Showing papers by "DSM published in 1988"

Kluyveromyces as a host strain.

Abstract: Kluyveromyces hosts and DNA expression cassettes for use in Kluyveromyces are provided for transcription of endogenous and/or exogenous DNA, and production of peptides, for enhancing production of an endogenous product, or producing an exogenous product. The Kluyveromyces hosts find particular use for secretion of a desired peptide product, where signal sequences may be native to the peptide or provided from endogenous or exogenous signal sequences, including synthetic sequences, functional in Kluyveromyces. A transformation procedure is provided for efficiently transforming Kluyveromyces.

Dna constructs containing a kluyveromyces alpha-factor leader sequence for directing secretion of heterologous derivatives

Abstract: DNA constructs that are useful for providing secretory expression of heterologous polypeptides in yeast comprising a DNA sequence that includes a Kluyveromyces α-factor leader sequence linked to the heterologous polypeptide by a yeast processing signal. Constructs employing the K. lactis α-factor leader and processing signal sequences, with and without spacer, linked to prochymosin are exemplified.

A structural study on solid state drawing of solution-crystallized ultra-high molecular weight polyethylene

Abstract: The influence of solid state drawing of solution-crystallized ultra-high molecular weight polyethylene on the structure has been studied. Results obtained by different wide-angle and small-angle X-ray techniques support a deformation mechanism, which was partially described by Peterlin. An extended mechanism is proposed, which not only explains the orientational effects observed via WAXS and SAXS fairly easily, but can also account for the constancy of the long period, the steady decrease of the meridional SAXS intensity, the increase in crystallinity and the increase in the longitudinal crystallite size as the draw ratio increases (starting from a draw ratio of 10). Furthermore, the observed changes in lateral apparent crystal sizes as well as the stress-strain behaviour during the drawing process can be understood easily in terms of this model.

Method for improving flour dough

Abstract: This invention relates to a method for improving the rheological properties of a flour dough which comprises combining flour, yeast, water and an effective amount of an enzyme preparation comprising sulfhydryl oxidase and glucose oxidase and mixing said ingredients to form a suitable baking dough. The invention results in stronger doughs with improved rheological properties as well as a final baked product with improved texture.

Dynamic-mechanical properties of interfacially modified glass sphere filled polyethylene

Abstract: Model composites of spherical glass particles dispersed in a matrix of high density polyethylene were prepared both with and without interfacial modification by an azidofunctional trialkoxysilane Dynamic mechanical measurements of the composites in the melt state were recorded The unmodified composites behave as theoretically predicted and the effect of particle—particle interaction at high volume fractions can be measured The composites with a modified interfacial region have greater shear moduli due to the effect of a region surrounding the particle modified by the silane The material in this region is largely bound to the glass surface and was examined by Fourier transform infrared spectroscopy after extraction of the bulk matrix Theoretical calculations are shown to be useful in calculating the mechanical properties and volume fraction of the interfacial region

Modeling of Extrusion With Slip Boundary Conditions

Abstract: Slip at boundaries is possible in viscous flows; for instance, in the extrusion of foodstuffs, water-containing materials, and some polymers. There are two phenomenological descriptions of slip: The first is based on the presence of a very thin, low viscosity boundary layer and has been derived for capillary flow and extrusion; the second is based on a Coulomb-friction mechanism and has been derived for capillary flow only. After a survey of these results, the friction model is derived for the extrusion process. All calculations are as simple as possible: two-dimensional, Newtonian, isothermal, and with constant boundary layer parameters of coefficients of friction. A strong dependence of pumping characteristics and efficiency on the slip boundary conditions, and also on the extruder length in the case of friction, was found, especially when slip is only allowed for at the screw surface. Exercises like these may help in understanding abnormal extrusion behavior of slippery materials in practice.

An experimental and theoretical study of the effect of the elongational history on the dynamics of isothermal melt spinning

Abstract: Isothermal spinning of a low-density polyethylene (LDPE) melt has been compared with isothermal creep under a constant force. Although the same initial stress was applied in both measurements, there was a tremendous difference in the stretch ratio vs. time curves, which demonstrates the enormous effect the flow before and in the capillary has on the rheological behaviour of a polymer melt. The modelling of the upstream flow as a plug flow with velocity inversely proportional to the square of the channel radius has been the basis of the development of a computer program incorporating the effect of the prehistory on the velocity profile during spinning. The constitutive equation used was a well tested, single integral constitutive equation containing a memory function and a nonlinearity function. The calculated results have been compared with isothermal spinning data for various boundary conditions. The agreement between calculation and experiment is encouraging and indicates the importance of the elongational component in the upstream flow.

