Kautschuke

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Kautschuke

Performance of Polyamide Journal Bearing Including Thermal Expansion Effects

An analytical technique to predict the performance of journal bearing is proposed, which considers the elastic deformation of bearing surface caused by hydrodynamic pressure and thermal expansion. The results show that the maximum temperature of bearing surface increases significantly with decreasing clearance ratio. This is more pronounced for polyamide bearing compared with lead and steel […] mehr...

28.April 2003 - Neues aus der Forschung

Kautschuke

Kaltmastikation hydrierter Nitrilkautschuke

Bei Untersuchungen zur Kaltmastikation von technischen hydrierten Nitrilkautschuken mit einem Acrylnitrilgehalt von 34 bis 43 Gew.-% wurde gefunden, daß sich diese Kautschuke durch Wirkung mechanischer Scherkräfte abbauen lassen. Nach ausreichend langer Mastikationszeit wird bei allen Kautschuken eine Grenzmolmasse Mn,lim = 58,5 bis 66,5 kg/mol erreicht. Sowohl die Geschwindigkeit der Molmasseabnahme als auch der Abbaugrad hängen […] mehr...

28.April 2003 - Neues aus der Forschung

Additive & Füllstoffe

Influence of the Blend Composition in the Internal Friction of NR/SBR Compounds

Mechanical dynamic measurements were used in this work to analyze the behavior of cured, carbon black-filled NR/SBR blends using a sulfur/accelerator system. The loss tangent (tan δ) of the compounds was studied in the frequency range between 10−3 and 10 Hz and temperatures between 80 and 260 K. Measurements were performed with an automated sub-resonant […] mehr...

28.April 2003 - Neues aus der Forschung

Kautschuke

Ethylene-1-octene Polyolefin Elastomers

Since commercially launched the impact modification of PP has grown to one of the major applications for ethylene-1-octene polyolefin elastomers (Engage). Available in free flowing pellet from ethylene-1-octene polyolefin elastomers offer excellent processing and handling properties. It was found that using ethylene-1-octene copolymers gives improved performance of elastomer modified PP (TPO) in terms of impact […] mehr...

28.April 2003 - Neues aus der Forschung

Kautschuke

Purified Refinery Sludge as Process Aid in Sulphur Vulcanization of Natural Rubber

This paper reports the data obtained on an attempt at the utilisation of the sludge which is a dumped waste of petroleum refineries. This sludge after purification was used as a processing aid in the sulphur vulcanization of natural rubber where carbon black is used as filler. Different mixes, containing varying concentrations of aromatic oil/refinery […] mehr...

28.April 2003 - Neues aus der Forschung

Additive & Füllstoffe

Improving the Heat Resistance of Hydrogenated Nitrile Rubber Compounds – Part 2: Effect of a Novel Heat Stabilizer Additive on the Heat Resistan

Under aerobic hot aging conditions, hydrogenated nitrile rubber compounds undergo crosslinking reactions that lead to embrittlement and ultimately to failure. Often the useful lifetime of an article, at a given service temperature, is assessed by determining the time required for a particular property of interest to degrade to a critical value. A novel heat stabilizer […] mehr...

28.April 2003 - Neues aus der Forschung

Kautschuke

Monitoring Thermal Oxidation of Sulfur Crosslinks in SBR- Elastomers using Sulfur K-edge XANES: A feasibility study

Sulfur K-edge X-ray Absorption Near Edge Structure (XANES) measurements were used to monitor the processes occuring at the sulfur-crosslinks during high temperature oxidative aging for a number of SBR compounds. Variations included sulfur links of different type and density, filler material and use of antidegradants. We find a general mechanism of the aging process which […] mehr...

28.April 2003 - Neues aus der Forschung

Kautschuke

Characterization of Crack Toughness Behaviour of Unfilled and Filled Elastomers

Elastomer materials are used in a wide application range and are subjected to different loading from which material failure results. Because this failure is caused by initiation and propagation of cracks, application of fracture mechanics methods for material assessment is obvious. A short summary of possibilities for crack resistance curve determination, including alternative methods, is […] mehr...

