Showing papers by "DSM published in 1987"

Vanadium containing bromoperoxidase: an example of an oxidoreductase with high operational stability in aqueous and organic media.

Abstract: The conversion is described of phenolsulphonephtalein (phenol red) to 3,3',5,5'-tetrabromophenolsulphonephthalein (bromophenol blue) by bromoper-oxidase from the brown alga Ascophyllum nodosum. This reaction provides a convenient assay for the detection of bromoperoxidase activity in vitro. Bromoperoxidase was shown to be stable under turnover conditions for three weeks at room temperature, catalyzing the bromination of phenol red into bromophenol blue. When stored at room temperature in organic sol vents such as acetone, methanol, ethanol [present up to 60% (v/v)], and 1-propanol [40% (v/v)], bromoperoxidase was stable for more than one month. As far as we know this is the first example of an oxidoreductase which displays such great stability. This enhances the applicability of the enzyme in organic synthesis.

Infrared analysis and Izod impact testing of multicomponent polymer composites: polyethylene/ EP D M /filler systems

Abstract: Various multicomponent polyethylene/rubber/filler composites have been characterized by diffuse reflectance infrared spectroscopy (DRIFT) and notched lzod impact testing. This work is part of a study which also included solid state and melt state dynamic mechanical testing of the same composites. The fillers used were an oxidized silicon powder and calcium carbonate. Fillers were also treated with coupling agents gamma -ami nopropyltriethoxysilane (γ-APS) and gamma -methacryloxypropyltrimoethoxysilan8 (γ-MPS). The rubbers were ethylene propylene diene (EPDM) rubber and a maleic anhydride grafted EPDM (EPDM-MA). DRIFT is useful for investigating the structure of these multicomponent composites on the molecular level. The DRIFT technique was used to confirm the presence of γ-MPS in the final composites treated with that coupling agent. The structure of the maleic anhydride functionality of @ maleic anhydride grafted EPDM was also determined. The DRIFT analysis detected a reaction between the maleic anhydride modification of the EPDM and γ-APS during processing on the roll mill to form the cyclic imide structure. This is useful in interpreting a great deal of the dynamic mechanical results. The lzod impact testing shows that impact properties of both the oxidized silicon powder and calcium carbonate composites are improved by rubber addition. The use of EPDM-MA results in greater improvement than EPDM. This is likely due to greater filler-rubber interactions in the case of EPDM-MA which leads to encapsulation of the filler by the rubber due to favourable interfacial interactions. Comparison of the storage modulusG′ at room temperature and lzod impact values was made for the PE/rubber/filler composites and the PE/filler and PE/rubber composites investigated in this study. Proper design of multiconmponent PE/rubber/filler composites may clearly result in higher modulus and higher impact strength than that which is available with two phase PE/filler or PE/rubber systems.

The role of peroxidases, radical cations and oxygen in the degradation of lignin

Abstract: Ligninase is an extracellular peroxidase produced by several species of white-rot fungi. It is able to oxidize methoxylated substrates to radical cation intermediates that can undergo C-H or C-C bond cleavage, thereby providing the basis for the oxidation of veratryl alcohol or degradation of lignin model compounds respectively. In some cases, the radical cation intermediate can act as an oxidant, accepting an electron from a suitable donor. It can thus function as a mediator, causing oxidation in a polymer not immediately accessible to the enzyme. This could be important in the degradation of natural lignocellulose substrates. However, the removal of a single electron by a mediator would leave a radical in the polymer. We propose that oxygen will bind to this radical to generate active oxygen species. This provides a potential mechanism for the auto-oxidation of lignin at a distance from the enzyme. A scheme is presented to account for the observation that ligninase can open the ring of veratryl alcohol.

High-Strength/High-Modulus Structures Based on Flexible Macromolecules: Gel-Spinning and Related Processes

Abstract: Amongst the various developments in the area of high-performance fibres, two major routes can be discerned which are completely different in respect of the starting (base) materials, respectively intrinsically rigid as opposed to intrinsically flexible macromolecules.

Bacterial Culture Collections: Their Importance to Biotechnology and Microbiology

Abstract: (1987). Bacterial Culture Collections: Their Importance to Biotechnology and Microbiology. Biotechnology and Genetic Engineering Reviews: Vol. 5, No. 1, pp. 137-198.

Thermoplastic polymer mixtures

Abstract: New polymer composition which has excellent thermal stability, good impact resistance and processability, containing the following compounds: a) 20-75 wt. % of a graft copolymer which contains 10-90 wt. % rubber and grafted on the rubber a copolymer of acrylonitrile and styrene or α-methylstyrene b) 6-50 wt. % of a copolymer of styrene or α-methylstyrene containing 20-32 wt. % maleic anhydride, with a molecular weight of 50,000-500,000 c) 5-70 wt. % polyamide and d) 0-30 wt. % of a copolymer of styrene or α-methylstyrene and acrylonitrile.