Controlling and monitoring interfacial reactions in composites of azidosilane modified glass filled polyethylene

Abstract: Model composites of spherical glass particles dispersed in a matrix of high density polyethylene were prepared with controlled variations in the interfacial structure. Dynamic-mechanical measurements of the composites in the melt state were recorded. The physical properties are found to relate to the morphology, bonding, reactivity, and other characteristics of the interfacial region which can be controlled by the applied chemistry. The interfacial reactions can be monitored in-sity by dynamic-mechanical analysis and differential scanning calorimetry.

Morphology and rheological properties of polypropylene‐linear low density polyethylene blends

Abstract: The dynamic shear viscosity and the morphology of polypropylene homopolymer and copolymer blended with linear low density polyethylene are studied. A maximum in the dynamic shear viscosity vs. blend composition is reported for the polypropylene copolymer, linear low density polyethylene system. The increasing dynamic shear viscosity is in accordance with the occurrence of a morphology of polyethylene inclusions in rubber surrounded by a polypropylene matrix. Comparing calculations of the dynamic shear viscosities—based on a shell model with interlayer—and experimental results supports this view.

Polyolefin foams having open and/or closed pores and consisting of polyolefins of ultrahigh molecular weight, process for their production, and their use

Abstract: The invention relates to polyolefin foams consisting of polyolefins of ultrahigh molecular weight, i.e. weight-average molecular weight from about 4×105 to 6×106 g/mol and higher, and to a novel process for producing these foams by foaming a solution of a polyolefin of ultrahigh molecular weight in a solvent with the use of a physical or chemical blowing agent or of an inert gas blown into the solution, and cooling of the resulting foam to a temperature below the gelling temperature of the polyolefin. If appropriate, these foams can be provided wholly or partially with a smooth skin on their surface by superficial cooling, if appropriate under the action of pressure. These foams are distinguished by high tensile strength and impact strength values, shock-absorbing properties, low glass transition temperatures, low embrittlement at low temperatures and high chemical resistance, and they are used especially as mechanical and acoustic insulating materials, materials of construction, filter agents and implantation materials.

Butyl rubber/polypropylene elastoplastic

Abstract: The present invention provides an elastoplastic composition comprising a butyl terpolymer rubber and polypropylene, which composition is characterized by being treated with a peroxide curing agent.

Thermodynamics of polymer solutions and blends

Abstract: Etude generale: methodes d'etude des equilibres de phase de systemes de polymere; discussion des modeles thermodynamiques d (modele FHS), prediction au 4eme niveau, influence de la pression, cas des melanges de copolymeres statistiques

Mesophases in mixtures of water and polyoxyethylene surfactant: variations of repeat spacing with temperature and composition

Abstract: Lamellar (L α ) and hexagonal (H 1) mesophases, formed in mixtures of water and polyethylene oxide (PEO) oleylethers (average EO-numbers 5 (a), 8.5 (b) and 14 (c)) and pure hexaoxyethylene dodecylether (d), were investigated with small-angle X-ray diffraction. Analysis of repeat spacings shows a deviation from linear one- and two-dimensional swelling ofL α andH 1, respectively, when a transition to a mesophase with a larger curvature of the interface is approached. With regard toL α , in this respect similar behaviour is observed for a pure surfactant (d) and a surfactant with an EO-length distribution (b). It is proposed that, through the formation of aggregates of limited extent, water filled pores in the mesophases arise. This is confirmed by analysis of the intensity ratio of diffraction maxima of first and second order inL α . Models for finite aggregates are introduced. These consist of (1) lamellae, infinite in one direction and with variable lengthL in a direction perpendicular to the first, with cylindrical edges and (2) cylinders with variable lengthL bounded by spherical caps. According to these models, under certain conditions, finite aggregates may be formed without an increase of the interfacial area per surfactant molecule. Applying the models to the regions where non-linear swelling is observed, reasonable values forL are found, which decrease progressively when the phase transition is approached.

Process for the production of thin stretched films from polyolefins of ultrahigh molecular weight

Abstract: The invention relates to a process for the production of thin stretched films with thickness between 0.1 and 20 µm from polyolefins of ultrahigh molecular weight by dissolving the polyolefin in a solvent, shaping the solution at a temperature above the solution tem­perature of the polyolefin to a tape, cooling the tape to a tem­perature below the solution temperature to obtain gelation and stretching the gelled tape. In this process the gelled tape is ini­tially subjected to a preliminary orientation in one direction, under solvent removal, and is then stretched in a direction essentially per­pendicular to the direction of preliminary orientation, at elevated temperature, followed by final stretching to obtain the finished thin films. This process makes possible the production of films which are free from pores, that is to say transparant and which posses high Young's moduli, high tensile strengths and favourable values for elongation at break.

