Improving the mechanical recycling and reuse of mixed plastics and polymer composites

This is a post-print version of the chapter.In this chapter we will explore the possibilities and viability of commercially recycling and reusing of composites and mixed polymer based waste that is difficult and expensive to separate into individual generic polymers for subsequent recycling. The chapter will also attempt to cover legislations that hinder and drive this technology and give sources of information for further examples of polymer recycling in action

Wood polymer composites and their contribution to cascading utilisation

Due to a shortage of resources and a growing competition of land use, sustainable and efficient resource utilisation becomes increasingly important. The application and multiple, cascading utilisation of renewable resources is aimed at to ensure an allocation and future availability of resources. Wood polymer composites (WPCs) are a group of innovative materials consisting of mainly renewable resources. By means of summarizing recent research, it is shown how WPC can potentially contribute to an enhanced cascading utilisation. For the production of WPC, waste materials and by-products from wood and agricultural industry, e.g. offcuts, sawdust, residues from board manufacturing, pulping sludge, can serve as a raw material. Furthermore, the cited literature presents the use of recycled polymers and biopolymers as a potential alternative for the polymer component of WPC. By using biodegradable polymers, a fully biodegradable composite can be formed. In addition to using recycled materials and potentially being biodegradable, it is pointed out that WPC furthermore offers the possibility of being recycled itself, therefore being considered as a “green composite”. Although the influence of contaminated waste streams and mixed filler and polymer types on the properties of WPC made with such recyclates is yet not fully understood and no collection systems exist for post-consumer WPC, in-house recycling on the production sites is identified as a promising option as it reduces production costs and enhances resource efficiency and cascading utilisation. On the basis of cited life cycle assessments, the eco friendliness of WPC is assessed resulting in the conclusion that WPC cannot compete with solid wood with respect to environmental impact but is an environmentally friendly alternative to neat plastics in several applications

Poly(oxime-ester) Vitrimers with Catalyst-Free Bond Exchange.

Vitrimers are network polymers that undergo associative bond exchange reactions in the condensed phase above a threshold temperature, dictated by the exchangeable bonds comprising the vitrimer. For vitrimers, chemistries reliant on poorly nucleophilic bond exchange partners (e.g., hydroxy-functionalized alkanes) or poorly electrophilic exchangeable bonds, catalysts are required to lower the threshold temperature, which is undesirable in that catalyst leaching or deactivation diminishes its influence over time and may compromise reuse. Here we show how to access catalyst-free bond exchange reactions in catalyst-dependent polyester vitrimers by obviating conventional ester bonds in favor of oxime-esters. Poly(oxime-ester) (POE) vitrimers are synthesized using thiol-ene click chemistry, affording high stretchability and malleability. POE vitrimers are readily recycled with little degradation of their initial mechanical properties, suggesting exciting opportunities for sustainable plastics

(Bio)degradable polymeric materials for sustainable future—Part 3: Degradation studies of the PHA/wood flour-based composites and preliminary tests of antimicrobial activity

© 2020 The Authors. Published by MDPI. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.3390/ma13092200The need for a cost reduction of the materials derived from (bio)degradable polymers forces research development into the formation of biocomposites with cheaper fillers. As additives can be made using the post-consumer wood, generated during wood products processing, re-use of recycled waste materials in the production of biocomposites can be an environmentally friendly way to minimalize and/or utilize the amount of the solid waste. Also, bioactive materials, which possess small amounts of antimicrobial additives belong to a very attractive packaging industry solution. This paper presents a study into the biodegradation, under laboratory composting conditions, of the composites that consist of poly[(R)-3-hydroxybutyrate-co-4-hydroxybutyrate)] and wood flour as a polymer matrix and natural filler, respectively. Thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy were used to evaluate the degradation progress of the obtained composites with different amounts of wood flour. The degradation products were characterized by multistage electrospray ionization mass spectrometry. Also, preliminary tests of the antimicrobial activity of selected materials with the addition of nisin were performed. The obtained results suggest that the different amount of filler has a significant influence on the degradation profile.Published onlin

Advanced Reprocessing – The Potential for Continuous Chromatographic Separations

This concept paper, discusses the challenges and opportunities for an extractive chromatographic process for the separation of fission products and minor actinides from uranium and plutonium isotopes in irradiated nuclear fuel. The paper highlights the constraints of the PUREX process, a process that is universally accepted for reprocessing of spent nuclear fuel now and for GEN IV reactor systems. It also identifies the challenges that a new separation process would have to overcome to dislodge its acceptance by both the operators and regulators. Although the concept of using a chromatography technique for this separation is challenging, recent developments of continuous chromatography such as simulated moving bed (SMB) and/or continuous annular chromatography (CAC) provides a degree of encouragement. Equally the development of new stationary phases in particular inorganic exchangers, many of which have not been examined for this application enhances confidence that an alternative to the PUREX process is possible

An Integration Of Taguchi Method And Grey Relational Analysis In Optimizing Injection Moulding Processing Parameter Of Recycled Plastic

In this research, the effect of blending compositions of recycled polyamide 66 with 33% glass fiber filled (PA66-GF) is investigated and evaluated based on the dimensional stability, mechanical and rheological properties. Dalam kajian ini, kesan pengadunan komposisi poliamida 66 yang mengandungi 33% gentian kaca yang dikitar semula, disiasat dan dinilai berdasarkan kestabilan dimensi, sifat mekanik dan reologi

Review of standards for biodegradable plastic bags.

The Single Use Carrier Bags Charges (England) Order 2015 requires retailers to charge at least 5p for each single use carrier bag, except where exempted. Under section 18 of that order, the Secretary of State must— (a) complete a review of industry standards for the biodegradability of lightweight plastic material; and (b) lay a copy of a report before Parliament setting out the conclusions of the review, in particular— (i) whether it appears to the Secretary of State that there exists an industry standard appropriate for the purposes of an exclusion from the obligations specified in Part 2 on grounds of biodegradability; and (ii) if so, how that exclusion would be implemented. That review has now been completed. It found that there are a number of standards for plastic bag biodegradability. We will need to conduct further work before any of these could be used to exempt certain types of carrier bags on grounds of biodegradability. By the end of May 2016 retailers are required to report the number of bags that have been supplied, and the uses to which the proceeds of the charge have been put, after reasonable costs are deducted. The Government will use that opportunity to consider the early impacts of the charge. The Government will continue to consider the technical specification for a genuinely biodegradable bag, and will at that point further report on how an exemption for such a biodegradable bag can be implemented

Migration of contaminants from food packages to its content – Brazilian scenario and regulation

Consumers demand pleasant taste and odor in the final food product. Changes in these characteristics may be due to food deterioration or migration of substances from the packaging into food. The production of plastics for food containers involves catalysts which may contain toxic elements. In Brazil, there are limits of migratory substances and procedures for determining its rate. We aim to emphasize the food risks of migration of toxic substances from plastic packaging into its contents, and the Brazilian regulations regarding this issue. PET (polyethylene terephthalate) as raw matter for food packaging, is a concern in Brazil. The research methods currently adopted in Brazil are efficient for As, Cd, Co, Cr, and Sb determination. During PET synthesis and recycling, secondary reactions may form acetaldehyde, diethylene glycol and toxic oligomers. Monitoring by government mechanisms is essential to enforce safe food packaging. However, migration over the product shelf life remains an issue