Polyamine-polyene ultraviolet coatings

Abstract: POLYAMINE-POLYENE ULTRAVIOLET COATINGS ABSTRACT Ultraviolet-curable ethylenically unsaturated liquid coating composition are disclosed which consist essentially of: 1- polyethylenically unsaturated material in which the ethylenically unsaturated groups are polymerizable groups which are not (meth)acrylate groups; 2- a polyamine resin, preferably a polytertiary amine resin; and 3- an aryl ketone photosensitizer.

Linear low density polyethylene graft polymers, their preparation and their uses

Abstract: Grafted linear polyethylenes of low density ( ) (LLDPE) and, in particular, having very low density ( ) (VLDPE) and having ultralow density ( ) (ULDPE) and grafted, in particular, with styrene/maleic anhydride are very good impact modifiers which are highly UV resistant and have high toughness and do not cause any discoloration of the polyamides and polyesters modified using them. They are simple and economical to prepare in high conversions. … These polyethylenes are also highly suitable as impact modifiers, adhesives or adhesive coatings, heat-sealing layers, adhesive layers in multilayer films or sheeting, compatibility-increasing agents and adhesion improvers or as components of agents or layers of this type. … Grafted polyethylenes can be prepared by reacting a low-density polyethylene with the graft material at a temperature above 110 DEG C under the action of shear forces using free-radical catalysts and optionally antioxidants, the graft material optionally being employed in the presence of a solvent.

Theoretical treatment of network formation by a multistage process

Abstract: A general scheme for a multistage process of network formation is formulated in which the Galton-Watson or universal consistency relation is assumed to be valid. The scheme is elaborated with the theory of branching processes with cascade substitution. Cyclization is postulated not to occur, substitution effects are allowed and can be incorporated in the probability generating functions (pgf).

Process for removing mercury from organic media

Abstract: The invention is concerned with a process for removing mercury from organic, especially non-polar, media like liquid hydrocarbon mixtures, most preferably natural gas condensates, by contacting the media to be treated with a solid adsorbens, preferably an ion exchange resin, containing active thiol groups. By this method it is possible to remove mercury from the treated media in an amount of more than 97 %.

Ruthenium tetroxide as a staining agent for transmission electron microscopy of polyamide-polyether blends and block copolymers

Abstract: Application de RnO 4 pour colorer la phase caoutchouc amorphe dans le polyamide 6 modifie choc contenant du poly(propeneglycol) comme caoutchouc ajoute

Nonlinear viscoelasticity of polymer melts in different types of flow

Abstract: The nonlinear viscoelastic properties of a fairly large class of polymeric fluids can be described with the factorable single integral constitutive equation. For this class of fluids, a connection between the rheological behaviour in different flow geometries can be defined if the strain tensor (or the damping function) is expressed as a function of the invariants of a tensor which describes the macroscopic strain, such as the Finger tensor. A number of these expressions, proposed in the literature, are tested on the basis of the measuring data for a low-density polyethylene melt. In the factorable BKZ constitutive equation the strain-energy function must be expressed as a function of the invariants of the Finger tensor. The paper demonstrates that the strain-energy function can be calculated from the simple shear and simple elongation strain measures, if it is assumed to be of the shape proposed by Valanis and Landel. The measuring data for the LDPE melt indicate that the Valanis-Landel hypothesis concerning the shape of the strainenergy function is probably not valid for polymer melts.

A study of light scattered by the surface of freely suspended liquid-crystal films

Abstract: An experimental investigation of light scattered by freely suspended liquid-crystal films in the SA and the N phase is reported. Spectral analysis of the scattered light shows the existence of a propagating hydrodynamic mode. An interpretation in terms of surface fluctuations is presented.

The effect of a coupling agent on the viscoelastic properties and internal stresses in high density polyethylene filled with glass spheres

Abstract: It is shown that covalent bonding between high density polyethylene (HDPE) and glass spheres can have a significant influence on the stress relaxation behaviour and the creep properties of the corresponding composites at room temperature. The bonding is obtained by reacting the glass spheres with an azide functional alkoxysilane which is capable of bonding to the HDPE-chain. The internal stress, evaluated from relaxation experiments, increased markedly as a result of this treatment, and it is suggested that the internal stress level reflects the properties of the interphase region between the filler and the bulk matrix and its effect on the viscoelastic properties.

Determination of α-aminonitriles, α-amino acid amides and α-amino acids by means of HPLC, post-column reaction and fluorescence detection

Abstract: An HPLC method was developed for the simultaneous assay of intermediate (α-aminonitrile and α-amino acid amide) and end products (α-amino acid) in process streams of α-amino acid synthesis. Applications are given for Ala, Val and Leu. α-Aminonitriles were stable in a phosphate buffer pH 3, which was subsequently used for sample handling and chromatography. The α-aminonitrile, the corresponding acid amide and α-amino acid were separated using a buffered ion-pair mobile phase on an RP column and were detected fluorimetrically after post-column reaction with fluorescamine. Linearity and precision of the method are given.

