as that proposed in the pyrolysis of ethylene alone, viz.[Formula: see text]and that the reaction[Formula: see text]is not an important source of radicals. A simplified mechanism is outlined to account for the main effects of ethane on the free radical chain polymerization.

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Solvent Effect on Free-Radical Chain Polymerization. 7. Kinetical Analysis of the Binary System Methyl Methacrylate/N-Vinylpyrrolidone in Bulk and in Model Solvents in Terms of the Reactant-Solvent Complex Model

Macromolecules ◽

10.1021/ma00120a003 ◽

1995 ◽

Vol 28 (16) ◽

pp. 5411-5418 ◽

Cited By ~ 13

Author(s):

Wojciech Krzysztof Czerwinski

Keyword(s):

Free Radical ◽

Binary System ◽

Methyl Methacrylate ◽

Solvent Effect ◽

Complex Model ◽

Radical Chain ◽

Chain Polymerization ◽

Solvent Complex

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The Photoinitiator Lithium Phenyl (2,4,6-Trimethylbenzoyl) Phosphinate with Exposure to 405 nm Light Is Cytotoxic to Mammalian Cells but Not Mutagenic in Bacterial Reverse Mutation Assays

Polymers ◽

10.3390/polym12071489 ◽

2020 ◽

Vol 12 (7) ◽

pp. 1489

Author(s):

Alexander K. Nguyen ◽

Peter L. Goering ◽

Rosalie K. Elespuru ◽

Srilekha Sarkar Das ◽

Roger J. Narayan

Keyword(s):

Free Radicals ◽

Free Radical ◽

Mammalian Cells ◽

Light Exposure ◽

Collecting Duct ◽

Radical Chain ◽

Reverse Mutation ◽

E Coli ◽

A Cell ◽

Chain Polymerization

Lithium phenyl (2,4,6-trimethylbenzoyl) phosphinate (LAP) is a free radical photo-initiator used to initiate free radical chain polymerization upon light exposure, and is combined with gelatin methacryloyl (GelMA) to produce a photopolymer used in bioprinting. The free radicals produced under bioprinting conditions are potentially cytotoxic and mutagenic. Since these photo-generated free radicals are highly-reactive but short-lived, toxicity assessments should be conducted with light exposure. In this study, photorheology determined that 10 min exposure to 9.6 mW/cm2 405 nm light from an LED light source fully crosslinked 10 wt % GelMA with >3.4 mmol/L LAP, conditions that were used for subsequent cytotoxicity and mutagenicity assessments. These conditions were cytotoxic to M-1 mouse kidney collecting duct cells, a cell type susceptible to lithium toxicity. Exposure to ≤17 mmol/L (0.5 wt %) LAP without light was not cytotoxic; however, concurrent exposure to ≥3.4 mmol/L LAP and light was cytotoxic. No condition of LAP and/or light exposure evaluated was mutagenic in bacterial reverse mutation assays using S. typhimurium strains TA98, TA100 and E. coli WP2 uvrA. These data indicate that the combination of LAP and free radicals generated from photo-excited LAP is cytotoxic, but mutagenicity was not observed in bacteria under typical bioprinting conditions.

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Kinetics of the thermal reactions of ethylene. Part I

Canadian Journal of Chemistry ◽

10.1139/v68-394 ◽

1968 ◽

Vol 46 (14) ◽

pp. 2415-2426 ◽

Cited By ~ 24

Author(s):

M. L. Boyd ◽

T-M. Wu ◽

M. H. Back

Keyword(s):

Activation Energy ◽

Molecular Weight ◽

Free Radical ◽

Induction Period ◽

Pressure Range ◽

Kcal Mole ◽

Radical Chain ◽

Thermal Reactions ◽

Chain Polymerization ◽

Kinetics Of

The pyrolysis of ethylene has been studied in the temperature range 500–600 °C and the pressure range 15–60 cm. The main products were ethane, propylene, butene, butadiene, and a polymer of molecular weight corresponding to C8 or higher. Small amounts of methane, butane, unsaturated C5, unsaturated C6, and benzene were also measured. Of the main products, propylene, butene, and butadiene showed an induction period, as long as several minutes at the lowest temperature. The order with respect to ethylene of ethane, propylene, and butene was close to two and the activation energy of the rates was approximately 40 kcal/mole. The results have been interpreted in terms of a free radical chain polymerization. It is suggested that the polymer formed is unstable and decomposes to yield the products for which an induction period was observed.

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