Abstract
High-density polyethylene (HDPE) was compounded with 3 wt% carbon nanotubes (CNTs). In order to simulate mechanical recycling, both the nanocomposite and neat HDPE were repeatedly extruded and subsequently analysed by tensile tests, Charpy impact strength, differential scanning calorimetry (DSC), oxidation induction time (OIT), Gel Performance Chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR) and TEM After 10 cycles of extrusion, thermal, mechanical, and rheological tests did not reveal any significant degradation. In order to better study the effect of the CNTs, a large number of cycles were simulated by processing the materials for up to 200 min. After 200 min of processing, the neat HDPE was significantly degraded whereas the nanocomposite was almost unaffected.
Highlights
High-density polyethylene (HPDE) is one of the most commonly used plastics, with a wide range of applications
The neat High-density polyethylene (HDPE) had a tensile strength of 27 Modulus (GPa) Tensile strength (MPa) and addition of carbon nanotubes (CNTs) to the polymer increased the tensile strength to 35 MPa, showing the reinforcing effect of the CNTs
Due to the stiff nature of the multiwall CNTs (MWCNTs), there was a significant reduction in the elongation when the CNTs were added to the polymer matrix
Summary
High-density polyethylene (HPDE) is one of the most commonly used plastics, with a wide range of applications. Mechanical recycling of HDPE has been studied in detail [1,2,3,4,5,6]. The number of times that HDPE can be recycled can vary depending on the processing conditions and the stabilization of the polymer, but, generally speaking, HDPE is relatively stable to degradation during repeated processing. Oblak et al processed HDPE through 100 extrusion cycles [4]. When the recycled polymer was characterised with nanoindentation, the hardness was almost unaffected after 10 extrusion cycles, and after 100 cycles the hardness was reduced to about 20% of its initial value. Repeated processing of HDPE has been studied for HPDE filled with natural fibres [7], wood flour [8], and glass fibres [9]
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