High-density polyethylene (HDPE) is a commonly recycled plastic, notably from plastic drinking bottles. Recycled applications of HDPE are many and various including new packaging and textile fibres. But it is especially valued in automotive applications including fuel tanks, wiring, cables, pipes and fittings - due to its high tensile strength and excellent resistance to chemicals and hydrolysis.
However, HDPE recyclate is often contaminated with another similar plastic called polypropylene (PP), a common reason is that caps and pour spouts of HDPE bottles are made from PP. The problem with this, is that the presence of PP in recycled HDPE resin can adversely affect end-product performance causing brittleness and susceptibility to stress-cracking. So it is therefore crucial to find and eliminate PP for onward use in manufacturing automotive components.
In 2018, Ford announced the reuse of 1.2 billion recycled bottles. This accounted for 250 recycled plastic bottles in each of its manufactured vehicles for the year. So In order to maintain high quality, it is imperative that processors monitor and control the amount of PP contained in recycled resin. For this purpose, a reliable tool is Fourier Transform Infrared Spectroscopy (FT-IR), and, to that end, the PerkinElmer Spectrum Two™ FT-IR is the easy-to-use, accurate system for measuring the amount of PP in recycled HDPE resin.
This Application Report presents the methodology for employing the PerkinElmer Spectrum Two for this analysis.