摘要:

AbstractThe solubility of ethylene was measured in water, water–tert‐butyl alcohol, water‐emulsifier, water‐tert‐butyl alcohol‐emulsifier, and water–tert‐butyl alcohol–emulsifier–polyethylene. The polymerization of ethylene in an emulsion system differs from that of other vinyl monomers in several ways: the rate of polymer formation is inversely proportional to the emulsifier concentration and to the number of particles, the molecular weight of the polymer increases as the particle size increases, the polymer contains bound emulsifier whose concentration depends inversely on the particle diameter. These peculiarities are attributed to a transfer reaction between polymer radicals and emulsifier adsorbed on the surface of the polymer particle. In the presence of a fatty‐acid soap, the transfer probably occurs primarily at the carbon α

ISSN:0021-8995    

DOI:10.1002/app.1967.070110101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractThe adduct of Kaolin and 2,2′‐azobisisobutyramidine hydrochloride has been used to initiate the polymerization of methyl methacrylate, styrene, styrene‐butadiene, vinyl acetate, chloroprene, acrylamide, and acrylonitrile. Both extractable and nonextractable polymers are obtained. The adduct of bentonite and 2,2′‐azobisisobutyramidine hydrochloride will initiate the polymerization of methyl methacrylate, acrylamide, vinyl acetate, 4‐vinylpridine, and styrene. Both extractable and nonextractable polymers are formed. When the bentonite or the hectorite adducts are more than 99% decomposed prior to the addition of methyl methacrylate, essentially no extractable polymer is formed, but an increased quantity of nonextractable polymer is produced. This is probably due to an increased accessibility of the monomer to the clay's interior surface and a decrease in the rate of chain termination. As is the case of the kaolin adduct, the clay surface of bentonite appears to accelerate the chain growth c

ISSN:0021-8995    

DOI:10.1002/app.1967.070110102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractA quantitative characterization of natural rubber, both as the raw polymer, and unaccelerated vulcanized samples containing different proportions of sulfur and ranging from soft to hard rubber, is reported. A value of 86% of the chains of natural rubber could be accounted for against 37% as reported by Harries assuming that levulinic acid is the sole degradation product. About 5% of the chain is present as a 3,4 structure which gives rise to formic acid in the degraded product. A small amount of sulfuric acid is present in the degradation product from the vulcanized samples, which decreases with the increases in the percentage of sulfur in the stock as well as the cure time. A chromatographic technique for the separation of levulinic, acetic, and formic acid in the presence of sulfuric acid is reported. It is observed that the total amount of carbon main chain escaping sulfuration decreases and the amount of insoluble fraction increases with increasing proportion of sulfur in the stock.

ISSN:0021-8995    

DOI:10.1002/app.1967.070110103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractCopolymerization of unsaturated polyester with styrene in water‐in‐oil (W/O) type emulsion was carried out with the use of various basic compounds as emulsifiers. It was found that a stable, gellike W/O type emulsion of unsaturated polyester resin is formed only when pKa's of the bases are above 6 and their concentrations are higher than some critical value. In these conditions, water can be dispersed in emulsion up to 900% to the resin. By polymerization, the stable W/O type emulsion is transformed to a white solid copolymer which is dry to the touch and which contains 90–95% of initially added water. It was confirmed that the basic compounds react with the carboxylic group of the polyester to form at the water‐resin interface polyester salts, which act as true emulsifying agents. The stabilization mechanism of the emulsion at various concentrations of the polyester salt was investigated, mainly by microscopic observations, and an interpretation of the critical value of emulsifier concentration is p

