Tuesday, June 16th, 2015
Moving Beyond What’s Easy: Compatibilizer Report from SPI Aims to Improve Quality of Recycled Plastics, Enhance Chemical Skill Set throughout Recycling Value Chain
The plastics recycling industry presently faces an environment of lower bale quality and lower yields. It also faces increasing demand for post-consumer recycled material, right at a time when providing that material is especially complicated and costly. Rather than waiting around for bale quality to increase on its own (or for MRFs to place a greater priority on better sorting), recyclers need to become more sophisticated in order to adjust their operations to suit a new normal.
The problem of processing contaminated materials like bales of mixed multi-layer consumer plastic packaging is a chemical one, and so it makes sense to attempt to address it with a chemical solution. But chemistry, at least at the moment, isn’t a strong suit for most recyclers. “SPI is supported by polymer, additive, and machinery makers,” said Sal Monte, president of Kenrich Petrochemicals, a member of SPI’s Recycling Committee. “There are hundreds of different kinds of polymers/processes and their subset applications that all have different functions and market applications, but the recyclers who collect that plastic until recently have not had to operate at that level.”
“Most of the guys who deal with recycle are not chemists,” he added. “If they want to make useful parts that give recycled plastic a second life on a first-tier level, recyclers are going to have to become more knowledgeable about polymer material science.”
Education and innovation are key to raising the bar for the entire recycling value chain, and a new report, titled “Compatibilizers: Creating New Opportunity for Mixed Plastics,” is the SPI Recycling Committee’s latest attempt to challenge recyclers to move beyond what’s easy and push the entire recycling value chain forward in a way that yields new applications and new value for mixed post-consumer recycled plastics.
Broadly speaking, compatibilizers are additives that get incompatible polymers to “talk” to one another. They’ve historically been used successfully in both the prime resin industry and in the post-industrial plastics recycling arena to increase the value of bales comprised of select mixed polymers, but their use in the post-consumer world has been limited. That’s what the Recycling Committee’s report aims to change. It introduces readers and recyclers to the opportunities these additives present to their business, and to the economic imperative these companies have to find new solutions in a world where the process of recycling plastic materials is only getting more and more complicated.
“Recent findings suggest HDPE recyclers are suffering a 20-percent yield loss, while their PET recycling counterparts are experiencing upwards of 40-percent yield loss,” the report says. “This rate of material loss can quickly change the economics of an operation from black to red. If that yield loss could be put to use as another valuable feed stream, it can dramatically change the economics of an operation, as well as further divert valuable plastics from the landfill.” Compatibilizers are one option recyclers can consider in their efforts enhance their profits while meeting their sustainability goals.
They can also enable the right recyclers with the right expertise to find new markets for their materials by allowing them to impart more desirable qualities to the recycled resin they produce. Incompatible polymers that are recycled can’t be used practically since they delaminate during melt processing such as injection molding to make a PCR containing plastic product. Virgin polymers are also chain scissored during melt processing, giving the resultant post-consumer recycled resin lesser mechanical properties when compared to virgin resin. This limits these materials’ usage in all kinds of applications requiring performance specification polymers.
In essence, compatibilizers enable resins that would not otherwise neatly blend into a useful melt of plastic materials to mix in such a way that the recycled resins acquire greater performance qualities than if the compatibilizer hadn’t been included. They have the potential to give streams of recycled plastic the qualities they require to be more useful, if not as useful as their virgin forefathers, and therefore much more valuable. “The use of compatibilizers is being explored increasingly in the recycling industry as a way to create value in mixed feed streams that cannot be further segregated by resin type, either due to technical challenges related to collecting, cleaning and sorting, or economic infeasibility,” the report observes.
There’s a sort of “if you can’t beat ‘em, join ‘em” simplicity to using compatibilizers to enhance the value of recycled materials—if you can’t fix bale quality, find a way to make bale quality matter less. But post-consumer recycling isn’t getting simpler; it’s getting more and more complex. To succeed in this environment, the recycling industry has to become more, not less, sophisticated. The Recycling Committee’s report is geared toward challenging recyclers to take their first step in that direction.