CORDIS provides links to public deliverables and publications of HORIZON projects.
Links to deliverables and publications from FP7 projects, as well as links to some specific result types such as dataset and software, are dynamically retrieved from OpenAIRE .
Exploitable results
In the Mini Derucom project quality routines like raw material acceptance tests and similar were investigated in the mixing rooms of the processing partners. It was found that most of the raw materials are specified sufficiently with a number of quality parameters. The only quality parameter, which varies significantly with respect to its specification limits, is the pellet hardness of carbon black. To the contrary, the carbon black fines content is low in the condition of delivery but can change dramatically within the mixing room in dependence of the conveying system and its settings. Some quality parameters of EPDM polymers were found not specified exactly though influencing the process significantly. The degree of long chain branching and the content of processing aids can be named here. These parameters have been investigated with respect to end article quality in case of different applications within the Mini Derucom project. Furthermore, the exchange of raw materials at constant raw material specification in special application like covered rolls, rubber sleeves and closed cell insulation materials was found to some extend impossible. This means that raw material specifications cant be standardised. The specification limits of raw materials must be fixed between the rubber processor and raw material suppliers with respect to end article needs. However, only a number of selected raw materials have been focused in the project, which have been appropriated for investigations in the project. Furthermore, it was decided to focus those raw materials, which are used in recipes in large amounts. On the one hand these parameters are supposed to have influence on the process respectively the quality but on the other hand the information gained in the project is surely limited. The main results of all studies in the Mini Derucom project can be summarised as follows:
It is almost impossible to find general rules in terms of quality prediction of end article properties. The connection between end article properties and influencing factors depends strongly on the end article itself, its production process and the type of raw materials used. It can be stated that there are recipes showing significant variations of compound properties in case of provoked variations though the end article quality stays constant. The opposite effect was observed, too: The compound properties exhibit no variations at all though the end article quality varies in dependence of the parameter variations applied. If a direct correlation between e.g. raw material quality parameter variations, compound properties and end article quality could have been discovered, only highly sophisticated testing methods like RELMA, the RPA or the TOPO method were found to have predictive capabilities. On the other hand the success of end article prediction cant be addressed to a single testing method. It can be stated that the type of testing method depends on the recipe composition respectively the type of application, too. The reason must be seen in the fact that raw materials have a "statistical" nature, which are handled through processes that are also "statistical". It follows that whatever the complexity of a test on the material is at a given point of the process, the results of testing procedures have very limited predictive capabilities in a generalised way. On the other hand it was found that the mixer is a very sensitive machine to discover influences arising from raw materials. Assuming good sensor technology and data assembling units are installed on the mixer, internal mixers can be used as a sensor indicating quality problems of raw materials. However, this only works if the mixing process will be not controlled.
It was concluded to set up a quality assurance concept for the mixing room covering different fields of quality impacts: At first, knowledge about the influence of raw material quality parameter variations has to be assembled in a data base working like an expert knowledge system. Such expert knowledge includes more general information, which is independent of the application, as well as strictly application related factory floor information. The Mini Derucom project clearly demonstrated corresponding guidelines to gain expert knowledge on basis of a so-called "Mixing Room Study" and a "Parameter Analysis Study". Every rubber processor must perform these studies by himself due to the strong relation of quality influencing factors to the recipe respectively certain end article properties. Some general information like the influence of the carbon black pellet hardness, the fines content or the EPDM quality parameter long chain branching has been clarified already in the Mini Derucom project, which then can be used in expert knowledge systems. Furthermore, such systems should also contain information about the mixing procedure like the optimum fill factor, which is often disregarded. Another field of quality impacts in the mixing room covers ideal equipment, which is recommended used. Herewith, homogenous com-pound quality within one batch and from batch to batch can be obtained with respect to process efficiency. If the type of application will be un-sensitive against impacts of any kind, such equipment would at least have the advantage of improved process efficiency. The type of advisable equipment or special features, which are in some cases known to improve compound quality and mixing efficiency for long, can be listed as follows: a) mixing room control: systems to handle and to control raw material data, weighing procedures, the mixing process and testing results like MixCont or simpler ones; b) mixer: latest rotor geometry, hydraulic activated ram, variable rotor speed, automated oil injection; c) conveying system: dense phase conveying system including a rubber in-liner if low structured blacks have to be conveyed; d) minimum testing equipment: RELMA, RPA, QS extruder. The basic idea is to serve sufficient compound quality in terms of dispersive and distributive mixing behaviour and to test only these properties in the mixing room. Rubber processors would only have to investigate correlations between the results of these methods and end article quality.
The advanced testing methods RELMA and RPA have been improved within the project, too. RELMA was developed to be a tool for raw material characterisation as well. Furthermore, the whole unit was improved in technical respect significantly. The flexible optical cable was exchanged towards a fixed optic. Herewith the signals of sulphur could be amplified. The burned spot was homogenized and handling of the unit was improved by the application of new standard software. At the same time new sensor technology (spectrometer) and new gratings were bought, which have further amplified the sulphur signals about factor 40. Thus RELMA was developed a significant step forward to be a standard analysis tool in the mixing room. Similar developments were done with the RPA. Standard protocols were set up and processability indicators were introduced, able to distinguish the processing behaviour of rubber compounds more properly than e.g. the Mooney device. Furthermore, software was developed, able to qualify and quantify the non-linearity of compounds and it was found that the distortion of the response of a sinusoidal signal depends of the type of gum and the amount of fillers in the recipe. Last but not least the temperature conditions within the RPA cavity have been found far away from isothermal conditions.
The most important realisation of the Mini Derucom project must be seen in the fact that the recipe composition, the raw materials quality parameters and the processing equipment strongly depend on each other and to end article quality. There are no general rules available, which are able to describe quality of rubber articles. It makes not much sense to optimise only one step of the quality influencing fields: recipe composition, raw material quality, weighing accuracy and raw material handling, mixing quality, testing strategy. It only makes sense to develop a strategy, which can be then applied in a certain mixing room and to certain recipe respectively end article needs.
Searching for OpenAIRE data...
There was an error trying to search data from OpenAIRE
No results available