摘要:

AbstractThe soluble part of glow discharge polysilazane prepared from hexamethylcyclotrisilazane was studied. The composition of the soluble fraction was examined by gas chromatography and mass spectrometry. It was found that the fraction contained five main components, and two of them, identified by mass spectrometry, were octamethylcyclotetrasilazane and bicyclic silazane dimer. A reaction mechanism leading to dimer formation from hexamethylcyclotrisilazane in glow discharge was proposed.

ISSN:0021-8995    

DOI:10.1002/app.1977.070210801

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe effect of multiple steady solutions in isothermal perfectly mixed flow reactors is illustrated for polymerizations which have autocatalytic rates of initiation and no termination reactions. For feed conditions where more than one steady condition can exist, longer holding times may not necessarily yield higher molecular weight polymer or higher monomer conversions.

ISSN:0021-8995    

DOI:10.1002/app.1977.070210802

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

年代:1977

数据来源: WILEY

摘要:

AbstractMethods for obtaining kinetic data on bulk polymerizing systems are reviewed, and adiabatic temperature rise is found to be the most useful for fast systems. An adiabatic method is described and used to study the polymerization of poly(ε‐caprolactone triol) with chain‐extended 1,6‐hexane diisocyanate catalyzed with dibutyltin dil

ISSN:0021-8995    

DOI:10.1002/app.1977.070210803

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe stabilization mechanism by synergetic metal soaps containing complementary colors was previously reported. With increased heating times, the color of heated poly(vinyl chloride) (PVC) films containing Cd/Ba and Zn/Ca synergetic soaps markedly deviated from the polyene color. These color deviations usually decreased the thermal stability of PVC. Discoloration from polyene color to blue appeared especially on PVC films containing Zn/Ca synergetic soap and was concomitant with a marked decrease in thermal stability. The stabilization of PVC containing synergetic metal soaps can be improved by masking or removing the excessive color. In this work, the addition of various masking agents, such as ethylenediaminetetraacetic acid,o‐phenanthroline, triethanolamine, urea, N,N′ ‐dimethylolurea, melamine, stearylamide, and lactams, to PVC containing synergetic metal soaps was investigated. It was shown that these masking agents do markedly slow down the discoloration o

ISSN:0021-8995    

DOI:10.1002/app.1977.070210804

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

年代:1977

数据来源: WILEY

摘要:

AbstractData on reverse osmosis separations have been obtained for 12 alkali metal halide solutes and 24 organic solutes (including eight alcohols, four aldehydes, seven ketones, and five ethers) with cellulose acetate propionate (CAP) membranes using single‐solute dilute aqueous feed solutions at 250 psig. From the analysis of these data, the parameters and correlations needed to calculate the values of solute transport parameterDAM/Kδ for the above classes of inorganic and organic solutes for a CAP membrane of any surface porosity from data onDAM/Kδ for NaCl only have been generated. These parameters and correlations enable one to predict reverse osmosis separations of different solutes included in the classes of compounds studied in this work, from a single set of experimental data on membrane specifications given in terms of pure water permeability constant andDAM/Kδ for NaCl. The reverse osmosis characteristics of CAP material lie intermediate between those of cellulose acetate and aromatic polyamide materials reported in the litera

ISSN:0021-8995    

DOI:10.1002/app.1977.070210805

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

年代:1977

数据来源: WILEY

摘要:

AbstractTheGHCIvalues of γ‐irradiated PVC mixtures were studied after addition of various amounts of three epoxy stabilizers: diglycidyl ether of 2,2‐bis(4‐hydroxy‐3‐methylphenyl)propane (I); diglycidyl ether of 1,1‐bis(4‐hydroxyphenyl)cyclohexane (II), and butyl‐cis‐9,10‐epoxystearate (III). The results indicated that two processes are essential for the stabilization: HCI capture by the epoxy groups, and an external protective effect, due to the remaining part of the stabilizer molecule. The role of the benzene rings in stabilizers I and II, as compared with the protective effect due to the long chains of stabilizer III, is not as dominant

ISSN:0021-8995    

DOI:10.1002/app.1977.070210806

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

年代:1977

数据来源: WILEY

摘要:

AbstractUncured styrene–butadiene gum, a known cured composition, and four SBR beltings used in underground coal mining were subjected to thermal oxidative degradation in static and dynamic systems. The room temperature volatiles produced under the static conditions at 370°C were identified and quantitated. Monomers and their interaction products were liberated by the raw gum; the cured composition formed together with the above products materials traceable to the curing ingredients. The four beltings gave a large spectrum of products; an attempt was made to correlate these with possible components used in belts manufacture. In the dynamic system, the occurrence of glow, the rate of smoke generation, and char yields were determined at 400°C and 500°C. None of the materials glowed at 400°C. At 500°C, the raw gum volatilized completely, and the cured rubber and two beltings glowed. One of the beltings, which failed to glow, liberated the smallest quantity of toxic pr

ISSN:0021-8995    

DOI:10.1002/app.1977.070210807

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

年代:1977

数据来源: WILEY

摘要:

AbstractA new process of decrystallization of cellulosic materials8is described. The process involves the preparation of alkali‐cellulose and an interaction between alkali‐cellulose and acetic anhydride. The decrystallized products thus obtained are partially acetylated and are designated as SPA (S for swollen, PA for partially acetylated) products. The effect of varying the alkali concentration on the structure and mechanical properties of SPA products is described. Maximum decrystallization is obtained when the swelling is carried out in alkali of intracrystalline swelling strength, prior to treatment with acetic anhydride. Acetylation is instrumental in retaining the highly decrystallized state. The structure of SPA cotton was characterized using chemical analyses, infrared spectroscopy, and x‐ray diffra

ISSN:0021-8995    

DOI:10.1002/app.1977.070210808

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

年代:1977

数据来源: WILEY

摘要:

AbstractThis paper studies the influence of adverse conditions of stress and environment on a conventional industrial two‐coat adhesive system for bonding filled elastomers to steel. Several test methods were used in order to produce rupture at the elastomer/adhesive interface, but even the most stringent stress distributions producedrupture in the elastomerunder relatively rapid constant strain rate testing conditions. However, under fixed strains termed“static fatigue” below immediate rupture conditions,fracture occurred cohesively in the adhesive. This fracture originated in the elastomeric phase of the adhesive. Comparison of elastomer and adhesive creep curves show that the locus of failure depends only upon the ultimate properties of the phase in which fracture occurs. This becomes more complicated for propagation of the fracture because of the influence of rheological, thermodynamic, and morphologic aspects of the other constituents of the assembly.A third type of rupture, produced at the metal surface, was observed by testing under corrosive conditions such as saline solution. Throughout the study, original observations are confirmed for systems using different elastomers, adhesives, or metal surface coa

ISSN:0021-8995    

DOI:10.1002/app.1977.070210809

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

年代:1977

数据来源: WILEY

摘要:

AbstractA model of the action of chemically homogeneous thermal stabilizers of poly(vinyl chloride) is shown. Based on the described computer program and experimental data, the proposed model is confirmed and rate constants of the reaction of stabilizers with HCI and the effect of the products of this reaction on the kinetics of PVC degradation are calculated.

ISSN:0021-8995    

DOI:10.1002/app.1977.070210810

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

年代:1977

数据来源: WILEY