摘要:

AbstractThe copolymers of methyl methacrylate and ethyl methacrylate containing ferric chloride were prepared with varying compositions and subjected to Mössbauer studies. Mössbauer spectra show no reduction of ferric species to ferrous during the polymerization process. The Mössbauer parameters show the irregular environment around the ferric ion. The TGA studies show the thermal stabilizing behavior of ferric chloride in copolyme

ISSN:0021-8995    

DOI:10.1002/app.1987.070330501

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe behaviors of iron, nickel, and zinc dialkyl dithiocarbamates were compared with the corresponding thiuram disulphide in their reaction with cumene hydroperoxide (CHP) at 110°C. The metal complexes exhibit both homolytic and heterolytic processes and transformation products formed during the above reactions and not the initial metal complexes were found to be responsible for the heterolytic decomposition process. However, the nature of the initial transformation products in the case of the iron and nickel complexes differed from those of the corresponding zinc complex. In the former case the corresponding disulfide was shown to be the initial transformation product while there was no evidence for the formation of disulfide in the case of the zinc complex. This difference appears to be responsible for the observed different kinetic behavior of CHP decomposition in the presence of the nickel and iron complexes from that in the presence of zinc. This thiuram disulfide behaves quite differently from the metal complexes in that heterolytic decomposition of hydroperoxide predominates at all molar ratios of the disulphide to the CHP. The hydroperoxide decomposition curves in this case show only one step in contrast to the metal complexes which show a multistep behavior, and this was shown to correspond to the third catalytic stage in the reaction of the metal complexes. Comparison of the rate constant of this step with that of the final step of the metal complexes shows a close resemblance to the case of the iron and nickel and is quite different from that of the zinc complex, confirming the intermediacy of the disulfide in the former cases but not in the latter

ISSN:0021-8995    

DOI:10.1002/app.1987.070330502

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

年代:1987

数据来源: WILEY

摘要:

AbstractReduced (4‐O‐methyl‐D‐glucurono)‐D‐xylan and nine methylglycosides related to this polysacharide were studied by dynamic and isothermal thermogravimetry. It could be stated from the results that the thermal stability of saccharides is increasing with increasing number of pyranose units. The models related to (4‐O‐methyl‐D‐glucurono)‐D‐xylan are more thermally stable than the corresponding hexoglycanic models. Rates of gasification of models containing uronic acid methylesters are higher than those of neutral methylglycosides. The rate of polysaccharide gasification was the highest one from all models studied. The supramolecular structure of polysaccharide is dramatically influencing the course

ISSN:0021-8995    

DOI:10.1002/app.1987.070330503

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

年代:1987

数据来源: WILEY

摘要:

AbstractA graphic multiple peak resolution method by wide angle X‐ray scattering (WAXS) pattern was described and used to estimate the interplanar spacings, crystallinities, and crystalline sizes of eight poly(ethylene terephthalate) (PET) fibers. The values for interplanar spacings of Dacron 54 suggested that the unit cell model by Daubeny et al. was appropriate for Dacron fibers. In general, crystallinities of the eight PET fibers ranged from 44.7% for Dacron 54 to 62% for Dacron 56 with the copolymers in between. Crystallinity by density measurements was determined and compared to that by WAXS in both fabric and ground fiber forms. Crystallinity values for each fiber derived by these three methods were different. For each fiber, crystallinity was lowest by WAXS in the ground fiber form, followed by the density measurement and WAXS in the fabric for

ISSN:0021-8995    

DOI:10.1002/app.1987.070330504

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

年代:1987

数据来源: WILEY

摘要:

AbstractPoly(butadiene–maleic anhydride) was aminated with methoxypropylamine. Although this reaction product (APBM) was easily soluble in water, when APBM was supported on activated alumina, APBM/alumina hybrid materials (HM) removed dodecylbenzenesulfonate (DBS) solutes in water. The effects of the supported amounts and of the initial concentrations of DBS on the removed amounts were studie

ISSN:0021-8995    

DOI:10.1002/app.1987.070330505

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

年代:1987

数据来源: WILEY

摘要:

