Open Loop Recycling of Recycled Polypropylene for Motorcycle Saddle Application

Piyachat Wattanachai(1*), Benjawan Buasathain(2), Christian Antonio(3), Susan Roces(4)

(1) Department of Chemical Engineering, Faculty of Engineering, Burapha University, Sean Sook, Muang, Chonburi 20131, Thailand
(2) Department of Chemical Engineering, Faculty of Engineering, Burapha University, Sean Sook, Muang, Chonburi 20131, Thailand
(3) University of Queensland, Brisbane, QLD 4068, Australia
(4) Department of Chemical Engineering, De La Salle University, Manila 0922, Philippines
(*) Corresponding Author


This research investigated the possibility of using polymer blends of virgin and
recycled polypropylene (PP) for a motorcycle saddle application. Three different
recycled PPs obtained from different sources contained carbon black (CB). Specimens
were prepared by injection molding for mechanical property testing and color
characterization whereas scraps from runners were used for thermal property testing. It
was found that tensile and flexural properties of recycled PPs were better than those of
virgin PP due to the fact that recycled PPs contained CB which is a reinforcing material.
These properties were improved as the amount of recycled PP added increased. Since
recycled PPs are strong materials, they are hence brittle resulting in lowering impact
strength and percent elongation. The recycled PP sources and compatibility between
virgin and recycled PPs strongly influence the blends' properties. The melt flow index of
the blends increased as the amount of the recycled PP increased because of the short
polymer chains of recycled PP resulting from earlier processing. Blending virgin PP with
recycled PP not only improves its properties, but also reduces raw material costs in the
range of 5-13%. The advantage of open loop recycling is a wider recycled plastic


Polypropylene, recycled plastics, motorcycle parts, polymer blends, open loop recycling

Full Text:



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