Interfacial effects on the melt state behavior of polyethylene-EPDM-calcium carbonate composites

Abstract: Dynamic mechanical spectra of various composites of high density polyethylene (PE), ethylene propylene diene rubber (EPDM), and calcium carbonate were obtained at 190°C with a parallel plate instrument. Interfacial effects were found to have a significant influence on the dynamic mechanical behavior of these composites.

Polyamide resin composition

Abstract: PURPOSE: To obtain composition used as useful material in heat-resistant field having steeply improved thermal conductivity and heat distortion temperature comprising nylon 46 resin, heat-conductive filler and reinforcing material CONSTITUTION: (A) Nylon 46 resin is mixed with (B) a heat-conductive filler and (C) a fibrous reinforcing material A fibrous material or powdery material selected from the group consisting of alumina, silicon nitride, magnesia, boron nitride, aluminum nitride and ceramic fiber is used as the component B and an amount of 30-70wt% is added Alumina short fiber composed of 60-98wt% alumina and 2-40wt% silica or alumina silica short fiber composed of 40-60wt% alumina and 40-60wt% silica is used as the ceramic fiber in the component B and an amount of ≥5wt% is mixed COPYRIGHT: (C)1991,JPO&Japio

Thermoplastic elastomer mixture

Abstract: The invention concerns a thermoplastic polymer mixture based on a polyamide and a graft copolymer of a copolymer of a vinyl aroma­tic compound and acrylonitrile in a rubber, on the rubber being moreover present monomers of a vinylaromatic compound and of a carboxy- and/or imide-containing compound in a relative molar ratio of 5 : 1 to 1 : 5. It was found that the mixture of both components showed superior mechanical properties, and is easy to process.

Core-level XPS-spectra of fluorinated polyethylene: An ab initio study

Abstract: Ab initio calculations have been carried out on the fluorinated butanes, a model system for fluorinated polyethylene. Geometries were optimised with STO-3G and 4-31G basis sets, whereas single point calculations were also performed using double-zeta+polarisation basis sets. The C 1 s core-level energies were obtained by applying Koopmans' theorem. The effects of basis set size and geometry dependence on the ionisation energies were studied in detail. Both primary and secondary substituent effects of the fluorine atoms on the C 1 s levels were calculated and compared with experimental data. It was concluded that a 4-31G basis set yields Koopmans'values for the C 1 s shifts in binding energy in good agreement with experiment.

Process for high-temperature (co)polymerization of ethylene

Abstract: Catalyst system, suitable for the (co)polymerization of ethy­lene and optionally minor amounts of 1-alkenes and/or dienes at a tem­perature of at least 180◊C, to be prepared by combining at least two components A and B, which components comprise: A : one or more titanium compounds, one or more vanadium com­pounds, one or more aluminium compounds, one or more magne­sium compounds and optionally one or more halogen compounds, in such amounts that the atomic ratio of magnesium to the sum of titanium and vanadium is between 0 and 10, the atomic ratio of aluminium to the sum of titanium and vanadium is at least 3, the atomic ratio of aluminium to magnesium is at least 1, and the atomic ratio of halogen to magnesium is at least 2, B : one or more organoaluminium compounds, which two components are, separately or in combination, supplied direct to the polymerization vessel.

The determination of the lamellar thickness in semi-crystalline polymers by small-angle scattering

Abstract: Etude comparative de 3 methodes de mesures de l'epaisseur lamellaire par diffusion RX centrale basees sur l'observation de la periode d'identite pour l'une, la mesure de la surface specifique de la limite de phase pour la seconde et sur l'analyse de la forme du pic pour la 3eme. Discussion des conditions d'application de ces methodes et des types de moyennes obtenues. Presentation de resultats experimentaux

Investigation of the intramolecular structure of styrene−ethylmethacrylate copolymers by 1H- and 13C-NMR: reassignment of 1H-NMR spectra

Abstract: The compositions and sequence distributions of homogeneous styrene (S)–ethyl methacrylate (E) copolymers, obtained by low conversion solution polymerization have been studied by 1H- and 13C-NMR. A new set of peak triad assignments was proposed for the δ 2.1–4.2 ppm region in the 1H-NMR spectrum, whereby the reactivity ratios of rS = 0.59 and rE = 0.50 were used to establish this new assignment. The EEE and SSS blocks, present in these copolymers, have a high degree of syndiotacticity (σEE = 0.23, σSS = 0.39), whereas the ESE units are exhibiting a slight tendency toward isotacticity (σES = 0.66).

