In the manufacture of damping elements, the specific requirements in terms of the dynamic behavior of the end-product have always been the most important criterion. Less attention was paid in the past to the resistance of the end-product to the effects of increased temperatures, e.g. with engine mountings in an increasingly aggressive thermo-oxidative environment under the bonnet, and long-term rubber/metal bonding. The expectations that dampers now have to fulfill in terms of performance and service life are now high in all areas.
The production of an effective and durable damping element requires the design of suitable damper geometries and a carefully thought out compound formulation. The most used polymers in damper compounds are natural rubber (NR), chloroprene rubber (CR) and acrylic rubber (AEM).
Dynamic behavior is determined primarily by vulcanization method and quality. For the manufacture of sulphur-cured vulcanizates based on NR which are resistant to aging and dynamic fatigue, excellent sulphur dispersion is of the utmost importance. With Rhenogran® S-80, these requirements can be fulfilled even with problematic soft compounds.
The requirement for NR vulcanizates with good thermal stability, reversion resistance and extremely low heat build-up under dynamic stress can be fulfilled by using dithiophosphates. We supply these vulcanization chemicals and offer for this particular application Rhenocure® SDT/S or Rhenocure® ZBOP/S. Durable bonding of vulcanizates to metal surfaces is a major objective in the manufacture of damping elements. It is achieved by using predispersed bonding agents such as Rhenogran® Resorcin®-80 and Rhenogran® HEXA-80.
In order to guarantee the long-term efficacy of damping elements under thermo-oxidative conditions, suitable antioxidants must be used. Ever increasing temperatures in engine mounting applications (especially when NR is used) make this task difficult. Antioxidants such as Rhenofit® DDA and Rhenofit® OCD are particularly suitable for the effective prevention of crack formation caused by oxygen under conditions of dynamic stress.
For CR compounds, Rhein Chemie provides ETU free systems. This task is carried on by Rhenogran® MTT-80. Additionally for CR mixes, Rhein Chemie offers the antioxidant Rhenofit® OCD and the processing aid Aflux® 42 that acts as an excellent dispersing agent for fillers and rubber chemicals and increases the plasticity of uncured compounds and improves the flow properties.
For curing of AEM, Rhein Chemie has developed engineered curing systems and processing aids, e.g. Rhenogran® XLA-60, Rhenogran® HPCA-50, Rhenogran® HMDC-70/AEMD, Rhenogran® ZDDT-50/AEMD and Aflux® 18.