AbstractAn analysis has been carried out of the two‐dimensional elongational flow in an impinging channel geometry having either straight or converging wall downstream ducts. Numerical solutions for Stokes flow were obtained using a nonorthogonal transformation of variables which converts the system to a square grid geometry. Calculations show that a strong extensional flow exists from the point of channel impingement to a distance downstream approximately D/4 where D is the channel depth at the impingement point. Extensional gradients and total fluid strains also increase when the downstream duct is convergent as opposed to being straight. An experimental analysis of the velocity field in the former geometry demonstrates that, under slow flow conditions, the kinematics of a Newtonian and a highly non‐Newtonian fluid become indistinguishable in the downstream region. The latter observation is shown to be consistent with second‐order fluid theory and the Giesekus‐Tanner

ISSN:0021-8995    

DOI:10.1002/app.1987.070330506

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

年代:1987

数据来源: WILEY

摘要:

AbstractIt was studied how to localize carboxyl groups at the particle surface in a preparation of styrene (S)/butyl acrylate (BA)/methacrylic acid (MAA) polymer emulsion. The relative distribution of carboxyl groups in the emulsion was determined by conductometric titration method: in serum, at surface, and inside particle. By seeded (two‐stage) emulsion polymerization that S–BA–MAA terpolymer emulsion was first prepared at low pH and then second stage polymerization of S–BA was continued at high pH, S/BA/MAA polymer emulsion particles in which carboxyl groups are localized predominantly at the surface could be p

ISSN:0021-8995    

DOI:10.1002/app.1987.070330507

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

年代:1987

数据来源: WILEY

摘要:

AbstractUnderstanding the deformation behavior of an amorphous thermoplastic, e.g., poly(ethylene terephthalate) (a‐PET) and one of semicrystallinity, viz.,i‐PP, can be is of both fundamental and practical importance. Much has been done to study the influence of temperature and strain, but not the influence of deformation conditions on the three‐dimensional orientation of many thermoplastic. In this study we consider the incremental effect of hydrostatic pressure and process geometry on strain‐induced deformation.a‐PET has been free drawn (i.e., no hydrostatic pressure) isothermally on a tenter frame device. The hydrostatic, equibiaxial deformation was achieved by a forging process involving squeezing between two circular plates. These two processes have been carried out at a series of deformation rates, with the three‐dimensional refractive index measurements having been made on the PET andi‐PP films using a modified Abbe refractometer, as per Samuels. The reported trirefringence measurement provides a sensitive scale for the plana

ISSN:0021-8995    

DOI:10.1002/app.1987.070330508

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe sorption of propane in poly(ethyl methacrylate) was investigated above and below the polymerTgand the dual‐mode sorption model parameters were evaluated. The Langmuir capacity decreased as the temperature was raised toTgand the apparent Henry's law constant exhibited a discontinuity atTg. The enthalpy of microvoid filling ΔHHis more exothermic than the enthalpy of dissolution atT

ISSN:0021-8995    

DOI:10.1002/app.1987.070330509

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

年代:1987

数据来源: WILEY

摘要:

AbstractThermal analyses (TG, DTG, and DSC) of cellulose treated with diammonium phosphate or boric acid were conducted in atmospheres of differing oxygen concentration (N2, and 2.5, 10, 21% O2in He). The weight loss process from both untreated and treated cellulose consists of a first, slow stage, a second, rapid stage, and a third, prolonged, char oxidation stage. The first two stages appear to be first‐order reactions; their Arrhenius parameters were obtained. Both of the additives accelerate the beginning of the weight loss, increase the char yield, and inhibit the char oxidation. Boric acid inhibits the first stage and ammonium phosphate promotes it. The effects of oxygen are smaller than those of the additives. Oxygen produces three effects: acceleration of the beginning of the weight loss, an increase in the char yield, and oxidative gasification of the char. However, the dominant of these three effects changes depending on the oxygen concentration. The main weight loss and the char yield for untreated and treated cellulose may be explained by a chain reaction consisting of random‐scission initiation, depropagation producing levoglucosan, and grafting termination, all describable by Arrhenius kinet

ISSN:0021-8995    

DOI:10.1002/app.1987.070330510

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

年代:1987

数据来源: WILEY