The influence of water on the oxygen–silver interaction and on the oxidative dehydrogenation of methanol

Abstract: Experiments carried out using temperature-programmed desorption and reduction could detect no interaction between water and silver at 200 °C. However, separate experiments on the effect of water on the oxidative dehydrogenation of methanol over a silver catalyst showed that water affected the selectivity of the reaction, reducing the production of CO2. It is suggested that this change in selectivity arises from the adsorption of water on the weakly bound oxygen surface species which are responsible for the non-selective reaction to CO2. The interaction is apparently too weak to give rise to observable species in the t.p.d. and t.p.r. experiments.

Glass formation in the TeO2-MoO3-CeO2 system

Abstract: Glass formation in the TeO2MoO3CeO2 system was investigated and low melting stable glasses with up to 30 mole-% CeO2 were synthesized. Infrared spectral investigations were used to develop structural models for the vitreous ternary system. CeO2 mainly acts as a modifier without affecting appreciable changes to the glass network and coordination of the glass formers. Glasses in the molybdenum-rich compositional range are mainly composed of [MoO6] and [TeO3] polyhedra, whereas low MoO3-containing glasses consist of [TeO4] groups and isolated [MoO4] units. On the whole, the basic structural polyhedra participating in the formation of the three-dimensional glass forming network are therefore [TeO4], [TeO3], [MoO6], [MoO4], and [Mo2O8] (or [MoO5]) units. The structural affinity of some ternary glasses to crystalline Ce4Mo11Te10O59 is pointed out. The high electrical conductivity of the ternary glasses is interpreted on the basis of electron hopping between transition ions in different valence states and contributions due to the Te(IV) network. Glasbildung im TeO2MoO3CeO2-System Untersucht wurde die Glasbildung im TeO2MoO3CeO2-System, und es wurden niedrigschmelzende stabile Glaser mit bis zu 30 mol-% CeO2 synthetisiert. Infrarot-Spektraluntersuchungen wurden zur Entwicklung von Strukturmodellen fur ternare Glaser angewandt. CeO2 wirkt in erster Linie als Modifiziermittel und verursacht keine nennenswerten Anderungen im Glasnetzwerk und in der Anordnung der Glasbildner. Die molybdanreichen Glaser sind hauptsachlich aus [MoO6]- und [TeO3]-Polyedern zusammengesetzt, wogegen Glaser mit niedrigem MoO3-Anteil aus [TeO4]-Gruppen und isolierten [MoO4]-Einheiten bestehen. Insgesamt gesehen sind die an der Bildung des dreidimensionalen glasbildenden Netzwerks beteiligten Polyeder daher [TeO4]-, [TeO3]-, [MoO6]-, [MoO4]- und [Mo2O8]- (oder [MoO5])-Einheiten. Die strukturelle Affinitat einiger ternarer Glaser zu kristallinem Ce4Mo11Te10O59 wird gezeigt. Die hohe elektrische Leitfahigkeit der ternaren Glaser wird auf der Grundlage des Elektronensprunges zwischen den Wertigkeitsstufen der Ubergangsmetallionen und Anteilen des TeIV-Netzwerks interpretiert.

Process for the preparation of benzaldehyde in the gas phase

Abstract: The invention relates to the preparation of a benzaldehyde by hydrogenation of a corresponding benzoic acid in the gas phase in the presence of a manganese containing catalyst on an acid carrier. The invention is characterized in that use is made of a catalyst prepared by: a) coprecipitation, at a pH between 7 and 10, of a manganese salt and a salt from which an acid carrier is formed, b) subsequent calcination at a temperature between 300 and 700°C, c) followed by reduction with a hydrogen containing gas mixture. Preferably the catalyst contains oxides of aluminium, zirconium, titanium, hafnium and/or niobium.

Process for producing moulded articles

Abstract: The invention relates to a process for producing moulded articles with apertures by cutting a sheet-shaped product comprising a thermosetting resin, fillers and fibrous material into a desired shape, laying it in a mould and curing it at elevated temperature and pressure, the process being characterized in that the sheet-shaped product is divided into strips and that a plurality of strips are placed with overlap around the aperture together in a desired amount by an automatically controlled machine, the desired amount by weight is reached by adjusting the lengths of the strips.