Restabilization – 30 years of research for quality improvement of recycled plastics review

Pfaendner, Rudolf

doi:10.1016/j.polymdegradstab.2022.110082

Cited by 27 publications

(20 citation statements)

References 133 publications

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“…H 4′ at δ H 4.17 ppm interacted with both C 3 and C 5 of the phenyl ring containing the hydroxyl group OH at δ H 12.65 pm. 1 H− 1 H COSY spectra provided the necessary information to identify all protons of the benzophenone, especially H 3 and H 5 at δ H 6.51 and 6.41 ppm. Other peaks of benzophenone could be easily attributed.…”

Section: Synthesis and Characterization Of Macromolecularmentioning

confidence: 99%

Low-Migration Macromolecular Benzophenones as UV Absorbers for Food Packaging Polymers

Nguyen

Lim

Jana

et al. 2023

ACS Appl. Polym. Mater.

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Extending the durability of polymer plastics and minimizing toxicity concerns to humans and the environment are among the essential goals toward sustainability. Continuing our efforts in this area, we report herein the design, optimized synthesis, and migration studies of macromolecular benzophenones (MBPs) using three important building blocks including poly(ethylene-co-acrylic acid), pentaerythritol, and tris(2,3-epoxypropyl)isocyanurate for sustainable food packaging applications. All MBPs are synthesized in gram scales, with the synthetic limitations being investigated. Interestingly, polymer-bound triphenyl phosphine is found to be an effective and recyclable Lewis-based catalyst for an epoxy ring opening reaction to prepare an MBP in only one step starting from 2,4-dihydroxybenzophenone. The migration profiles of MBPs are much improved in comparison with that of the small molecule BP-1 (Uvinul 3008) and on par with the Food and Drug Administration-approved macromolecular cyanoacrylate Uvinul 3030 (UVN). They also show an excellent ability to protect polystyrene from photodegradation and yellowing processes, suggesting that they may find a real-life application in the plastic industry.

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Section: Synthesis and Characterization Of Macromolecularmentioning

confidence: 99%

Low-Migration Macromolecular Benzophenones as UV Absorbers for Food Packaging Polymers

Nguyen

Lim

Jana

et al. 2023

ACS Appl. Polym. Mater.

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“…10 Quality challenges for mechanical recycling stem from its (i) direct dependence on input purity, (ii) uptake of contamination or incorporation of immiscible foreign polymeric materials, and (iii) damage to the polymer chains acquired during the first use phase and exacerbated by reprocessing during recycling. 11 At the current recycling rates, the global share of material entering the recycling stream again after having already been recycled once is still exceedingly low (globally, until 2015, according to Geyer et al no more than 1.2% of plastics have undergone >1 recycling loops 12 ). With increasing volumes and circularity ambition, however, multiple cycles will become more common, especially in systems with well-developed collection and extended producer responsibility schemes.…”

Section: Introductionmentioning

confidence: 99%

“…Together with higher quantities, 8 the quality 9 of recycling and use in high‐value applications 3 need to be addressed as key barriers 10 . Quality challenges for mechanical recycling stem from its (i) direct dependence on input purity, (ii) uptake of contamination or incorporation of immiscible foreign polymeric materials, and (iii) damage to the polymer chains acquired during the first use phase and exacerbated by reprocessing during recycling 11 . At the current recycling rates, the global share of material entering the recycling stream again after having already been recycled once is still exceedingly low (globally, until 2015, according to Geyer et al no more than 1.2% of plastics have undergone >1 recycling loops 12 ).…”

Section: Introductionmentioning

confidence: 99%

“…In these studies, the technically decisive aspect of polymer stabilization by additives 21 has not been an independent factor of the investigation. On the other hand, the foundational work on the importance of stabilization of polyolefins in recycling by Pfaendner et al has recently been reviewed 11a . Mihelčič et al investigated mechanical, thermal and rheological properties of recycled PP with and without stabilization, 22 and Bunjes et al additionally included additive analytics in their study of virgin and recycled PP 23 …”

Section: Introductionmentioning

confidence: 99%

“…Considering levels of 500–3000 ppm of stabilizers are commonly used to protect the polymers during the first loop, the levels of active species (e.g., phosphite) found in recyclates (Table 1) are often not sufficient anymore to protect the polymer from degradation during re‐processing and re‐use. In addition, impurities and contaminations have an impact on the stability of (and stabilization strategy for) recyclates 11b . For example, iron is found in various post‐consumer recyclates: Iron is a bi‐valent metal and it is known to catalyze radical chain reactions 14 .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Elucidating pathways of polypropylene chain cleavage and stabilization for multiple loop mechanical recycling

von Vacano,

Reich,

Huber

et al. 2023

Journal of Polymer Science

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Mechanical recycling is a decisive contribution for a sustainable circular economy of polypropylene (PP) but faces the challenge of processing‐induced and use‐phase accumulated molecular damage, exacerbated by multiple loop recycling. In this contribution, the molecular origin of degradation of PP under up to 30 repetitive reprocessing loops is analyzed together with the influence of stabilization, and processability data linked to changes of the entire molecular weight distribution. By comparison of experiments with simple Monte Carlo simulations, a coupled mechanism of random scission and shear‐induced cleavage can be inferred, while stabilizing additives effectively protect the material from progressing along this combined degradation pathway.

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UV Irradiation of Polyethylene Terephthalate and Polypropylene and Detection of Formed Microplastic Particles Down to 1 μm

Mikac,

Csáki,

Zentai

et al. 2023

ChemPlusChem

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We investigated the degradation of plastics upon UVC irradiation in aqueous solution and the formation of microplastic (MP) particles. We irradiated polypropylene (PP) and recycled and virgin polyethylene terephthalate (PET) with a UV lamp emitting at 254 nm. Irradiation was performed for 15 and 30 min, respectively, at an intensity of about 0.3 W cm‐2. The formation of MP was studied by Raman spectroscopy. The results showed that MP particles were formed after irradiation and that their number was significantly higher in the recycled PET than in the virgin material. The number of PP MP formed was lower compared to PET and was not significantly different after 15 and 30 min. In addition, ethanol was used as an alternative solvent to investigate how its chemical properties and interactions with UVC irradiation affect the degradation of PET and PP plastics. The use of ethanol and recycled PET resulted in a lower number of MP particles at both irradiation times. When ethanol was used after 30 min of irradiation, significantly more PP MP formed. The different chemical structures of PET and PP combined with the different solvent properties of water and ethanol contribute to the differences in their susceptibility to UVC degradation.

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Restabilization – 30 years of research for quality improvement of recycled plastics review

Cited by 27 publications

References 133 publications

Low-Migration Macromolecular Benzophenones as UV Absorbers for Food Packaging Polymers

Low-Migration Macromolecular Benzophenones as UV Absorbers for Food Packaging Polymers

Elucidating pathways of polypropylene chain cleavage and stabilization for multiple loop mechanical recycling

UV Irradiation of Polyethylene Terephthalate and Polypropylene and Detection of Formed Microplastic Particles Down to 1 μm

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