Mechanical and chemical recycling of solid plastic waste

This review presents a comprehensive description of the current pathways for recycling of polymers, via both mechanical and chemical recycling. The principles of these recycling pathways are framed against current-day industrial reality, by discussing predominant industrial technologies, design strategies and recycling examples of specific waste streams. Starting with an overview on types of solid plastic waste (SPW) and their origins, the manuscript continues with a discussion on the different valorisation options for SPW. The section on mechanical recycling contains an overview of current sorting technologies, specific challenges for mechanical recycling such as thermo-mechanical or lifetime degradation and the immiscibility of polymer blends. It also includes some industrial examples such as polyethylene terephthalate (PET) recycling, and SPW from post-consumer packaging, end-of-life vehicles or electr(on)ic devices. A separate section is dedicated to the relationship between design and recycling, emphasizing the role of concepts such as Design from Recycling. The section on chemical recycling collects a state-of-the-art on techniques such as chemolysis, pyrolysis, fluid catalytic cracking, hydrogen techniques and gasification. Additionally, this review discusses the main challenges (and some potential remedies) to these recycling strategies and ground them in the relevant polymer science, thus providing an academic angle as well as an applied one.

Preparation and characterization of nitrile butadiene rubber-nanoclay composites with maleic acid anhydride as compatibilizer. Part I

Nitrile butadiene rubber (NBR)-nanoclay composites have been prepared. Maleic acid anhydride-treated organoclay (MOC) was synthesized and utilized as a compatibilizer. The prepared clay structures were analyzed by Fourier transform infrared (FTIR) spectroscopy. Furthermore, the FTIR investigation confirmed the incorporation of (MOC) in the NBR matrix, X-ray diffraction analysis indicated that an exfoliated structure was obtained, and scanning electron microscope images displayed the good interaction between the MOC and the rubber matrix. The influence of the MOC content (i.e. 1, 3, 5, 10, 20 phr) relative to the micrometer clay (i.e. 10, 20 phr) on the NBR compounds was analyzed through rheometric and swelling characteristics. The rheometric study demonstrated an increase in minimum and maximum torques, delayed scorch time and optimum cure time for the MOC (3 phr)-incorporated NBR compound compared to pure NBR. The cure rate index followed the same trend. In addition, these particular compounds showed decreased equilibrium swelling in toluene solvent, increased crosslinking density, a greater volume fraction and bound rubber content compared to the corresponding rubber filled with micrometer clay.