Introduction and intention:
The reinforcement of elastomers by silica/silane systems has been of central focus in the rubber industry in the last decades. This domain has proven to be very relevant because of the advantages this silica technology, which applies silica/silane systems to improve wet traction properties, reduce heat build up, lowers the rolling resistance etc. has brought to the tire and its related industries. These and many more advantages of silica technology will go a long way to cut down the CO2 emissions by reducing fuel consumption of cars as a result of lowering the rolling resistance tires.
Though much research work has been performed over the last decades to study and improve the properties of silica/silane filled compounds, a full understanding of the silica/silane system especially the reinforcement mechanism is still to be achieved. A study of the reinforcing network structure generated by different silanes in the silica/silane system could help bring more insights into the reinforcement of this system since the reinforcing network structure is one of the key parameters influencing the physical, mechanical and dynamic properties of elastomers filled with silica/silane systems. The reaction between silane and silica a described in a high number of publications and can be controlled easily by the analyses on ethanol in most cases. But the reaction of sulfur in presence of different S-containing silane systems with the polymer generating polymer-polymer-crosslinks or polymer-silane-silica bonds is investigated relatively less. Application of methods like the thiol amine method to determine the crosslink structures are not working well, especially in the L-SBR systems. So overall there is a high interest to learn more about the crosslinking reaction in presence of silanes and about the influence of different silane systems on the network structure. Especially in the use of common analytical methods for network characterization a gap is existing.
This research work will be aimed at studying the reinforcing sulfur network structure in silica/silane systems. An understanding of this reinforcing structure is of utmost importance to understand and describe the observed macroscale properties of elastomers generated using different silica/silane system. The objectives are as follows:
Procedure and methods
In order to achieve these objectives, isoprene rubber, SBR and analytically accessible low molecular model substances as well as different silica fillers will be employed in this study. Si-(OCH2CH3)3-CH3, Si (OCH2CH3)3-(CH2)3-SH, Si-(OCH2CH3)3-(CH2)3-S-S-(CH2)3-Si-(OCH2CH3), and Si (OCH2CH3)3-(CH2)3-S-S-S-S-(CH2)3-Si-(OCH2CH3) are the silane coupling agents that will be investigated (others are possible, to be agreed). The vulcanization system, sulfur/accelerator concentration and ratio, and silica/silane concentrations are the parameters that will be varied.
As for the analytical techniques, 1H-nuclear magnetic resonance (t2 and delta-shifts), liquid chromatography – mass spectrometry (LC-MS), gas chromatography – mass spectrometry (GC-MS), magnetic spectroscopy (x-ray linear dichroism-XLD) and the thiol amine method, equilibrium swelling, TSSR and/or dynamic flocculation model) will be applied for the investigations. Especially the thiol amine method has to be validated or optimized to be used in silica/silane –SBR-systems, because normally the method is published for NR-systems without fillers.
The project should be organized as multi client project, sharing the costs between the participants. The work will be carried out by a PHD student of DIK with support by a technician under supervision of Prof. Dr. U. Giese.
Duration: 18 month
Costs: 120,000 EUR shared by the project partners.
Prof. Dr. Ulrich Giese
Telefon: +49 511 84201-10