Open Tubular Columns and Non-Porous Packings in Copolymer HPLC Analysis

Abstract: The separation of poly(styrene-co-acrylonitrile) is presented in open tubular stainless steel columns and columns packed with non-porous glass beads. Furthermore separation on a short silica packed column proved to be better than on a similar longer column. A definition of the term high performance precipitation liquid chromatography is suggested for gradient elution with sample injection into a starting eluent which is a nonsolvent for the copolymer under investigation. The choice of a suitable solvent-nonsolvent combination is of essential importance.

Ideas about reptation, tube renewal and tube relaxation applied to the description of the non-linear viscoelastic behaviour in shear of some polydisperse polyethylene melts

Abstract: In melts of polydisperse linear polymers like high-density polyethylene (HDPE) the dynamics of a given macromolecule are affected by the renewal of the confining tube owing to movements of surrounding molecules, the more so according as the matrix contains more shorter molecules. At large strains, the relaxation of the tube due to the retraction of matrix molecules also contributes to stress relaxation. For long-chain branched molecules in a polydisperse melt like that of low-density polyethylene (LDPE), the dynamics are dominated by tube renewal and tube relaxation effects. It is argued that for melts of HDPE as well as LDPE the combination of these ideas leads to a rheological constitutive equation consisting of the sum of two integrals. Both integrands are factored into the product of a strain-independent time function and a time-independent nonlinear strain tensor. Using the relaxation spectrum from oscillation experiments and the nonlinear strain measure from first normal stress growth data, this equation satisfactorily describes the decay of the stresses after step strain or after cessation of steady shear flow for melts of two commercial HDPEs and of two LDPEs. For the HDPE samples one integral suffices, but for the LDPE melts the additional time and strain dependences of the integral relating to tube relaxation are indispensable for a good fit of the experimental curves.

Cerium-Molybdenum-Tellurium Oxides

Abstract: Ternary oxide formation in the (Ce, Mo, Te)O system was studied between 400°C and 600°C in air. Eight new phases were observed, namely Ce6Mo10Te4O47, Ce2Mo2Te2O13, Ce4Mo11Te10O59, Ce2Mo2Te4O17, Ce10Mo12Te14O79, Ce6Mo8Te6O45, Ce2Mo3Te2O16, and [Ce4Mo13Te3O51]. Preparative conditions are given and the new compounds are characterized by DTA and TG analyses, X-ray diffraction, infrared, Raman and X-ray photoelectron spectroscopy. Cer-Molybdan-Tellur-Oxide Die Bildung ternarer Oxide im System (Ce, Mo, Te)O wurde zwischen 400°C und 600°C in Luft untersucht. Dabei wurden acht neue Phasen beobachtet (Summenformeln s. Abstract). Die Darstellungsbedingungen und die Charakterisierung der neuen Verbindungen durch DTA, TG, Rontgen-Diffraktion, IR-, Raman- und Rontgen-photoelektronen-Spektroskopie werden angegeben.

Chemical and technical aspects of hydroformylation of olefins with supported liquid-phase rhodium catalysts

Abstract: Supported liquid-phase catalysts containing RhH(CO)(PPH3)3 dissolved in PPH3 are used in the gas-phase hydroformylation of several olefins. Their activity in the hydroformylation of ethylene, propylene and the butenes is reported. Various physicochemical aspects of the rhodium SLP catalysts, such as the adsorptive withdrawal of the rhodium complexes by the supports, the activity of the rhodium complexes at the gas-liquid interface and the solubility of the reactants and products in the liquid part of the catalysts, are discussed. The results are presented of a bench-scale process study of the hydroformylation of propylene, from which the design parameters of a future plant are calculated.

Sheet moulding compound and an upper layer for it

Abstract: The invention relates to a sheet moulding compound (SMC) comprising a basic layer (3) consisting of thermosetting material, fillers, fibres and customary additves, one side of which is provided with two layers, an intermediate layer (2) and a top layer (1), the inter­mediate layer of which lies against the basic layer, the intermediate layer comprising at least fibre reinforcement and thermosetting material in a partly cured state and the top layer comprising the same or a different thermosetting material, which is in a cured state to a smaller extent than the first layer. The invention relates also to a sheet-shaped product that can be applied as an upper layer for a moulding compound like a SMC, BMC and DMC, that consists of the above described intermediate layer and top layer.

Production of high-molecular polytetramethyleneadipamide

Abstract: The invention relates to a method for the production of high-­molecular polytetramethylene adipamide in a two-step process in which the prepolymer particles obtained in the first process step are compressed into pellets which are subjected to the after-condensation reaction. The obtained high-molecular polytetramethylene adipamide pellets can be used without further shaping through e.g. melt extru­sion.