Chromatographic pattern in recycled high-impact polystyrene (HIPS) – Occurrence of low molecular weight compounds during the life cycle

Multifactorial evaluation of an ultra-fast process for electrospinning of recycled expanded polystyrene to manufacture high-efficiency membranes for nanoparticle air filtration

The increased production of polystyrene waste has led to the need to find efficient ways to dispose of it. One possibility is the use of solid waste to produce filter media by the electrospinning technique. The aim of this work was to develop an ultra-fast electrospinning process applied to recycled polystyrene, with statistical evaluation of the influence of polymeric solution parameters (polymer concentration and percentage of DL-limonene) and process variables (flow rate, voltage, and type of support) on nanoparticle collection efficiency, air permeability, and fiber diameter. An extensive characterization of the materials and evaluation of the morphology of the fibers was also carried out. It was found that recycled expanded polystyrene could be used in electrospinning to produce polymeric membranes. The optimized condition that resulted in the highest nanoparticle collection efficiency was a polymer concentration of 13.5%, percentage of DL-limonene of 50%, voltage of 25 kV, and flow rate of 1.2 mL/h, resulting in values of 99.97 ± 0.01%, 2.6 ± 0.5 × 10-13 m2, 0.19 Pa-1, and 708 ± 176 nm for the collection efficiency of nanoparticles in the range from 6.38 to 232.9 nm, permeability, quality factor, and mean fiber diameter, respectively. All the parameters were found to influence collection efficiency and fiber diameter. The use of DL-limonene, a natural solvent, provided benefits including increased collection efficiency and decreased fiber size. In addition, the electrostatic filtration mechanism was evaluated using the presence of a copper grid as a support for the nanofibers. The findings demonstrated that an electrospinning time of only 5 min was sufficient to obtain filters with high collection efficiencies and low pressure drops, opening perspectives for the application of polystyrene waste in the development of materials with excellent characteristics for application in the area of atmospheric pollution mitigation.

Safety of recycled plastics and textiles: Review on the detection, identification and safety assessment of contaminants

In 2019, 368 mln tonnes of plastics were produced worldwide. Likewise, the textiles and apparel industry, with an annual revenue of 1.3 trillion USD in 2016, is one of the largest fast-growing industries. Sustainable use of resources forces the development of new plastic and textile recycling methods and implementation of the circular economy (reduce, reuse and recycle) concept. However, circular use of plastics and textiles could lead to the accumulation of a variety of contaminants in the recycled product. This paper first reviewed the origin and nature of potential hazards that arise from recycling processes of plastics and textiles. Next, we reviewed current analytical methods and safety assessment frameworks that could be adapted to detect and identify these contaminants. Various contaminants can end up in recycled plastic. Phthalates are formed during waste collection while flame retardants and heavy metals are introduced during the recycling process. Contaminants linked to textile recycling include; detergents, resistant coatings, flame retardants, plastics coatings, antibacterial and anti-mould agents, pesticides, dyes, volatile organic compounds and nanomaterials. However, information is limited and further research is required. Various techniques are available that have detected various compounds, However, standards have to be developed in order to identify these compounds. Furthermore, the techniques mentioned in this review cover a wide range of organic chemicals, but studies covering potential inorganic contamination in recycled materials are still missing. Finally, approaches like TTC and CoMSAS for risk assessment should be used for recycled plastic and textile materials.

Investigation of polymer-based composites by laser desorption/ionization study of their photo-oxidative aging

RATIONALE

Polybutadiene (PB) is one of the most widely used polymers. Its aging occurs by reaction with oxygen under illumination and may modify its mechanical and/or aesthetic properties. To modify its properties, organic and/or inorganic compounds are generally added to PB. The aging of such composite materials is poorly known.

METHODS

PB and its mixtures with TiO₂ and/or the Orange 13 pigment are subjected to an accelerated photo-oxidative aging step for one week. The analysis of PB and its composites with regard to their composition and the aging time is carried out by 266 nm and/or 355 nm laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (LDI-FTICR-MS).

RESULTS

Both PB and its degradation products are detected by (+) LDI-FTICR-MS. The oxidation mechanism of PB is not significantly affected by the used organic or inorganic fillers, which results from the cleavage of the polymer chain and the formation of carbonyl compounds. The crosslinking of PB is significantly reduced by the two investigated fillers. Analysis in negative mode [(-) LDI-FTICR-MS] ensures the specific detection of the Orange 13 pigment.

CONCLUSIONS

LDI-FTICR-MS has demonstrated its ability to provide relevant information on the degradation of polymer-based composites. The main advantages of this approach are its ability to probe the surface, which is specifically affected by photo-oxidation aging processes, and to access the insoluble degradation compounds.

Influence of impurities on the performances of HIPS recycled from Waste Electric and Electronic Equipment (WEEE)

In order to produce a high quality recycled material from real deposits of electric and electronic equipment, the rate of impurities in different blended grades of reclaimed materials has to be reduced. Setting up industrial recycling procedures requires to deal with the main types of polymers presents in WEEE (Waste Electric and Electronic Equipment), particularly High Impact Polystyrene (HIPS) as well as other styrenic polymers such as Acrylonitrile-Butadiene-Styrene (ABS), Polystyrene (PS) but also polyolefin which are present into WEEE deposit as Polypropylene (PP). The production of a substantial quantity of recycled materials implies to improve and master the compatibility of different HIPS grades. The influence of polymeric impurities has to be studied since automatic sorting techniques are not able to remove completely these fractions. Investigation of the influence of minor ABS, PS and PP polymer fractions as impurities has been done on microstructure and mechanical properties of HIPS using environmental scanning electron microscopy (ESEM) in order to determine the maximum tolerated rate for each of them into HIPS after sorting and recycling operations.

NS, Riegel IC. Estudo da recuperação das propriedades de poliestireno de alto impacto (HIPS) através da incorporação de borracha termoplástica tipo estireno-butadieno-estireno (SBS)

A tenacificação de termoplásticos vítreos através da adição de partículas de borracha na matriz polimérica é um processo amplamente estudado. Neste trabalho foi avaliada a recuperação das propriedades de poliestireno de alto impacto (HIPS) reciclado através da incorporação de copolímeros estireno-butadieno-estireno (SBS) de estrutura linear e radial. As blendas foram processadas em uma extrusora dupla rosca. Os copolímeros foram adicionados em teores de 5, 10 e 15% em massa. As propriedades avaliadas foram o índice de fluidez, a morfologia e o comportamento frente a ensaios de tração, flexão e resistência ao impacto das blendas formuladas. Em todos os casos, o SBS radial foi mais eficiente na recuperação das propriedades do poliestireno de alto impacto que o SBS linear quando comparadas às propriedades do HIPS reciclado.