Affiliation(s)
1. TECOS, Slovenian Tool and Die Development Centre, Celje 3000, Slovenia
2. OMAPLAST, Grosuplje 1230, Slovenia
3. ECOPULP Finland Oy, Koria 45610, Finland
4. AITIIP Centro Tecnológico, Polígono Empresarium, Zaragoza 50720, Spain
ABSTRACT
This study investigates the mechanical, thermal and morphological
properties of rHDPE (Recycled High Density Polyethylene) and a mixture of rPE
HD/LD (High and Low Density Polyethylene), both reinforced with rNP (Reclaimed
Newsprint Paper) fibres. To enhance the composite properties, the addition of
highly grafted maleic anhydride polyethylene wax, as CA (Coupling Agent), and
semi crystalline copolymer of propylene and ethylene, as IM (Impact Modifier), was
included into the material formulation by a twin-screw extruder. Mechanical and
morphological properties were studied on tensile test specimens, prepared by
injection moulding, by tensile testing machine and SEM (Scanning Electron Microscope), respectively.
Thermal properties, i.e. melting and crystallization behaviour, were
investigated by DSC (Differential Scanning Calorimetry). Mechanical analysis
showed that the addition of rNP in both composites increased the young modulus
and significantly decreased the elongation at break. The DSC results revealed
that the addition of the rNP in the rHDPE matrix led to a substantial decrease
of crystallinity, which consequently affects the tensile strength of the composite (17 MPa) in contrast to the neat
rHDPE (25 MPa). On the contrary, fibre addition in rPE HD/LD matrix had no specific impact
on the crystallinity index, but did contribute to the increased tensile
strength (26 MPa) when compared with neat rPE HD/LD (16 MPa). SEM
photomicrographs of the impact fracture surfaces demonstrated a solid adhesion
bond between the natural fibres and the rPE HD/LD matrix. Reclaimed newsprint
fibres can thus be considered as a perspective alternative to the inorganic
fillers in the rPE HD/LD composite.
KEYWORDS
Recycled high and low density polyethylene,
natural fibres, mechanical properties, DSC, recycling.
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References