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  • Time-dependent, thermal and rheological properties of LDPE after exposure to simulated recycling
    Jin, Huiying ...
    Materials for plastic recycling come from two sources: process scrap and post-consumer waste. Large amounts of process scrap, i.e. polymers left over from the production of plastics, are available ... during extrusion and injection moulding. Process scrap is relatively simple and economical to recycle as there is regular and reliable supply, moreover materials are relatively uncontaminated. Nevertheless, in order to use recycled polymers their mechanical properties, durability, aesthetics and overall functionality must be preserved to the highest possible degree. Consequently, it is important to be able to predict the properties of recycled polymers. In this paper, low density polyethylene (LDPE) was exposed to forty (40) consecutive extrusion cycles to simulate the process of scrap mechanical recycling. Recycled samples for characterization were taken after the first ten extrusions and after that from every next tenth extrusion cycle. The evolution of thermal, rheological, as well as, time-dependent mechanical properties accompanying the gradual degradation of the recycled polymers were monitored and evaluated by means of DSC, rheological measurement (SAOS) and creep measurement. In addition, extrusion conditions such as torque and pressure were monitored. The results show that simulated recycling did not significantly change the measured extrusion parameters, thermal properties and time-dependent mechanical properties of LDPE. However, there was notable change in LDPE rheological properties after repeated extrusion. Viscosity and the viscoelastic moduli decreased after the first extrusion cycle, then starting on the second extrusion cycle rheological functions steadily increased. Investigated rheological properties of recycled materials suggest that gelation and thermal degradation of LDPE occur after repeated extrusion. The seresults should be considered if recycled LDPE is to be used in production of structurally more demanding goods.
    Vir: Conference proceedings (Str. 277-280)
    Vrsta gradiva - prispevek na konferenci
    Leto - 2011
    Jezik - angleški
    COBISS.SI-ID - 12008987

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