The presence of the smell of limonene in post-consumer plastic waste limits its use and quality

With the increase in the use of post-consumer plastics in the production of articles, the problem of identifying odors in the waste to be processed has also increased and, consequently, in the granules produced following recycling.

If until a few years ago the pungent and persistent odor in products made with post-consumer polymers was relatively tolerated, as they were intended for objects with limited destinations today, the massive use of these polymers in substitution of virgin raw material or post industrial waste, raises the problem of the smell of the finished product.

As we have already described in several articles on the blog, on the difficulty of using post-consumer recycled plastic polymers, in the presence of annoying odors, we can deepen the subject by talking about how it is possible to control the plastic supply chain to understand both the presence and the intensity of the chemical compounds that give rise to unpleasant odors.

The analysis can be done both from the point of view of the customer who buys the post-consumer polymer to produce the objects he will sell, and from that of the recycler who will have to analyze which batches of waste and in what quantities contain the substances that give rise to odors.

First of all we can say that in post-consumer plastic waste there are more than one chemical substance that gives rise to a series of odors, but that some are more pungent and annoying than others.

In particular, limonene is widely present and is difficult to eliminate, despite the plastic waste being duly treated with correct washing systems and adequate recycling procedures.

In fact, during the reception phase of the waste packages, which have come into contact during their waste life with many other products, as well as food products, it is important to have the ability to test the incoming flows to understand the incidence of substances that will create odor at the end of the recycling process, in order to be able to manage them with careful mixing of waste that has a low level of these odorous substances.

These compounds can be made on the basis of analytical data, not by sensation, so as to create a flow of raw material that can guarantee the user a certainty the percentage of odor contained in the granule.

As for companies that use post-consumer plastic polymer, it is essential to establish the acceptable odor target, with analytical calculations, in order to guarantee their end customers to buy a product, made with post-consumer recycled plastics, with an odor rate according to established parameters, not empirically through the use of testers who make their nose available.

This guarantee path, downstream and upstream of the process, can be carried out using a laboratory machine that uses ion mobility gas chromatography, which allows for analysis rapid (15 minutes) and automatic samples of waste or plastic granules or on finished products.

A simple insertion of the sample into the tubes and into the machine, allows a detailed analysis of the presence of chemical compounds in the sample.

Based on the graphic picture that the machine returns, the presence and intensity of the odorous components can be identified with certainty, taking the necessary actions to modify or accept or reject the product.

Automatic translation. We apologize for any inaccuracies. Original article in Italian.