Innovative technologies for hard-to-recycle plastics

Not all plastics are created equal when it comes to recycling. While PET bottles and HDPE containers have well-established recovery chains, a large share of everyday packaging falls into a category often described as hard-to-recycle plastics: multilayer flexible films, black or dark-pigmented trays, foamed polystyrene, and composite materials that combine plastic with paper, foil or adhesives. For decades, much of this material was simply landfilled or incinerated because conventional sorting lines could not separate it economically. That picture is now changing, thanks to a wave of innovation in sensing, sorting and material science.

Understanding the challenge of hard-to-recycle plastics

The core challenge with hard-to-recycle plastics is heterogeneity. A multilayer pouch for snacks or coffee, for example, may combine polyethylene, polypropylene, an aluminium barrier layer and printed inks – all bonded so tightly that mechanical separation is impractical. Black plastics present a different problem: traditional near-infrared (NIR) sorting sensors rely on light reflecting back from the material, and carbon-black pigments absorb that light almost completely, making the polymer essentially "invisible" to older sorting equipment. As a result, black trays and containers were historically routed to rejects regardless of the polymer they were made from. Composite and foamed materials add yet another layer of complexity: expanded polystyrene is extremely light and bulky, complicating transport and handling, while laminated cartons require specialised pulping processes to separate the fibre from the plastic and foil layers.

How recycling companies manage difficult-to-recycle plastic?

The most significant advances have come from sensor technology. Newer detection systems combine near-infrared with visible-spectrum cameras, laser-induced fluorescence and even hyperspectral imaging, allowing sorting equipment to "see" beyond the limitations of carbon-black pigments and identify the underlying polymer of dark plastics with high accuracy. Artificial intelligence and deep learning models trained on large image datasets can now recognise packaging shapes, printed labels and material textures, helping to separate multilayer films by their dominant polymer even when the material itself is opaque to traditional sensors.

On the chemistry side, advances in chemical and enzymatic recycling are opening routes for materials that mechanical recycling cannot handle – breaking complex polymers down into their basic building blocks so they can be remanufactured into virgin-equivalent plastic. While these processes are still scaling up, they depend heavily on having a clean, well-characterised feedstock. At PICVISA, our ECOFLAKE and ECOPACK systems are designed precisely for this challenge: combining advanced optical sensors, AI-based recognition and high-speed ejection to separate complex plastic streams – including dark and multilayer materials – into purer fractions that downstream recyclers and chemical recycling plants can actually use.

FAQs: understanding why plastics are difficult to recycle

Why can't black plastic be sorted by ordinary machines? Carbon-black pigments absorb near-infrared light almost completely, so older sensors cannot identify the polymer underneath. Newer multi-sensor and AI-based systems are overcoming this limitation.

Are multilayer films ever recyclable? In principle yes, through chemical recycling that breaks the material down to its base polymers, but this depends on receiving a consistent, well-sorted feedstock – which is where optical sorting plays its part.

What happens to plastics that cannot currently be recycled? They are typically sent to energy recovery or landfill, but as sorting and processing technology improves, more of these fractions are finding genuine recycling routes rather than ending their journey there.

Explore ECOFLAKE plastic sorting