摘要:

AbstractTrimethylammonium‐2‐hydroxypropyl (TMAHP) derivatives of spruce wood meal (SWM) and holocellulose of this specia were prepared by the reaction of wood meal with 3‐chlor‐2‐hydroxy‐propyltrimethylammoniumchloride (CHMAC) in alkaline medium. The TMAHP samples were fractionated and yields and exchange capacity (Q) of individual fractions were compared with beech and aspen fractions obtained under the same conditions. As it is evident from13C‐NMR spectroscopy and GPC analysis the water soluble fraction from TMAHP–SWM consists only of lignin–saccharide degradation products. The NaOH extracts of TMAHP–SWM and TMAHP–holocellulose as well as the water‐soluble fraction from TMAHP–holocellulose are polymeric materials. From TMAHP–SWM only 3.1% of alkali‐soluble material could be extracted, while from TMAHP–holocellulose 15.7% of water‐soluble and 7.9% of alkal

ISSN:0021-8995    

DOI:10.1002/app.1987.070330801

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

年代:1987

数据来源: WILEY

摘要:

AbstractAn emulsion polymerization of styrene in the presence of an amphoteric emulsifier of amino‐acid type,N‐lauroyl‐N,N‐dimethyllysine (DMLL), has been studied at pH 7.0. The polymerization rate increased exponentially with the concentration of DMLL. The concentration of latex particles was proportional to the DMLL concentration to the 0.6 power. The latex particle size decreased with increasing concentration of DMLL. The molecular weight of polystyrene latexes increased with an increase in DMLL concentration. Furthermore, the zeta potentials of latex particles were significantly dependent on the pH, and showed the existence of an isoelectric point at about

ISSN:0021-8995    

DOI:10.1002/app.1987.070330802

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

年代:1987

数据来源: WILEY

摘要:

AbstractTransport of liquid cyclohexane through well characterized, initially glassy, crosslinked polystyrene slabs was investigated. The samples were produced by bulk polymerization of styrene and divinyl benzene using benzoyl peroxide as an initiator at 90°C for 48 h; they had initial crosslinking ratios, X, between 0.005 and 0.025 mol DVB/mol styrene, initial thickness of 0.25 mm to 1.80 mm, and the aspect ratio was maintained above 10 to achieve one‐dimensional transport. The results of cyclohexane uptake as a function of time were used to elucidate the effects of degree of crosslinking and sample geometry on the mechanisms of penetrant transport. These results were interpreted in terms of relaxational and diffusional mechanis

ISSN:0021-8995    

DOI:10.1002/app.1987.070330803

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

年代:1987

数据来源: WILEY

摘要:

AbstractTensile mechanical properties of DOP‐plasticized poly(vinyl chloride) (PVC) and methyl methacrylate‐butyl acrylate copolymer (MMA‐BA) or ethylene vinyl acetate‐vinyl chloride copolymer (EVA‐VC) modified PVC have been studied. The irreversible deformation processes have been investigated using optical microscopy. Thermal analysis and x‐ray diffraction were used to investigate the structure of the PVC blends. The differences in behavior observed for the modified and plasticized PVC are discussed on the basis of their

ISSN:0021-8995    

DOI:10.1002/app.1987.070330804

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

年代:1987

数据来源: WILEY

摘要:

AbstractGrafting of the mixture of acrylamide and acrylic acid onto polyester and polypropylene fibers and mixture of acrylic acid and methacrylic acid onto polypropylene by the radiation method are reported. It is observed that when pure acrylamide was used for grafting, the grafting extent was small, whereas when the mixture was used, the amount of acrylamide content in the copolymer was found to be more than the feed ratios. The results are explained on the basis of chain transfer mechanism. With methacrylic acid and acrylic acid mixtures, the rate of grafting decreased with the increase in the concentration of acrylic acid in the feed ratio, and this has been explained on the basis of the formation of either a 3‐dimensional network structure or a highly branched structure involving backbone polymer molecules with acrylic acid, which prevents the diffusion of the monomer from the solution phase to the swollen phas