28.April 2003 - Neues aus der Forschung

Kautschuke

Acrylonitrile Butadiene Rubber and High Styrene Resin

The rheological behaviour of composites based on acrylonitrile butadiene rubber (NBR) and high styrene resin (HSR) has been studied by using a Monsanto Processibility Tester. All the systems show pseudoplastic flow behaviour. It has been observed that the die swell increases with an increase in shear rate and decreases with an increasing wt % of […] mehr...

28.April 2003 - Neues aus der Forschung

Kautschuke

Thermal Stability, Swelling Behaviour and Dielectric Properties of NBR/PVC-PVAc Blends

Blends of butadiene-acrylonitrile-rubber (NBR) and vinyl chloride/vinyl acetate copolymer (PVC/PVAc) were prepared in various ratios. The viscosity measurements and scanning electron microscopy revealed that NBR and PVC/PVAc copolymers are compatible in all ratios. Comparative studies of the curing characteristics of such blends as well as physico-mechanical properties, swelling behaviour and dielectric measurements of their vulcanizates […] mehr...

28.April 2003 - Neues aus der Forschung

Kautschuke

Electrochemical Evidence of Transitory Ionic Species in the Vulcanization of Natural Rubber with Sulfur – 2-Mercaptobenzothiazole and Zinc Oxide

Continuous low level current (CLLC) measurements are used to investigate the vulcanization of natural rubber (NR) with sulfur (S), 2-mercaptobenzothiazole (MBT) and zinc oxide (ZnO) in the presence and absence of stearic acid (StAc). At elevated temperatures, the mixtures show increased conductivity attributable to the presence of ions. Current curve maxima characteristic of transitory ionic […] mehr...

28.April 2003 - Neues aus der Forschung

Kautschuke

Eigenschaftsmodifizierung von Polypropylen durch Copolymerisation mit höheren α-Olefinen

Mit einem isospezifischen Metallocen-Katalysator wurden Propen/α-Olefin-Copolymere mit Comonomergehalten bis 15 Mol-% synthetisiert. Es erfolgte eine Charakterisierung der Produkte hinsichtlich ihres thermischen und mechanischen Verhaltens. Von Interesse war neben der Möglichkeit der Modifizierung der Eigenschaften von Polypropylen die Untersuchung des Einflusses unterschiedlich langer Alkyl-Seitenketten, die durch Copolymerisation von Propen mit linearen und verzweigten α-Olefinen eingeführt werden. […] mehr...

28.April 2003 - Neues aus der Forschung

Additive & Füllstoffe

Investigations on the Use of Protective Coating Material as an Antiozonant for Natural Rubber under Static Deformation

The following study was set to investigate the effectiveness of a liquid nitrile-butadiene rubber coating, applied as an antiozonant for natural rubber under static conditions. Two natural rubber compounds were used, one with a combined system of a specified wax and a chemical antiozonant and the other without any antiozonant additives. The liquid rubber material […] mehr...

28.April 2003 - Neues aus der Forschung

Kautschuke

Rubber/Filler Compound Systems in Powder Form

With the development of a silica-loaded free-flowing rubber/filler compound system based on E-SBR it could be demonstrated that the powder rubber technology can also be successfully used for white fillers. For this, the addition of bi-functional sulphur-containing organosilanes for rendering the silica surface hydrophobic plays a vital role. During drying of the powder rubber, a […] mehr...

28.April 2003 - Neues aus der Forschung

Kautschuke

The Paradoxical Nature of Natural Rubber

The green nature of natural rubber is widely accepted, yet it is probable that many remain unaware of the significant contribution which natural rubber makes to global ecology. On the other hand, it can be argued that the main market for natural rubber (truck tyres) is a major contributor to destruction of the environment. Clearly […] mehr...

28.April 2003 - Neues aus der Forschung

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