Rationalized Load and Lifetime of Brittle Materials

The design and testing of structural parts from materials which exhibit subcritical crack growth can be improved by introducing auxiliary quantities into the classical concepts of fracture mechanics. The equivalent static stress, equivalent loading time, standardized loading time, and standardized lifetime, as well as the decrease in lifetime and residual lifetime, are defined, with examples of their application.     

Fast determination of fatty acids in oil-utilizing resins by NMR spectroscopy

This work describes the determination of oil either as such or in oil-utilizing resins such as alkyds and urethanes, by means of NMR techniques. Both the qualitative and quantitative analyses are demonstrated and the accuracy is assessed. Typically, the complete analysis of an alkyd resin takes less than 1 hr.     

Refractive index increments of polyethylene

The refractive index increments of linear and branched polyethylene were determined for several solvents and various wavelengths (403, 436, 546, and 633 nm), mainly at 135°C. Differences were observed between values for linear and branched samples. Data obtained in this investigation are compared with the reported ones.     

Reactive polymers,XXXVII. An investigation of the internal structure of polymeric sorbents based on poly(2,3-epoxypropyl methacrylate-co-ethylene dimethacrylate)

The internal structure of polymeric sorbents based on 2,3-epoxypropyl methacrylateethylene dimethacrylate was investigated by means of mercury porosimetry and by employing the sorption method. The results were confronted with characteristic chromatographic data and helped to elucidate the relationships existing between the internal structure of copolymers and their chromatographic properties.     

Numerical study on the spectroscopic ellipsometry of lamellar gratings made of lossless dielectric materials

The spectroscopic ellipsometry of lamellar gratings made of lossless dielectric materials is studied numerically by using the rigorous coupled-wave method with the use of Li's Fourier factorization rules [J. Opt. Soc. Am. A 13, 1870 (1996)], which are known to improve the convergence on the analyses of metallic gratings. Numerical results show that the calculation method also provides fast convergence on lossless gratings, and accurate values of the ellipsometric angles are obtained in very short computation times. Moreover, estimation of grating parameters is investigated by using a cost function defined by the average distance on the Poincaré sphere, and it is shown that the computation required for accurate estimation is possible in reasonable computation time.     

Die polymerisation der lactame VI. Die copolymerisation von 6-caprolactam und 8-capryllactam

The process of incorporating 6-caprolactam and 8-capryllactam into polymer chains was studied during the hydrolytic, cationic, and anionic copolymerization in the case of equimolar ratio of the above mentioned monomers. At the beginning of the hydrolytic copolymerization at temperatures between 200 and 260°C, 6-caprolactam was more rapidly incorporated into the chains. Decreasing temperature led to a decrease in the total rate of polymerization with increasing difference between rates of incorporating the two components. Contrary to this, at the initial stage of the cationic copolymerization, the incorporation of 8-capryllactam was faster by orders of magnitude than that of 6-caprolactam, the changes of the copolymer composition being independent of temperature. Under the conditions of interest, in the course of the anionic copolymerization the two monomers were characterized with the same rates of incorporation into the polymer chains. Different melting points of products separated at various stages of the copolymerization process corresponded to the above mentioned differences in rates of incorporating individual monomers into polymer chains when different reaction mechanisms were employed.     

Reaktive Polymere. II. Die Herstellung von Metallchelaten vernetzter Polymerer

The reaction of bivalent ions (Cu, Co, Zn, Ni) with ethylene diamine bounded to homogeneous crosslinked terpolymer glycidyl methacrylate-styrene-divinylbenzene or macroporous copolymer glycidyl methacrylate-ethyleneglycole dimethacrylate has been studied. The capacity of polymer sorbent, exchange ability and the kinetic of the reaction has been studied.     

Kinetics of sorption and desorption of HCl and low molecular weight organic acids by styrene and acrylic weak base resins

Several important parameters for the operation of ion exchange resins in water treatment, such as breakthrough capacity, maximum flow rate, efficiency and reversibility of organic matter sorption and desorption, exhibit a close connection with the ion exchange rate. Therefore this value, expressed as the exchange half-time(l_0,5) can be used as a criterion for a proper resin type choice and can also help to judge its use for obtaining treated water of required composition.The sorption and desorption rates of HCl, caproic acid and sulfosalicylic acid by styrene and acrylic weak base resins were estimated and the results obtained with particular resins were compared. Attention has been paid to the effect of gelular and macroporous matrix and solution concentration. Acrylic resins are preferable for sorption and desorption of HCl at low concentrations, at higher concentrations macroporous-styrene resins are better. Sorption of low-molecular organic acids is primarily controlled by selectivity and proceeds faster on acrylic resins at all concentrations. Desorption is governed by the concentration of the elution solution, rather than by selectivity and occurs faster on macroporous styrene resins. The macroporous matrix generally has a substantially smaller kinetic advantage for acrylic than for styrene weak base resins.     

Polymerization of lactams, 38. Copolymerization of 6-caprolactam with some of its non-homopolymerizing derivatives

It was demonstrated that non-homopolymerizing derivatives of 6-caprolactam: 7-cyclohexyl-1-aza-2-cycloheptanone (I) and 7-isopropyl-5-methyl-1-aza-2-cycloheptanone (II) were polymerizing with 6-caprolactam under conditions of the socalled hydrolytic polymerization. With its increasing content in the initial reaction mixture the copolymerization rate, the equilibrium content of the copolymer, and the reduced viscosity decreased. Lactam (I) was a more reactive comonomer in comparison with lactam (II).     

Antioxidantien und Stabilisatoren XXVIII. Gelchromatographie nichtflüchtiger phenolischer antioxidantien zur stabilisierung von polymeren

High resolution gel chromatography was applied to the analysis of phenolic antioxidants mixtures formed by an alkylation of 4,4'-isopropylidenebisphenol and used for the stabilisation of polyolefins and rubbers. The calibration by pure model substances provided values of relative zone rates on S-GEL-832 for a series of tert-butyl and tert-octyl derivatives of phenol and 4,4'-isopropylidenebisphenol. The chromatograms show in some cases a separation of isomers differing in size of their molecules in solution.