Effects of HDPE Plastic Waste Aggregate on the Properties of Concrete

Polymer waste volumes have surged in recent years as a result of growing industrialization and fast improvements in living standards. In Malaysia, the majority of polymer waste is discarded rather than recycled. This circumstance results in major issues such as waste of natural resources and pollution of the environment. Polymer products, such as synthetic fibres, plastics, and rubber, are petrochemical compounds that disintegrate slowly in nature. Even after a long amount of time, plastic materials are not easily biodegradable. In reality, a wide range of waste materials can be used as a cement matrix inert. For the manufacture of the polymer concrete, trash bag plastics were employed as polymer wastes HDPE in this study (PC). The purpose of this research is to investigate the characteristics and characterisation of polymer HDPE as a coarse aggregate replacement in concrete. Temperatures of 160°C, 170°C, 180°C, 190°C, and 200°C were used in the heating procedure. By volumetric approach, five compositions of coarse aggregate with varied crushed stone: HDPE waste ratios of 0:100, 15:85, 30:70, 45:55, and 60:40 were utilised. The use of polymerwaste as coarse aggregate in traditional concrete was examined. With fresh and hardened concrete tests, the effects of polymer wastes on the workability and strength of the concrete were investigated. After 28 days, the compressive strength of the PCwas determined to be suitable for nonstructural use. The findings of the cost research revealed that the PC is more cost effective than traditional concrete. Keywords: Polymer Wastes HDPE; Coarse Aggregate; Compressive Strength; Properties

Waste-to-Energy: Production of Fuel Gases from Plastic Wastes

A new mechanochemical method was developed to convert polymer wastes, polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC), to fuel gases (H2, CH4, and CO) under ball-milling with KMnO4 at room temperature. By using various solid-state characterizations (XPS, SEM, EDS, FTIR, and NMR), and density functional theory calculations, it was found that the activation followed the hydrogen atom transfer (HAT) mechanism. Two metal oxidant molecules were found to abstract two separate hydrogen atoms from the α–CH and β–CH units of substrates, [–βCH2–αCH(R)–]n, where R = H in PE, R = γCH3 in PP, and R = Cl in PVC, resulting in a di-radical, [–βCH•–αC•(R)–]. Subsequently, the two unpaired electrons of the di-radical were recombined into an alkene intermediate, [–βCH =αC(R)–], which underwent further oxidation to produce H2, CH4, and CO gases.

Retreatment of Polymer Wastes by Disintegrator Milling

Global introduction of waste utilization techniques to the polymer market is currently not fully developed but has enormous potential. Before reintegration of used material into a new product, it normally requires grinding, that is shredding, crushing, or milling. In traditional grinders, the generated stresses in the material to be ground are equal to or less than the strength of the material. If by traditional methods, the stresses generated are compressive + shift, so by milling based on collision are tension + shift. Due to the high stress-material strength ratio at collision, it is possible to crush not only brittle materials but also ductile materials. This process allows easily combining the grinding of composite materials with their separation into individual constituents. In the current study, the mechanical recycling of the following groups of polymer materials was studied: pure brittle and soft polymers (PMMA, HDPE and IER), blends of plastics (ABS+PMMA, PC + ABS), reinforced plastics (PMMA+GFP); elastomers (rubber and tyres), and printed circuit boards (PCB).

Polymer Degradation: Category, Mechanism and Development Prospect

With the increasing demand for polymers, white pollution has become a serious concern all around the world. The admirable degradation methods of them are desirable for overcoming this problem. In the past several decades, numerous researches on polymer degradation have been reported. This review commits to different degradation strategies of polymers and four main degradation protocols firstly, including photodegradation, oxidative degradation, catalytic degradation, and biodegradation, are demonstrated in detail. Secondly, some specific samples are discussed for each kind of degradation. Finally, the outlook and future of polymer degradation are proposed. In particular, the comprehensive comparison of different degradation methods is covered to provide the best choice for dealing with different polymers wastes. These will be beneficial to the development of processing plastic and conversion of polymer wastes.

Simple pyrolysis of polystyrene into valuable chemicals

Overuse of polymer products has led to severe environmental problems, which are threatening survival of creatures on earth. It is urgent to tackle enormous polymer wastes with proper cycling methods. Pyrolysis of polymers into high-value chemicals and fuels is displaying great potential to address the white pollution issue. In this study, we focus on chemical recycling of polystyrene, an important polymer in our everyday life, into valuable chemicals through simple pyrolysis strategy under nitrogen protection. It is found that yield of liquid product from polystyrene pyrolysis achieves as high as 76.24%, and there exists single component in the liquid product, which has been identified as styrene through hydrogen nuclear magnetic resonance spectra. Moreover, we propose monomer dissociation mechanism to explain the pyrolysis process of polystyrene based on the structure of polystyrene and experimental results.

Development of Sorbent Materials based on Polymer Waste and their Compounds with Nanomaterials for Oil Spill Remediation

Aims: The purpose of this work was to obtain a hydrophobic sorbent material with potential applications in oil spill remediation. Background: The accidents due to oil spills cause long-term ecological damage, especially in the aquatic environment. The cleaning of oil spills can be carried out by many methods and techniques, being absorbents the most attractive due to the possibility of recovery and complete elimination of the hydrocarbons in situ from the water surface. In recent years, interest in polymeric materials for oil spill remediation has increased due to its low cost, high stability, and recyclability. Objective: The objective of this work was the development of sorbent materials based on polymer wastes, such as Polyethylene Terephthalate (PET), obtained from recycled bottles, and recycled Polyurethane (PU), for its application in the recovery of oil spills. Methods: Sorbent materials were prepared from polymer wastes, using salt molds for the formation of porous materials with a composition of PU of 5, 10 and 15%, which were subsequently hydrophobized using carbon nanotubes or silica nanoparticles by dip-coating technique. Results and Discussion: The obtained hydrophobic sorbent materials were characterized by Scanning Electron Microscopy (SEM) and Infrared Spectroscopy (FTIR). The resulting absorbent has shown capacity to separate oil from water; the best result was obtained by the sponge of PET-PU (10% PU) hydrophobized with a suspension with low multi-wall carbon nanotubes (MWCNTs) concentration, obtaining an absorption capacity of 2.01 g/g. Conclusion: Besides the standard sorption capacity, these cheap sorbent materials had interesting properties like low density, high hydrophobicity and buoyancy, which could be applied in other applications related to solving oil spills.