Thermoset polymers are not biodegradable, a fact that has blighted the plastic molding industry for some time. But now plastic injection manufacturers may be able to reap the benefits of a recent advance in recycling that will render plastic molding-created thermoset polymers recyclable. While this discovery, pioneered by IBM Almaden Research Center, may not extend to all types of thermoset plastic, the innovative recycling process should be able to tackle the lion’s share of thermoset plastics.
From Polymer to Monomer
Heat forges thermoset polymers through plastic molding processes that leaves the finished product irreversibly cross-linked. This is why it’s thus far been an impossible feat to break down the finished product. One may assume that if plastic molding uses heat to create thermoset polymers, the finished plastic could be likewise broken down into its basic compounds through heat. But this is not a situation in which fire can be used to combat fire. The depth of the cross-linking in plastics that have been thermoset through plastic injection molding results in them being impervious to dis-assembly through heat. The researchers at IBM Almaden instead created a type of thermoset polymer that could be broken down through the application of a powerful acid. The plastic was then able to be re-molded, unlike any thermoset plastics that preceded it. Plastic molding may have rendered the product into a polymer, but the novel application of this acid returned the product into a monomer state that could be recreated in a new form.
The Diels-Alder Reaction
By the researching scientists’ own admission using the acid application process, referred to as the Diels-Alder reaction, is very simple. The Diels-Alder reaction has actually been in play since the late 1920s, but it wasn’t until IBM Almaden’s tests that the procedure was considered in response to thermoset plastics. While the process may have been around for decades, the tests results and methods still need to be properly introduced to plastic molding manufacturers before it is incorporated into their own processes. The simplicity of the Diels-Alder process means that many manufacturers working in plastic molding can then quickly begin implementing the process without significant sacrifices in money and time. In addition, the Diels-Alder reaction is not restrained by a patent though resulting polymers may be subject.
Testing to Meet the Standards of Plastic Molding Companies
A degradation of quality in the return from polymer to monomer has not been ruled out. Before plastic molding companies begin to fully embrace the Diels-Alder system, more tests will be conducted to measure the quality loss inherent in the process. The plastics will be subjected to several lives to provide these statistics. A lot of the plastic molding process relies heavily on physical attributes of the finished product that could be adversely affected by the return from polymer to monomer. Before the plastic molding industry adopts the Diels-Alder process it will need to be proven to not compromise the integrity of the finished product.
Thermoset polymers that litter landfills will still be taking up space hundreds of years from now so advances made with the Diels-Alder reaction are no small feat. While manufacturers may still be a few tests away from mainstream use of this recycling process, plastic molding companies stand to benefit from a product made more valuable through recyclability.