Search results for "natural rubber"

Über die polymeranaloge bromierung von naturkautschuk und einige lösungseigensch aften des bromkautschuks. Über die molekularen konstanten von naturk…

1961

Naturkautschuk last sich in verdunnter Losung in Cyclohexan bromieren, wobei das Molekulargewicht entsprechend dem Bromgehalt zunimmt (polymeranaloge Umsetzung). Fur Bromkautschuk steigenden Bromgehalts wird Cyclohexan ein zunehmend schlechteres Losungsmittel, was sich in einer Abnahme des 2. osmotischen Virialkoeffizienten und einer Kontraktion des Molekulknauels zeigt. Dieses Ergebnis wird in quantitativer Ubereinstimmung durch Viskositats- und Lichtstreuungsmessungen erhalten. Cyclohexanlosungen von Bromkautschuk mit 43% Brom haben bei Zimmertemperatur einen Θ-Punkt. In diesem Zustand ist der Knauel 1,74mal groser als bei freier Drehbarkeit, in ziemlich guter Ubereinstimmung mit dem an a…

1978

For the three different cases (R=polybutadiene, polypropylene oxide and EPDM) the isothermal cloud point curves of the system styrene/polystyrene/rubber (S/PS/R) show that at 25°C a decomposition into two phases occurs already in the presence of a few percents of polystyrene and rubber. By separating the phases (centrifuge) and analysis of coexisting phases, tie lines and thus critical points could be fixed. Evaluation of the results was made on the basis of the Flory and Huggins theory by means of approximations given for such systems by Scott. The interaction parameters resulting for 25°C are well in agreement with literature data—as far as available. By means of the approximations mentio…

Softening of Silica Filled Styrene-Butadiene Rubber under Uniaxial Cyclic Loading

2016

Stress-strain behaviour of silica filled styrene-butadiene rubber showed strong hysteresis and cyclic softening, while these effects were almost negligible for the neat rubber. Significant Mullins effect occurs between the first and second loading cycles, whereupon samples reach their steady state after four repeated cycles. The degree of softening increases with volume content of silica characterizing the softening effect as a breakdown of the filler-formed microstructure defined by both, specific interactions in the filler associations and between the filler and rubber matrix. Contribution of different damage mechanisms to the total energy losses on different stages of extension was estim…

Volume Changes in Filled Rubber Under Uniaxial Cyclic Loading

2011

Styrene-butadiene rubber, neat and filled with different silica content was investigated under uniaxial cyclic loading under a constant crosshead speed, with increasing deformation amplitude in subsequent loading cycles. Rubber was investigated in order to evaluate the reversibility of structure rearrangements, occurring in rubber when subjected to cyclic loading. Volume uniformly increases with growing strain and shows hysteresis at unloading. After complete unloading, no residual strain changes are observed. These data are in good conformity with the data of density measurements, which were made on specimens before and after the tests. By correlating data, obtained from volume changes and…