Recycling of Fiber Reinforced Thermosets
Cured thermosets consist of crosslinked polymers. Therefore they cannot be processed repeatedly and were considered to be not recyclable. In this paper it is shown, how the structure of the FRP is broken down by mechanical or thermal processes so that particle and fibre fractions are reclaimed for the reinforcement of plastics.
The mechanical properties of standard-SMC/BMC change only slightly if the filler volume is partly substituted by particle regrind. Fibre regrind improves the strength but does not provide the pro¬perties of virgin glass fibres. The rigid fibre regrind does not form a close fibre network and con¬tains only 25 vol.-% of glass fibres. The reinforcement 01 the fibre regrind in SMC can be attribu¬ted to structural changes in the prepreg. The particles of the regrind are bonded physically and mechanically but not chemically to the UP-resin. As the interphase between resin and filler is the mechanical weak point and dominates the failure mechanism under load, the weak interphase between regrind and resin causes no decrease in matrix strength. The maximum content of re¬grind is limited by the high viscosity, which can be reduced by additives. Separating the matrix of the FRP by pyrolysis yields glass fibres, which provide good reinforcement in spite of their thermal damages.
The stiffness of thermoplastics (PP, PA 6) can be improved considerably and the strength slightly by fibre regrind. Compounds with a CF-EP-regrind provide better properties than compounds with GF-EP and show electrical conductivity. The performance of shortfibre reinforced thermoplastics is not achieved even when the regrind is treated with a coupling agent. Reasons can be found in the reduced fibre length, the high volume ratio of the not reinforcing resin, the poor coupling and inhomogenious distribution 01 the fibre bundles. The EP-resin can be separated from the car¬bon fibres by thermal decomposition. Long fibres are then reclaimed improving the properties of the compound.Lesen Sie die deutsche Zusammenfassung auf Kunststoffe.de
DRP, Fibre Reinforced Composites, SMC, Fibers, Recycling
Institute / chair: Technische Fakultät der Universität Erlangen-Nürnberg
Technical consultant for expert services: Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK) / Kunststoffe.de, Prof. Dr.-Ing. Manfred Neitzel
Publication year: 1995
Provider: Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK) / Kunststoffe.de
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