摘要:

AbstractTwo types of carbon black namely fast extrusion furnace black (FEF) and high abrasion furnace black (HAF) were incorporated with a concentration of 50 phr into styrene butadiene rubber (SBR) and natural rubber (NR). The effect of the time of aging and temperature on the electrical conductivity was studied. It was found that a thermal aging at 95°C leads to the appearance of minimum in conductivity (σ) in both FEF/NR and HAF/NR. This was explained by a competition between two factors: degradation and increase of crosslinking density in the rubber matrix. In case of FEF/SBR and HAF/SBR it seems that these factors have comparable effects on the conductivity after 10 days of aging. From the current‐voltage (I‐V) characteristics the carrier concentration, trap density, and the drift mobility were calculated. The minimum found in the temperature dependence of σ for FEF/NR is discussed and found to be controlled by the relative dimension of carbon and rubber aggr

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051290101

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractA water soluble muco‐polysaccharide, “dextran”, was subjected to selective degradation and graft copolymerized with acrylamide and methylmethacrylate. Using ceric ions as initiator a low molecular weight model dextran and dextran‐g‐poly(acrylamide) as well as dextran‐g‐poly(methylmethacrylate) copolymers were prepared. The selective chain degradation and the graft copolymerizations were carried out at varying concentrations of Ce(IV) and monomer and varying temperatures. The course of degradative chain cleavage has been followed by viscometry. The low molecular weight model dextran and the copolymers were purified by usual methods. Their physical and chemical properties were tested and compared with the base. The energy of activation for the chain degradation and other related thermodynamic parameters have b

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051290102

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractPolymeric peroxycarbamate initiators containing polyazoester or polyethylene adipate blocks were synthesized. They can be used to prepare multiblock copolymers by radical polymerization in a procedure involving several steps. Bulk and solution polymerizations are suitable techniques in these steps.The polymerization of styrene with these initiators was investigated over a wide range of conversion. Longer polymerization times led to an expected decrease in peroxygen contents of the active polystyrenes.Styrene/methyl methacrylate/n‐butyl methacrylate, polyethylene adipate/styrene/methyl methacrylate, polyethylene adipate/styrene/methyl methacrylate/n‐butyl methacrylate and polyethylene adipate/styrene/methyl methacrylate/acrylonitrile multiblock copolymers were obtained in this

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051290103

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractAll grades of carbon black contain large amounts of unpaired electrons and organic functional groups. Polymerization reaction is possibly initiated by the unpaired electrons on the surface; the functional groups have promotional effect on the initiation process. All the properties like texture, geometry, surface area, pH of the aqueous slurry, ash content, and elemental composition have effects on the polymerization reaction. These pertinent physicochemical and surface properties of unmodified and modified N 220 carbon black have been studied in relation to N‐vinylcarbazole polymerizatio

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051290104

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe suitability of difunctional organic peroxides for the synthesis of low density polyethylene (LDPE) was examined with a view to improve the results. Polymerization tests were carried out in a stirrer autoclave pilot plant using three different difunctional compounds with different levels of thermal stability at a pressure of 1700 bar and temperatures of between 180 and 290°C. The conversion and the specific peroxide consumption were measured and the average molar masses of the polymers obtained were determined. The solubility of the peroxides in isododecane was also examined

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051290105

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractSolution and bulk polymerizations of hexachloro cyclotriphosphazene (NPCl2)3were carried out using molybdenum silicate and tungsten silicate as catalysts. The polymer did not form by the solution polymerization, but was obtained by the bulk polymerization. When tungsten silicate was used, a linear polymer was predominantly formed.

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051290106

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractFilms of a plasticized random terpolymer were prepared by evaporation of solutions in several solvents. The glass transition temperatures of the films were determined and were found to follow the Fox's equation. Their tensile modulus, measured just below the glass transition temperature, was found to depend on the residual solvent content of the films.

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051290107

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractProton spin‐lattice (T1) and spin‐spin (T2) relaxation times of isotactic polypropylene films with different thermal histories, treated with tetrachloroethylene, were measured with pulsed NMR. For the melt‐quenched sample T11(the longer T1) increases and T2a(the longest T2) decreases with increasing treatment temperature. The mass fraction of mobile region (Fa) decreases and the mass fraction of rigid region (Fc) increases with increasing treatment temperature. T11increases almost linearly with increasing Fc, indicating that the removal of the mobile amorphous region is mainly responsible for the change in T11.For the annealed sample T11also increases with increasing treatment temperature, although a slight decrease in T11for the low treatment temperature is observed. There is a large decrease in T2awhen the treatment temperature is raised, suggesting that a comparatively selective extraction occurs for the annealed s

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051290108

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe properties of solution‐mixed blends of isotactic polypropylene (iPP) and an amorphous ethylene‐propylene copolymer (EPM), containing 40 wt.‐% of ethylene, were studied throughout the composition range. The techniques used were differential scanning calorimetry (DSC), dynamic mechanical spectroscopy, and optical microscopy. Morphological examination revealed a heterogeneous structure. The dynamic mechanical technique at isochronous conditions (110 Hz) between ‐120 and 160°C confirmed the heterophase nature of the blends and revealed limited phase mixing of the amorphous components of the two constituents. DSC measurements of specimens quenched at 0°C, indicated that EPM rubber promotes crystallization of the iPP phase.Appropriate mechanics models tested in the complete composition range led to the conclusion that the system is incompatible, with rubber spherical inclusion strongly adhering to the iPP matrix, up to an EPM volume fraction Φ (EPM) ≃ 0.70. At higher EPM compositions, matrix reversal occurs — a fact corroborated by the available mechanical data

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051290109

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractCopoly(etherurethane‐urea)s (PEUU) from different polyethers with hydroxyl endgroups, with 4,4′‐diisocyanato‐dicyclohexylmethane and 4,4′‐diamino‐diphenylmethane (as a chain extender) were heated linearly within the ion source of a mass spectrometer. The analysis of the evolved gases allows the identification and detailed characterization of the investigated polymers. The building units of PEUU — polyethers, diisocyanates, and the diamine — can be identified by key fragments. These are formed during pyrolysis and can be identified with field ionization or low‐voltage electron impact ionization.Furthermore, the polyethers with hydroxyl endgroups as well as the PEUU can easily be distinguished by their volatilization rate curves. Fragments resulting from cleavages of the different bond types present, e.g., urea, urethane, ether in this order, are generated during the linear increase of temperature; they are pinpointed by repetitive scanning

ISSN:0003-3146    

DOI:10.1002/apmc.1985.051290110

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY