摘要:

AbstractAtactic polypropylene was functionalized by reaction with dicumyl peroxide (8 wt.−%) and allyl compounds (8 wt.−%) such as eugenol methylether, allylphenylether, allylurea, N‐allylthiourea, diethyl allylmalonate, N‐allylaniline at 170°C. Using tert‐butyl azidoformate carbamate groups (1.8 wt.−%) were attached to atactic polypropylene. The mechanism of both types of reactions

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051500101

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractA procedure to obtain information concerning the low molecular weight compounds of dashboard foils is described. Solvent extracts of the foils were fractionated by preparative reversed or normal phase HPLC, respectively. The fractions were characterized by their infrared spectra. The benefits and the shortcomings of the two methods are discussed.

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051500102

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe electrical conduction was investigated in styrene butadiene rubber (SBR‐1502) loaded with different concentrations of fast extrusion furnace (FEF) black (70, 80, 90, and 100 phr). On the bases of Holm's model, a qualitative description for the electrical conduction through these composites was sought. The pressure coefficient K was calculated and found to be strongly dependent on the carbon black concentration

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051500103

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe dependence of electrical characteristics of copolymer complexes on ambient humidity was studied for complexes of quaternized 4‐vinylpyridine‐styrene copolymer/perchlorate complexes. When the 4‐vinylpyridine content in the copolymer increased, a linear decrease in resistivity was found. From this behaviour, it is concluded that the resistivity can be freely set by variation of the 4‐vinylpyridine content in the design of a sensor material. Furthermore, the resistivity was the smallest in the HClO4complex and successively became large in the order of the KClO4complex and the LiClO4complex. From the electrochemical aspect, it was cleared that the degree of dissociation of the counterion exerted influence upon the resistivity of these co

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051500104

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThermal behaviour of twelve different starches and their graft copolymers with polyacrylonitrile (PAN) from granular and gelatinized state, has been examined by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). All the starches exhibit two endotherms around 65 and 260°C and an exotherm around 335°C. The graft copolymer from granular starch shows a weak endotherm around 65°C and an exotherm around 300°C, while gelatinized starch exhibits the characteristic exotherm of PAN at about 250°C along with the exotherm of graft product at 300°C. Scanning electron microscopic studies were carried out to explain the endotherms of starch at 65°C and 265°C. The former one may be due to heat of dehydration while the latter one is attributed to the fusion of crystallites in the starch. Legumine starches seem to have a specific property of retaining moisture even if they are grafted in gelatinize

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051500105

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe graft copolymerization of methyl methacrylate (MMA) onto chemically modified tussa silk fibers in aqueous media using potassium peroxodisulfate‐thiourea redox initiator system was studied at 60°C. The effects of time of reaction, concentrations of oxidant, thiourea (TU), monomer (M), amount of silk fibers on graft yield have been studied. The effects of reaction medium, acid concentration, and some inorganic salts and organic solvents on grafting have also been investigated. A significant increase in percent of grafting was observed with increasing monomer concentration to 65.86 · 10−2mol · 1−1; a further increase of monomer concentration is associated with the decrease of graft yield. The graft yield increases with an increase of thiourea concentration up to 10 · 10−1mol · 1−1, beyond which it decreases very significantly. A measurable increase of the graft yield was also observed with an increase of the oxidant concentration up to 0.08 mol · 1−1beyond which the graft yield decreased. The graft yield was medium dependent. The reaction mechanism of the grafting process has been proposed and a rate expression has been derived on the basis of experimental findings. IR spectra of the grafted fiber and original fiber have been taken and their characteristic bands have been identified. The thermal behaviour of the original and grafted silk fibers has been studied by TGA and DTG analysis. Grafting has improved thermal stability as well as the light fastness of silk dyed

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051500106

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractPoly‐(bisphenol A carbonate) (PC) samples were exposed to different doses of γ‐rays from a60Co source (from 0.05 to 0.3 M rad) at room temperature. Conductivity and dielectric constant as well as optical measurements were carried out. It was noticed that almost no work has been reported on the electrical conductivity of polycarbonate at high temperatures. γ‐irradiation of polycarbonate is believed to create free radicals which increases the state of disorder and perturb the orientation of dipoles inside the polymer. At about 95°C, the electrical conductivities of irradiated samples were found to increase by nearly one order of magnitude with respect to the unirradiated one. The dielectric constant, ϵ, of fresh polycarbonate was nearly temperature independent over a range of ∼ 70°C, then it increased with temperature, but for γ‐irradiated samples (from 0.05 to 0.3 M rad) the dielectric constant increased continuously with temperature and also with respect to the fresh sample what confirms the effect of γ‐irradiation in perturbing the orientation of the dipoles in the polymer. It was found that the UV absorption spectrum has a broad band at 0.280 μm and the absorption intensity was strongly dependent on the do

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051500107

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe degradation of commercial LDPE was studied under dynamic conditions which simulate the processing. Dynamic oxidation above 140°C is similar to static oxidation under low oxygen pressure both having strong diffusion control. Fragmentation and crosslinking (mainly CC bonds) compete in the process. The hydroperoxides predominate at the beginning of the mixing. Their quantity rapidly decreases while that of oxo groups increases and becomes predominant.Below 140°C, the conditions are resembling to static oxidation performed under higher oxygen pressure but the process is still somewhat diffusion controlled. The change in the molecular mass is not considerable in the process. The hydroperoxides predominate among the functional groups formed. Their ratio is constant during mixing. The effect of mechanical stress is not considerable.An increase in the mixing speed resulted in an increase in the rate of the processes studied above.The higher the total amount of oxygen incorporated in the PE, the smaller is the remaining oxidative stabil

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051500108

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractNitric oxide initiated polymerization of acrylonitrile in dimethylsulfoxide was carried out. The dependence of monomer and initiator concentrations and temperature on polymer yield and initial rate of polymerization (Rin) was studied. The over‐all activation energy of polymerization was found to be about 19.96 kcal · mol−1(83.43 kJ · mol−1). The polymerization of acrylonitrile appears to occur via free radical mechanism. A kinetic scheme and rate expression have been p

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051500109

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractElectron impact mass spectrometry and mass ion kinetic energy spectrometry were used to analyze: (i) the structure of uncrosslinked, predominantly aliphatic chains obtained by pyridine extraction of bituminous coals; and (ii) the identity of compounds found in depolymerized coal samples produced by the technique of Hooker et al. (1986).

ISSN:0003-3146    

DOI:10.1002/apmc.1987.051500110

出版商:Hüthig&Wepf Verlag    

年代:1987

数据来源: WILEY