Super-clean recycling

One crucial parameter for the evaluation of a super-clean recycling process producing a recyclate suitable for food contact is the contamination level of the input material. Due to the fact that diffusion is a reversible process, the higher diffusive polymer types should have higher input levels of post-consumer contaminants. The first step in the evaluation of PCR polymer should therefore be the determination of the input concentrations of post-consumer compounds in the polymer materials. Eor a review of concentration of post-consumer compounds in packaging materials intended for recycling see ref. 8. 

Challenge test A test of the effectiveness of a super-clean recycling process to remove chemical contamination from materials or articles. The test involves introduction of exaggerated levels of surrogates and includes as an end parameter the migration evaluation of these surrogates from a model food contact article. 

Super clean PET recycling, i.e., conventional PET recycling with an additional deep cleansing process, for example, solid state postcondensation. The resulting material can be expected to be suitable for direct food contact applications [12]. 

VDF polymerization technology based upon super critical or liquid carbon dioxide as polymerization media has been reported (57-62). This technology offers an advantage in the polymer isolation step where a clean dry polymer is produced simply by depressimzation. The residual monomeifs) and CO2 can be recycled back to the reactor. PVDF is not soluble in CO2 (58-60) and as a result, additional pol5uneric stabilizers are required to produce stable particles. Adequate CO2 density for pol5unerization requires pressure significantly higher (typically >100 bar) than a conventional emulsion polymerization. 

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