The present invention relates to plasticized polyolefin compositions comprising a polyolefin and a non-functionalized hydrocarbon plasticizer.

Plasticized polyolefin compositions

A growing accumulation of plastic wastes has become a severe environmental and social issue. It is urgent to develop innovative approaches for the disposal of plastic wastes. In recent years, reports on biodegradation of synthetic plastics by microorganisms or enzymes have sprung up, and these offer a possibility to develop biological treatment technology for plastic wastes. In this review, we have comprehensively summarized the microorganisms and enzymes that are able to degrade a variety of generally used synthetic plastics, such as polyethylene (PE), polystyrene (PS), polypropylene (PP), polyvinyl chloride (PVC), polyurethane (PUR), and polyethylene terephthalate (PET). In addition, we have highlighted the microbial metabolic pathways for plastic depolymerization products and the current attempts toward utilization of such products as feedstocks for microbial production of chemicals with high value. Taken together, these findings will contribute to building a conception of bio-upcycling plastic wastes by connecting the biodegradation of plastic wastes to the biosynthesis of valuable chemicals in microorganisms. Last, but not least, we have discussed the challenges toward microbial degradation and valorization of plastic wastes.

/pdf/microbial-degradation-and-valorization-of-plastic-wastes-55isz32czl.pdf

Microbial Degradation and Valorization of Plastic Wastes.

Plastics pollution is causing an environmental crisis, prompting the development of new approaches for recycling, and upcycling. Here, we review challenges and opportunities in chemical and biological catalysis for plastics deconstruction, recycling, and upcycling. We stress the need for rigorous characterization and use of widely available substrates, such that catalyst performance can be compared across studies. Where appropriate, we draw parallels between catalysis on biomass and plastics, as both substrates are low-value, solid, recalcitrant polymers. Innovations in catalyst design and reaction engineering are needed to overcome kinetic and thermodynamic limitations of plastics deconstruction. Either chemical and biological catalysts will need to act interfacially, where catalysts function at a solid surface, or polymers will need to be solubilized or processed to smaller intermediates to facilitate improved catalyst–substrate interaction. Overall, developing catalyst-driven technologies for plastics deconstruction and upcycling is critical to incentivize improved plastics reclamation and reduce the severe global burden of plastic waste. Plastics are invaluable materials for modern society, although they result in the generation of large amounts of litter at the end of their life cycle. This Review explores the challenges and opportunities associated with the catalytic transformation of waste plastics, looking at both chemical and biological approaches to transforming such spent materials into a resource.

Chemical and biological catalysis for plastics recycling and upcycling

Plastics pollution represents a global environmental crisis. In response, microbes are evolving the capacity to utilize synthetic polymers as carbon and energy sources. Recently, Ideonella sakaiensis was reported to secrete a two-enzyme system to deconstruct polyethylene terephthalate (PET) to its constituent monomers. Specifically, the I. sakaiensis PETase depolymerizes PET, liberating soluble products, including mono(2-hydroxyethyl) terephthalate (MHET), which is cleaved to terephthalic acid and ethylene glycol by MHETase. Here, we report a 1.6 A resolution MHETase structure, illustrating that the MHETase core domain is similar to PETase, capped by a lid domain. Simulations of the catalytic itinerary predict that MHETase follows the canonical two-step serine hydrolase mechanism. Bioinformatics analysis suggests that MHETase evolved from ferulic acid esterases, and two homologous enzymes are shown to exhibit MHET turnover. Analysis of the two homologous enzymes and the MHETase S131G mutant demonstrates the importance of this residue for accommodation of MHET in the active site. We also demonstrate that the MHETase lid is crucial for hydrolysis of MHET and, furthermore, that MHETase does not turnover mono(2-hydroxyethyl)-furanoate or mono(2-hydroxyethyl)-isophthalate. A highly synergistic relationship between PETase and MHETase was observed for the conversion of amorphous PET film to monomers across all nonzero MHETase concentrations tested. Finally, we compare the performance of MHETase:PETase chimeric proteins of varying linker lengths, which all exhibit improved PET and MHET turnover relative to the free enzymes. Together, these results offer insights into the two-enzyme PET depolymerization system and will inform future efforts in the biological deconstruction and upcycling of mixed plastics.

https://www.pnas.org/content/pnas/117/41/25476.full.pdf

Characterization and engineering of a two-enzyme system for plastics depolymerization.

Plastic biodegradation: Frontline microbes and their enzymes

Towards bio-upcycling of polyethylene terephthalate

Enzymatic recycling of thermoplastic polyurethanes: Synergistic effect of an esterase and an amidase and recovery of building blocks.

An isolated active-clamp flyback power supply with a new resonant operation mode is designed and experimentally tested. A full soft-switching design based on dead-time optimization new approach is implemented. Each topology phase is detailed. An experimental board is presented for high ambient temperature (200 °C) operation. The power supply is dedicated to provide the driver power of wide bandgap power components in a phase-leg configuration. The constraint for galvanic isolation is high and guides the design of the transformer. The power-supply capabilities are 15 V input voltage, 6 V output voltage, 2 W output power, 75% peak efficiency, 11 cm2 footprint, and nominal operation at 200 °C ambient temperature.

High-Temperature GaN Active-Clamp Flyback Converter With Resonant Operation Mode

Synthesis and characterization of polyurethane foams derived of fully renewable polyester polyols from sorbitol

The present invention relates to a device for supporting and attaching panels to a roof comprising an added sealing covering on the surface thereof. Said device includes brackets for tiltedly supporting and bearing the panels, comprising a bottom bearing portion and at least one top portion for supporting the panels, said brackets having a triangular structure and consisting of a hollow body. Said device is characterised in that the bottom portion (4) of the brackets (3) is provided, on the underside thereof, with at least one added plate (5) secured to the console (3), wherein the plate(s) (5) consist of a material or contain a material that is compatible with and/or similar to the layer or the surface coating of the roof covering (2), and are bonded to said layer or said covering by an adhesive bond, and in that the top portion (4') provides bearing surfaces for the edges of the panels or profile members for mounting such panels.

Rémi Perrin

Papers

Towards bio-upcycling of polyethylene terephthalate

Enzymatic recycling of thermoplastic polyurethanes: Synergistic effect of an esterase and an amidase and recovery of building blocks.

High-Temperature GaN Active-Clamp Flyback Converter With Resonant Operation Mode

Synthesis and characterization of polyurethane foams derived of fully renewable polyester polyols from sorbitol

Device for supporting and attaching panels or the like, and roof system comprising such a device