摘要:

The thermal decomposition of the bifunctional peroxide 2,2-bis(tertbuty1 peroxy)butane was investigated in a flow reactor at temperatures of 135 to 212°C and pressures of up to 2000 bar. The concentration of the peroxide in isododecane was varied between 1 and 22% by weight. The rate of decomposition measured was used to determine the energy of activation (EA= 151.1 ± 3 kJ/mol) and the activation volume (Δv” = 22.3 mL/mol). Up to a peroxide concentration of 5% by weight, the decomposition takes place according to a firat-order rate equation. Above this concentration, induced decomposition takes effect. Gas chromatographic analysis showed that the liquid decomposition products consisted mainly of acetone and tert-butyl alcohol apart from methyl ethyl ketone, propionic acid methyl ester, acetic acid ethyl ester, tert-butyl methyl ether, and oligomers of the solvent. The gaseous decomposition products consisted of methane and carbon dioxide as well as small quantities of ethane, propane, and ethylene. A theoretical explanation of the mechanism of decomposition is postulated which explains the spectrum of these components and its changes as a function of the peroxide concentration, the residence time, the temperature, and the pressure.

ISSN:0022-233X    

DOI:10.1080/00222338508063327

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The radical copolymerization of dialkyl citraconate (DRC, R˭CH3, C2H5, n-C3H7, i-C3H7, n-C4H9, i-C4H9, s-C4H9, C6H11, C6H5CH2) (M1) with styrene (ST, M2) was performed at 60°C, using azobisisobutyronitrile as the initiator in tetrahydrofuran in order to clarify the polymerization behavior of DRC and the substituent effects on copolymerization. The monomer reactivity ratios r1and r2and the Q1and e1values were determined from the results obtained. It was found that the relative reactivities 1/r2of DRC toward an attack by a polystyryl radical could be correlated not by the steric-substituent constant ESof the alkyl group in DRC, but by the polar-substituent constants σ* in Taft' equation: log (1/r2) = ρσ+δES. It was also observed that the e1values are associated with Taft' σ constant. It was found that the weight-average molecular weights of the copolymers are between 8.5 × 103and 1.4 × 104.

ISSN:0022-233X    

DOI:10.1080/00222338508063328

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Methyl methacrylate and other monomers were polymerized in systems involving cellulose completely or partially dissolved in complex solvents. Both the system [dimethylsulfoxide-sulfur dioxide] and the system [dimethylformamide-copper nitrate-cumene hydroperoxide] were found to be effective in initiating polymerization. In the presence of air, cellulose seemed to counteract the inhibiting effect of oxygen. All the reactions resulted in the formation of homopolymer only, and no graft co-polymers of cellulose were detected in the products.

ISSN:0022-233X    

DOI:10.1080/00222338508063329

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Saponification kinetics of acrylic terpolymer and polyacrylonitrile were studied. The influence of alkali concentration and the time of hydrolysis on the degree of saponification were determined by the residual nitrogen content. The order of reaction was graphically determined and the rate of saponification was found to be faster in the terpolymer than in the homopolymer. Chemical and infrared spectroscopy methods reveal that the reaction is initiated through cyclization of nitrile groups, followed by hydrolysis to amide and carboxylic groups of the ‒(C˭N)n‒ segments produced.

ISSN:0022-233X    

DOI:10.1080/00222338508063330

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The reactivity ratios of acrylonitrile copolymerization published from 1971to 1982 are tabulated.

ISSN:0022-233X    

DOI:10.1080/00222338508063331

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Methyl methacrylate was grafted onto poly(vinyl oxazoline ester) and poly(stearyl methacrylate) by a chain transfer suspension polymerization method to produce specialty polymeric products. These graft polymers should find application in powder coating, toner resin, and for encapsulating electronic components.

ISSN:0022-233X    

DOI:10.1080/00222338508063332

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Linear free energy relations are successfully extended to the principle of polylinearity when propagation is the predominant rate-determining step and others (e.g., initiation, termination) can be neglected. The cationic polymerization of vinyl ethers and p-substituted styrenes provides improved insight into the mechanism. On the other hand, the overall rate of the homopolymerization or the relative reactivity of the cross-propagation step in copolymerization can be controlled by means of multi-parameter equations. Some examples are given where multi-parameter correlation analysis with rather empirical parameters are shown useful for controlling industrial processes as well as for definite product formation.

ISSN:0022-233X    

DOI:10.1080/00222338508063333

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Graft copolymers of acrylamide and yellow dextrin were prepared using cerium(IV) as initiator. The yellow dextrin had a very broad molecular weight distribution but was fractionated utilizing dialysis and ultrafiltration membranes. Initiator efficiencies were determined using size exclusion chromatography and were found to be between 2.4 and 34%. Initiator efficiency increased with acrylamide concentration at constant cerium (IV) and yellow dextrin concentrations, and decreased with increasing cerium(IV) concentration at constant acrylamide and yellow dextrin concentrations. Plots of acrylamide conversion and intrinsic viscosity vs initial acrylamide concentration at constant yellow dextrin and ceric ion concentrations showed a maximum at about 2.0 M.

ISSN:0022-233X    

DOI:10.1080/00222338508063334

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The polymerization of ethylene oxide (EO) initiated by NaA1Bu4is shown to proceed upon initial complex formation between monomer and initiator. In polymerization in toluene a high order of the kinetic equation with respect to initiator was found, indicating that chain propagation proceeds on dimers and trimers of the active center. An induction time of polymerization in THF is observed. It is necessary to reach a specific concentration of the NaAIBu4.EO complexes which take part in the polymerization process. The wide molecular weight distribution, the high effectivity coefficient (initiation efficiency), and the polymerization rate increase with polymer yield are evidence of a polycentric polymerization mechanism.

ISSN:0022-233X    

DOI:10.1080/00222338508063335

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Copolymerization of 1,3-dioxolane (DOX) with trioxane in the solid state was studied by radiation. The effects of radiation dose, DOX concentration, postpolymerization temperature and duration on the copolymer yield, and DOX incorporation were investigated and compared with published data.

ISSN:0022-233X    

DOI:10.1080/00222338508063336

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor