摘要:

The effects of sensitizer, alcohol, and reaction temperature on the photosensitized polymerization of methyl methacrylate in cyclohexane-alcohol mixtures were investigated. A maximum conversion was indicated at a certain concentration of alcohol in the mixture for the systems sensitized with quinones such as anthraquinone, 2-tert-butylanthraquinone, and α-naphthoquinone, while it was not observed for the benzophenone-sensitized system. The concentration of alcohol corresponding to the maximum conversion increased in the order methanol < ethanol < n-propanol < n-butanol, and shifted to the lower side by raising the reaction temperature from 20 to 40°C. Based on the absorption and ESR spectra of irradiated solution of quinones, reasons for maximum conversion at an optimum concentration of alcohol are discussed.

ISSN:0022-233X    

DOI:10.1080/00222338208082062

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Photopolymerization of methyl methacrylate in visible light was studied at 40°C using a pyridine-sulfur dioxide charge transfer complex as the initiator in the presence of carbon tetrachloride. In this study the [Py-SO2] used was high (0.5–3.2 mol/L), i.e., 6–40% (V/V), and the [CCL4] ranged between 0 and 1.4 mol/L, i.e., 0–10% (V/V). At a fixed [Py-SO2], Rpfollowed an increasing trend with increasing [CCL4] until the latter was about 2–3% of the total volume. The polymerization rates may be expressed as where Rpand Rp0are rates of photopolymerization in the presence and in the absence of CCL4, respectively. The overall rate, Rp, is proportional to [CCL4]0.5for [CCL4] & 0.2 mol/L.

ISSN:0022-233X    

DOI:10.1080/00222338208082063

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Our previous NMR investigations of chemically cross-linked polypropylene were mainly focused on testing the relation between spin-spin and spin-lattice relaxation times as a function of cross-linking compound concentration. In our previous investigations, however, we did not consider the state of mobility of any part of the polypropylene chain, and therefore in this work we consider this problem.

ISSN:0022-233X    

DOI:10.1080/00222338208082064

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Polyazomethine chelate polymers of 3d transition metal ions have been prepared and characterized in terms of elemental analysis, magnetic moment, electronic spectra, infrared spectra, and thermal and electrical properties. All the polymers exhibit 1:1 stoichiometry and are insoluble in common organic solvents.

ISSN:0022-233X    

DOI:10.1080/00222338208082065

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The effect of swelling in kerosene on the electrical conductance of 60, 80, and 100 part per hundred parts of rubber by weight of Fast Extrusion Furnace (FEF) carbon black-loaded styrene-butadiene rubber (SBR, 1502) was studied. It was found that there is a characteristic time of swelling after which a sudden decrease in conductivity appears. An ideal and simple model is suggested to calculate the carbon-carbon interspacing distance, D, in the carbon/rubber matrix. The dependence of D on the swelling time is also discussed.

ISSN:0022-233X    

DOI:10.1080/00222338208082066

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The polymerization of acrylonitrile initiated by potassium bromate coupled with thioacetamide was investigated in aqueous solution under nitrogen atmosphere. The effect of monomer, initiator, activator, and acid concentration on the rate of polymerization as well as on maximum conversion was evaluated. The rate of polymerization was found to increase up to 1.25 × 10−3Mof initiator concentration and thereafter it decreased. The rate of polymerization also increased with the monomer and activator concentration up to 1.5078 and 4.0 × 10−3M, respectively, after which the rate fell. The effect of acid concentration, temperature, and solvents on rate of polymerization has been studied and a suitable kinetic scheme has been pictured.

ISSN:0022-233X    

DOI:10.1080/00222338208082067

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The osmotic coefficient g* is calculated for sodium carboxymethylcellulose (NaCMC) samples of different degrees of substitution. The dependence of g* onDS, concentration of NaCMC, and added NaCl has been investigated for all samples. The true osmotic coefficient has also been calculated for all the samples by applying Donnan's equilibrium concept. is found to be independent of the amount of extraneous salt accounting for Donnan's membrane equilibrium. The dependence of on the charge density of polyions can be explained quantitatively by Oosawa's and Katchalsky's theories.

ISSN:0022-233X    

DOI:10.1080/00222338208082068

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Some kinetic features of the grafting of methyl methacrylate onto polyethylene terephthalate initiated by the potassium bromate-thiourea redox system have been investigated in aqueous solution. The effects of potassium bromate, thiourea, monomer, acid, and temperature upon percentage grafting have been determined. The activation energy of the reaction has been computed from an Arrhenius plot. Grafting experiments have been carried out in the presence of such conventional chain-transfer agents as CC14and CHC13. The effect of CuSO4upon grafting is also studied. The reaction mechanism involved during grafting is pictured.

ISSN:0022-233X    

DOI:10.1080/00222338208082069

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

In an attempt to initiate grafting, methyl methacrylate (MMA) has been grafted separately to Chokla wool and Mulberry silk in aqueous medium by using the potassium peroxydiphosphate-2-amino ethane thiol (PP-AET) system as redox initiator. Percent grafting is determined as a function of concentration of MMA, concentration of PP, concentration of AET, concentration of sulfuric acid, time, and temperature. Sulfuric acid is found to catalyze the reaction to a certain extent. The rate of grafting (Rp) and the induction period (Ip) of MMA are determined as a function of the total initial monomer concentration. The moisture regain properties and infrared spectra are studied. The reaction scheme is pictured.

ISSN:0022-233X    

DOI:10.1080/00222338208082070

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Polysilicone tubing retained 79 to 93% of its original flexibility after radiation grafting with 2-chloroethylacrylate (CEA), quaternization with pyridine, and heparinization. The amount of CEA grafted was linear with time following an induction period. Sample flexibility was studied as a function of CEA addon, pyridine add-on, and heparin add-on. Grafted CEA was found to increase the flexibility of the tubing, thus tending to offset the stiffening effects of the quaternization and heparinization reactions. Tensile moduli and compression load measurements were compared for heparinized and untreated tubing.

ISSN:0022-233X    

DOI:10.1080/00222338208082071

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor