TAGS: Polymer Reinforcement
Rice University scientists have turned their attention to Joule heating of pyrolyzed plastic ash, a byproduct of plastic recycling processes. A strong jolt of energy flashes it into graphene.
Process to Enhance Circular Economy for Plastics
The technique by the lab of Rice chemist James Tour produces turbostratic graphene flakes that can be directly added to other substances like films of polyvinyl alcohol (PVA) that better resist water in packaging.
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This work enhances the circular economy for plastics,” Tour said. So much plastic waste is subject to pyrolysis in an effort to convert it back to monomers and oils. The monomers are used in repolymerization to make new plastics, and the oils are used in a variety of other applications. But there is always a remaining 10% to 20% ash that’s valueless and is generally sent to landfills.
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Now we can convert that ash into flash graphene that can be used to enhance the strength of other plastics and construction materials,” he said.
Pyrolysis involves heating a material to break it down without burning it. The products of pyrolyzed, recycled plastic include energy-rich gases, fuel oils, waxes, naphtha and virgin monomers from which new plastic can be produced. But the rest is discarded.
Experiments to Test the Flashed Ash
The researchers ran a pair of experiments to test the flashed ash, first mixing the resulting graphene with PVA, a biocompatible polymer being investigated for medical applications, fuel cell polymer electrolyte membranes and environmentally friendly packaging. It has been held back by the base material’s poor mechanical properties and vulnerability to water.
Adding as little as 0.1% of graphene increases the amount of strain the PVA composite can handle before failure by up to 30%, they reported. It also significantly improves the material’s resistance to water permeability.
In the second experiment, they observed significant increases in compressive strength by adding graphene from ash to Portland cement and concrete.
Source: Rice University