Showing papers by "Leila L. Y. Visconte published in 2019"

Life Cycle Assessment of Polyethylene Terephthalate Packaging: An Overview

Abstract: Life cycle assessment (LCA) is a common technique to evaluate the environmental impact of poly(ethylene terephthalate) (PET) packaging. A review is needed to gain a clear view of the accumulated knowledge, scientific trends and what remains to be done. The main purpose of this paper is to present an overview of LCA of PET, mainly for packaging. LCA studies of PET consist largely of two segments: final destination of post-consumer PET, comparing recycling with other options (incineration, landfilling); and alternative materials, comparing PET with other polymers or materials such as glass and aluminum cans. In the first case, the scenarios most often compared have been landfill disposal and mechanical recycling. There has also been considerable research on the use of post-consumer PET for energy conversion and chemical recycling. In the second case, the main polymer compared with PET is poly(lactic acid), whose mechanical properties make it unsuitable for carbonated beverage bottles. Numerous articles have focused only on energy consumption or global warming potential. Few studies have discussed mechanical recycling technologies in LCA and there is a lack of data on the processes used in developing countries. This review highlights the need to conduct LCA studies of PET, since many aspects are still not fully understood.

End-of-Life Tire Destination from a Life Cycle Assessment Perspective

Abstract: Tires are complex materials manufactured from vulcanized rubber and various other reinforcing materials. One billion end-of-life tires (ELTs) are discarded annually, drawing attention from society. Options for their disposal include reuse, retreading, regeneration, co-processing, pyrolysis, and recycling; however, the ideal alternative has yet to be established. Life cycle assessment (LCA) has been used to quantify their impact and support the decision-making process, in order to determine the most beneficial alternative from an environmental standpoint. Scientific studies on LCA have been carried out on different continents, mainly Europe, Asia, and America. The aim of this chapter was to review studies on the life cycle assessment of end-of-life tire disposal. The main treatment and final destination options were reviewed as well as the most important limitations and aspects of the technologies studied. The most common form of disposal is recycling, with mechanical recycling for use in synthetic grass exhibiting the best environmental performance according to scientific research. Energy recovery also shows good performance, largely due to the emissions prevented through energy conversion. Co-processed and retreaded tires are regularly used for comparison but typically display poor environmental performance in relation to the first two alternatives.

The Use of Cashew Nut Shell Liquid (CNSL) in PP/HIPS Blends: Morphological, Thermal, Mechanical and Rheological Properties

Abstract: Polypropylene (PP) and high impact polystyrene (HIPS) are two polymers that are frequently found in disposable waste. Both of these polymers are restricted from being separated in several ways. An easier way to reuse them in new applications, without the need for separation, would require them to be less immiscible. In this work, cashew nut shell liquid (CNSL), a sub-product of the cashew agroindustry, was added as a third component to PP-HIPS mixtures and its effect as a compatibilizing agent was investigated. Morphological results showed that CNSL acted as an emulsifier by promoting reduction in the domains of the dispersive phase, HIPS, thus stabilizing the blends morphology. Differential scanning calorimetry (DSC) analysis suggests that CNSL is preferably incorporated in the HIPS phase. Its plasticizing effect leads to more flexible materials, but no significant effect could be detected on impact resistance or elongation at break.

Evaluation of rheological behavior, anaerobic and thermal degradation, and lifetime prediction of polylactide/poly(butylene adipate-co-terephthalate)/powdered nitrile rubber blends

Abstract: The present study aimed to investigate the effect of powdered nitrile rubber (NBR) content on the morphology, rheological behavior, anaerobic and thermal degradation, and life expectancy of blends based on polylactide (PLA) and poly(butylene adipate-co-terephthalate) (PBAT). The blends were prepared by extrusion and compression molding using a commercial PLA/PBAT (70:30 wt%) blend and powdered NBR coated with calcium carbonate (93:7 wt%). Photomicrographs from scanning electron microscopy revealed that the NBR particles, stained with osmium tetroxide, were preferentially located in the PLA matrix. Additionally, NBR contributed to reducing the size of PBAT domains. The rheological behavior of PLA/PBAT/NBR blends was dependent on rubber content, indicating that NBR plays an important role in blend flowability. Furthermore, a decline was observed in the activation energy needed to degrade 5% of the PLA contained in the blend, reducing the lifespan of NBR-based blends. This behavior was attributed to the thermal conductivity of the calcium carbonate present in the NBR. Finally, anaerobic degradation was not inhibited in the PLA/PBAT/NBR blend containing 20 wt% of rubber, although its biochemical methane potential was lower than that of PLA/PBAT/NBR.