ISSN:0021-8995    

DOI:10.1002/app.1967.070110104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractComplexes of aluminum alkyls with Lewis bases catalyze the polymerization of vinyl chloride. Triethylaluminum is most effective, but other compounds of type R3Al, R2AlCl, R2AlH, and LiAIR4are operable. Dialkylmagnesiums are active, but Grignard reagents, as well as a number of other metal alkyls are inactive. Among Lewis bases, tetrahydrofuran (THF) and tetrahydropyran give the best yields of poly(vinyl chloride). Oxygen bases, such as ethers and esters, are more effective than nitrogen bases, e.g., tertiary amines. Cyclic compounds are better than acyclic ones. The polymerization occurs in a variety of hydrocarbon, chlorinated hydrocarbon, or ether solvents, but especially well in CCl4. Radical polymerization is probably initiated through the reaction R3Al:Base + CCl4→ R2AlCl: Base + R + Cl3C., to form trichloromethyl radica

ISSN:0021-8995    

DOI:10.1002/app.1967.070110105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractThe process of resole‐type phenol–formaldehyde resins was studied by differential thermal analysis and infrared spectroscopy. It was shown that in neutral media the first reactions that occur are those between free phenol present in the resin and monosubstituted methylol phenol with free reactive positions on the benzene ring. The formation of methylene linkages is followed immediately by the condensation of methylol groups to give dibenzyl ether linkages. These are subsequently destroyed at about 210°C. It is believed that the entire curing process is governed by a free‐radical mechanism. It is also shown that oxidation of the resin occurs slowly at room temperature and hu

ISSN:0021-8995    

DOI:10.1002/app.1967.070110106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractThe kinetics of formation of dibenzyl ether linkages during cure of resole‐type phenol‐formaldehyde resins was studied by the use of differential thermal analysis and infrared spectroscopy. The activation energy was 21.6 kcal./mole by the Borchard and Daniels method gives and 18.6 kcal./mole by the Kissinger method. For the same process, infrared, which shows a rather good agreement between the two different methods. The heat of reaction, determined from the area under the DTA curve for the corresponding reaction, was found to be 20.2 cal

ISSN:0021-8995    

DOI:10.1002/app.1967.070110107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractIn order to assess the dependence of strength properties of glassy polymers upon the extent of branching, copolymers of poly(styrene–acrylonitrile) were prepared. By using principally three methods: (a) hydroperoxide intermediates, (b) hydroxyl radical initiation, and (c) incorporation of transfer monomers, branched polymers with high levels of branching with comb and dendritic type structures were generated. The tensile strength was found to be strongly correlatable with melt flow, and, in general, the branched copolymers were found to have the same tensile strength as linear polymers of the same melt inde

ISSN:0021-8995    

DOI:10.1002/app.1967.070110108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractGraft copolymerization of vinyl monomers, mainly methyl methacrylate, in reduced, successively alkylated, or KCN‐Treated wool fibers was performed in the redox LiBr–persulfate system without homopolymer. The reduction gives a striking effect in promoting the graft copolymerization. Methylation or ethylene recrosslinking of the reduced wool, especially the former, decreases the graft‐on remarkably. By the KCN treatment in which the conversion of disulfide to lanthionine bonds occurs, the grafting is decreased in the bromide–persulfate system but promoted in the system with persulfate alone. Methylation or KCN treatment of wool as well as reduction brings about a great increase in the absorption of persulfate. The grafting of the lanthionine‐containing wool in the redox system accompanied by the liberation of bromine might be retarded by the pronounced bromination of monomers over the inhibiting of homopolymerization, because the lanthionine bonds are more stable to bromine than the disulfide bonds. In general, disulfide bonds and the other easily oxidized components of wool may perhaps play an important role in regulating the bromination of monomers and in the graft copolymerization without homopolymer. The molecular weight of graft polymer is decreased distinctly with increasing extent of reduction of wool. From these results, the thiol groups on wool are considered to give predominantly graft centers by the radicalotropy from SO4 −·, O

ISSN:0021-8995    

DOI:10.1002/app.1967.070110109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractAn analysis of the Maxwell orthogonal rheometer for polymer melts is made by using the constitutive equation of White and Metzner. The results indicate that the shear deformation involved is oscillatory and that the storage and loss moduli of the melt may be derived from the measured stress response.

ISSN:0021-8995    

DOI:10.1002/app.1967.070110110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY