Reactions between Peroxide and Polydiolefins

1965 ◽  
Vol 38 (3) ◽  
pp. 560-572 ◽  
Author(s):  
B. M. E. van der Hoff
Keyword(s):  
Main Chain ◽  
Hydrogen Abstraction ◽  
Reaction Scheme ◽  
Infrared Analysis ◽  
Double Bonds ◽  
Peroxide Values ◽  
Experimental Relation ◽  
Antioxidant Concentration

Abstract Reactions of cumyl peroxide with polyisoprenes and polybutadienes are compared. Hydrogen abstraction from polyisoprenes and recombination of polymer radicals yield a network with crosslink concentration equal to that of decomposed peroxide. The concentration of crosslinks in polybutadiene networks is much greater than that of decomposed peroxide. Values of the ratio of these two concentrations as high as 50 have been calculated from swelling measurements of the vulcanizates. The polybutadienyl radical attacks double bonds in the polymer; thus crosslinks are formed by propagation. Infrared analysis shows that propagation proceeds via unsaturation in the main chain as well as via double bonds of vinyl side groups. The experimental relation between crosslink concentration and antioxidant concentration is consistent with a reaction scheme based on termination of polymer radicals by antioxidant only.

On the Mechanism of Radical Polymerization of Methyl Methacrylate with Dithiobenzoic Acid as Mediator

2006 ◽  
Vol 59 (8) ◽  
pp. 549 ◽  
Author(s):  
Duc Hung Nguyen ◽  
Philipp Vana
Keyword(s):  
Methyl Methacrylate ◽  
Induction Period ◽  
Hydrogen Abstraction ◽  
Ester Group ◽  
Reaction Scheme ◽  
Ionization Mass ◽  
Controlled Polymerization ◽  
Induction Periods ◽  
Methyl Methacrylate Polymerization ◽  
Raft Agent

Dithiobenzoic acid (DTBA) induces controlled polymerization behaviour in methyl methacrylate polymerization at 60°C, accompanied by a pronounced induction period of several hours. DTBA is partially transformed during this induction period into a dithioester with a tertiary ester group moiety, which constitutes an efficient reversible addition–fragmentation chain transfer (RAFT) agent. The transformation reaction is proposed to proceed via a hydrogen abstraction from DTBA by radicals and subsequent termination of the formed phenylcarbonothioylsulfanyl radical with propagating radicals. The proposed reaction scheme was implemented into a computer model, by which the rate coefficient of the hydrogen abstraction from DTBA and of the reinitiation of the intermediate phenylcarbonothioylsulfanyl radical was estimated. The model is in agreement with all of the species observable by electrospray ionization mass spectrometry, with the extent of the experimental induction periods, and with the absolute concentrations of dithioesters that act as efficient RAFT agents during the polymerization. A protocol that uses a cocktail of initiators is introduced, by which the induction period in DTBA-mediated polymerization is effectively eliminated.

Thermomechanical properties of monodomain nematic main-chain liquid crystal elastomers

Soft Matter ◽  
2018 ◽  
Vol 14 (29) ◽  
pp. 6024-6036 ◽  
Author(s):  
Daniel R. Merkel ◽  
Nicholas A. Traugutt ◽  
Rayshan Visvanathan ◽  
Christopher M. Yakacki ◽  
Carl P. Frick
Keyword(s):  
Liquid Crystal ◽  
Main Chain ◽  
Reaction Scheme ◽  
Thermomechanical Properties ◽  
Two Stage ◽  
Liquid Crystal Elastomers

Actuation temperature was controlled without influencing total actuation performance in liquid crystal elastomers fabricated by a two-stage reaction scheme.

Study of the thermodynamic flexibility of macromolecules with double bonds in the main chain. Continuum model

1986 ◽  
Vol 28 (8) ◽  
pp. 1891-1901 ◽  
Author(s):  
A.L. Rabinovich ◽  
V.G. Dashevskii ◽  
P.O. Ripatti
Keyword(s):  
Continuum Model ◽  
Main Chain ◽  
Double Bonds

The Chemistry of 5-Oxodihydroisoxazoles. XIII. Reactions of the Imino Carbene Derived From Photolysis of Ethyl 5-Oxo-2-phenyl-2,5-dihydroisoxazole-4-carboxylate

1995 ◽  
Vol 48 (3) ◽  
pp. 567 ◽  
Author(s):  
KH Ang ◽  
RH Prager ◽  
CM Williams
Keyword(s):  
Hydrogen Abstraction ◽  
Double Bonds

Photolysis of ethyl 5-oxo-2-phenyl-2,5-dihydroisoxazole-4-carboxylate at 300 nm in acetonitrile gives a carbene which is captured efficiently by bromide, chloride, acetate and cyanate, and less efficiently by iodide, thiocyanate, cyclohexene and tetrahydrofuran. No hydrogen abstraction or reaction with double bonds was evident.

The Rate-Constant of the Reaction of Hydroxyl Radicals With Methanol, Ethanol and (D3)Methanol

1986 ◽  
Vol 39 (11) ◽  
pp. 1775 ◽  
Author(s):  
PG Greenhill ◽  
BV Ogrady
Keyword(s):  
Hydroxyl Radicals ◽  
Rate Constant ◽  
Flash Photolysis ◽  
Hydrogen Abstraction ◽  
Reaction Scheme ◽  
Resonance Absorption ◽  
Rate Coefficients ◽  
Secondary Reactions ◽  
Temperature Ranges ◽  
Predominant Process

The rate coefficients for hydrogen abstraction by hydroxyl radicals from methanol and ethanol have been determined in the temperature ranges 260-803 K and 255-459 K respectively. Flash photolysis combined with resonance absorption detection of OH was used to obtain results which may be described by the Arrhenius expressions:   Methanol ��� k(T) = (8.0�1.9)×10-12 exp[-(664�88)K/T]cm3 s-1 ������� (1)   Ethanol ���� k(T) = (1.25�0.24)×10-11 exp[-(360�52)K/T]cm3 s-1 (2)  The results obtained for methanol are in excellent agreement with results obtained by other workers, but the Arrhenius parameters for ethanol are markedly different to those obtained in the only other study of the temperature dependence of this reaction. The rate constant for reaction with (D3)methanolhas been determined at 293 K: (D3)Methanol ����� k(293) = 5.0�0.2×10-13 cm3 s-1 (3) The presence of an isotope effect confirms that the predominant process is abstraction of hydrogen from the carbon rather than the oxygen. The results obtained for the reaction with ethanol were analysed by using a 21 reaction scheme to determine the effect of [OH]O and secondary reactions on k(T). The simulations indicate that secondary reactions involving OH are relatively unimportant in determining the bimolecular rate coefficients found in this study.

scholarly journals Influence of cyclodextrin on the solubility of a classically prepared 2-vinylcyclopropane macromonomer in aqueous solution

2012 ◽  
Vol 8 ◽  
pp. 1528-1535 ◽  
Author(s):  
Helmut Ritter ◽  
Jia Cheng ◽  
Monir Tabatabai
Keyword(s):  
Aqueous Solution ◽  
Carboxylic Acid ◽  
Graft Copolymer ◽  
Ring Opening ◽  
Main Chain ◽  
Double Bonds ◽  
Radical Ring ◽  
Unsaturated Polymer ◽  
End Group ◽  
Clouding Point

A macromonomer 5 consisting of a polymerizable vinylcyclopropane end group and a poly(N-isopropylacrylamide) (poly(NiPAAm)) chain was obtained from amidation of 1-ethoxycarbonyl-2-vinylcyclopropane-1-carboxylic acid (4) with an amino-terminated poly(NiPAAm) 3 as an example. This macromonomer 5 showed an LCST effect after complexation of the vinyl end group with ß-cyclodextrin in water. Via radical ring-opening copolymerization of 5 and NiPAAm a graft copolymer 8 with a clouding point of 32 °C was synthesized. The branched unsaturated polymer was treated with ozone to cleave the double bonds of the main chain.

scholarly journals Development of an Environmentally Friendly Resist-Removal Process Using Wet Ozone

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Hideo Horibe ◽  
Yousuke Goto
Keyword(s):  
Plastic Deformation ◽  
Carboxylic Acid ◽  
Ion Implantation ◽  
Main Chain ◽  
Side Chain ◽  
Double Bonds ◽  
Removal Rates ◽  
Chemical Structures ◽  
Tof Sims ◽  
Ion Implanted

We investigated the removal of polymers with various chemical structures and the removal of ion-implanted resists using wet ozone. The removal rates of polymers that have carbon-carbon (C–C) double bonds in the main chain were high. The main chain of these polymers may be decomposed. The removal rates of polymers that have C–C double bonds in the side chain were low. The benzene ring in the side chain changes into carboxylic acid, so their ability to dissolve in water increased. The polymers without C–C double bonds were not removed. Removal of B and P ion-implanted resists became difficult with increasing acceleration energy of ions at implantation. The resist with plastic-deformation hardness that was twice as hard as that of nonimplanted resist should be removed similarly to nonimplanted resist. Using TOF-SIMS, we clarified that the molecule of cresol novolak resin was destroyed and carbonized by ion implantation.

The study of structural non-rigidity of molecules with double bonds in the main chain

1984 ◽  
Vol 26 (9) ◽  
pp. 2133-2147 ◽  
Author(s):  
A.L. Rabinovich ◽  
V.G. Dashevskii(dec.)
Keyword(s):  
Main Chain ◽  
Double Bonds

Modification of silicon-substituted polynorbornenes by epoxidation of main chain double bonds

2016 ◽  
Vol 58 (6) ◽  
pp. 695-702 ◽  
Author(s):  
A. A. Morontsev ◽  
M. L. Gringolts ◽  
M. P. Filatova ◽  
E. Sh. Finkelshtein
Keyword(s):  
Main Chain ◽  
Double Bonds
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