ISSN:0021-8995    

DOI:10.1002/app.1987.070330805

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe photostability of polyamidoimide (PAI) and polyimide (PI) films has been studied. UV irradiation caused a great change in the composition and structure of the film surface. With irradiation in atmospheres such as air, oxygen, and an oxygen—nitrogen mixture, the Cls spectrum had a distinct structure at high binding energy, and the O/C and N/C ratios were considerably increased. On the other hand, in nitrogen and under vacuum, the O/C and N/C ratios remained almost unchanged during an earlier stage of irradiation, but in the latter stage for the nitrogen atmosphere these ratios decreased to a broad minimum and then increased with an increase of irradiation time. UV irradiation also produced free radicals in the polymer films; PAI gave a much stronger ESR signal intensity than PI. The signal intensity vs. irradiation time curve was strongly influenced by irradiation atmospheres. In atmospheres containing oxygen the curve exhibited a broad maximum during an initial stage of irradiation, while under vacuum and in nitrogen the signal intensity increased greatly in the latter stage. The formation of free radicals during an earlier stage of irradiation in atmospheres containing oxygen was promoted by the oxygen incorporated at the film surface, while the radical production under vacuum was considered to be due to rupturing of bonds in the bulk material. The decay of free radicals in the dark after irradiation occurred at a faster speed in oxygen atmospheres than under vacuu

ISSN:0021-8995    

DOI:10.1002/app.1987.070330806

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

年代:1987

数据来源: WILEY

摘要:

AbstractTwo methods have been used to introduce hydroxyl groups into natural rubber. In the first method, epoxidized natural rubber was reduced with lithium aluminium hydride or aluminium hydride with the production of a tertiary alcohol. The13C NMR spectrum of this product was assigned in terms of shift factors from model compounds and quantitative analysis of the spectra confirmed that the hydroxylation process of partially epoxidized rubber was a random process. At higher levels of epoxidation, evidence was obtained for the formation of larger rings from adjacent epoxy groups. The second method involved hydroboration of natural rubber followed by oxidation, which was expected to produce secondary alcohol groups, but gave a mixture of secondary and tertiary alcohol groups as shown by the13C NMR spectrum. A reaction scheme was proposed to explain this result.

ISSN:0021-8995    

DOI:10.1002/app.1987.070330807

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

年代:1987

数据来源: WILEY

摘要:

AbstractRadiation‐initiated grafting of methacrylic acid, acrylonitrile, and vinyl acetate on polypropylene fibers and the moisture content and dyeing characteristics of the grafted fibers have been reported. The extent of grafting with methacrylic acid is quite large when compared to acrylonitrile and vinyl acetate. The grafted fibers show an increase in moisture content with increase in the amount of graft. In general, the dyeability with disperse dyes increases due to grafting. In the case of cationic dyes, the polypropylene fibers grafted with methacrylic acid and acrylonitrile alone could be dye

ISSN:0021-8995    

DOI:10.1002/app.1987.070330808

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

年代:1987

数据来源: WILEY

摘要:

AbstractElectrokinetic properties of methacrylic acid‐ and acrylonitrile‐grafted polypropylene fibers measured in the presence of cationic dyes are reported. The zeta potential of polypropylene fibers decreases, and the surface charge density along with surface conductivity increases as the concentration of the dyes in the streaming solution increases. The zeta potential at pH 7 decreases as the amount of graft increases in case of both acrylonitrile‐ and methacrylic acid grafted fibers. Both surface charge density and surface conductivity increase with the increase in dye concentration for both acrylonitrile‐ and methacrylic acid‐grafted fibers. The results are explained on the basis of the cationic dye adsorption on the grafted fiber in the case of methacrylic acid graft. In the case of acrylonitrile‐grafted fibers, this could be due to the strong attraction of cationic dye to the nitrile group of the gra

ISSN:0021-8995    

DOI:10.1002/app.1987.070330809

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

年代:1987

数据来源: WILEY

摘要:

AbstractElectrical conductivity of polypropylene fibers grafted with methacrylic acid, vinyl acetate, and acrylonitrile for the samples conditioned at various relative humidities is reported. Electrical conductivity increases with the increase in graft in all three grafted polymers. The increase in conductivity of polypropylene fibers grafted with methacrylic acid is two orders of magnitude higher than control, while the increase in other cases in small. The results are explained on the basis of chemical structure of the grafted fibers. Increase in electrical conductivity with respect to methacrylic acid graft could be due to charge migration and electronic conductivity. In the case of the other two monomer‐grafted PPs, increase could be predominantly due to electronic conductio

ISSN:0021-8995    

DOI:10.1002/app.1987.070330810

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

年代:1987

数据来源: WILEY