Various elastomers are used for automotive components because of their physical properties, chemical properties, durability, etc. There are belts to transmit energy, seals to support radial or reciprocating parts, gaskets and O-rings to seal in oils and fuels, hoses to deliver liquid and gases and diaphragms to control them. Figure 1 shows one example of elastomers for gasoline engines reported by Akema and Yoshida. Rubbers are soft polymeric materials having generally 100 MPa of Young's modulus (shown in Figure 2) for the normally applied temperature range. They are widely used for the buffer position between high modulus materials such as metals, plastics, glasses, etc., in energy transmission, liquid delivery, and energy isolation positions. The materials are selected for their resistance to fuels, oils, and heat; as well as their cold flexibility and sealing ability. However, different materials are sometimes selected for the same device depending upon such factors as applied temperature, class of fuels and oils, and the engineering design of the car. The many problems confronting the automotive industry these days are shown in Table A-I. They are roughly classified into two areas: environmental and safety. Elastomers for automotive applications have been changing to solve many kinds of problems. Table A-II shows the trends of rubber materials being used for automotive parts. High performance rubbers, which have heat resistance, long life, low permeability, good abrasion resistance, and so on, are all being adopted.
This paper presents the mechanical behavior and the molecular arrangement of the carbon-black filled SBR under uni-and biaxial stretching. The stress of filled SBR, estimated from the stress-temperature experiment under uniaxial stretching, changed from the entropy component to the internal energy component with the concentration of carbon black. Under biaxial stretching the stress is composed of an internal energy contribution from a low load of black. The structural change of the rubber was observed by the X-ray diffraction and the electron microscope. The stretching of SBR produces the oriented, densely packed pseudocrystalline regions and thin molecular regions. Under biaxial stretching the rubber chains orient parallel to the film and the stream of the densely packed layers is observed.
ZUSAMMENFASSUNG:Das mechanische Verhalten und die molekulare Anordnung von ruDgefulltem SBR wurde unter uniaxialem und biaxialem Verstrecken untersucht. Mit zunehmendem Gehalt an RUB erhoht sich der Energieanteil gegenuber dem Entropieanteil der Spannung, wie aus Spannungs-Temperatur-Experimenten geschlossen wurde. Unter biaxialer Beanspruchung besteht schon bei geringem RuDanteil ein Energiebeitrag in der Spannung. Strukturelle Veranderungen des SBR wurden mittels Rontgen-Diffraktion und Elektronenmikroskopie untersucht. Die Verstreckung ruft orientierte, dichtgepackte, pseudokristalline Bereiche und verdunnte Bereiche hervor. Bei biaxialer Streckung orientieren sich die Ketten parallel zum Film, wobei dichtgepackte Schichten beobachtet wurden.
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