Search

Microplastics are emerging micropollutants in water threatening aquatic and land organisms. The microplastic–water system is complicated due to the multiple constituents in the water system and the minuscule size of the plastic waste. Although typical plastic-based materials are inert, the behavior of fragmented plastics is arbitrary and indefinite. When exposed to erratic water environments with the presence of organic and synthetic impurities, pH, temperature, and salt, microplastic surfaces may be potentially active and generate charges in water. These phenomena determine microplastics in water as a colloidal system. The classical Derjaguin Landau Verwey and Overbeek (DLVO) theory can be used to identify the microplastic surface behavior in water. The modification of microplastic surfaces eventually determines the overall interactions between microplastics and other constituents in water. Moreover, the geometry of microplastics and additives present in microcontaminants play a crucial role in their net interactions. Hence, multiple microplastic removal techniques, such as coagulation, filtration, and air flotation, can be developed to address the issue. In many cases, a combination of these methods may be needed to achieve the overall procedure in water treatment plants or generic water systems. Selection of an appropriate microplastic removal technique is crucial and should be based on the water environment and intended water use to ensure its safety.

The present study was aimed at synthesis of polymeric hydrogels for controlled boron (B) release, as B deficiency is a major factor that decreases crops yield. Thus, graphene oxide incorporated guar gum and poly (ethylene glycol) hydrogels were prepared using the Solution Casting method for boron release. 3-Glycidyloxypropyl trimethoxysilane (GLYMOL) was used as a cross-linker. Characterizations of hydrogels were carried out by Fourier Transform Infrared Spectroscopy (FTIR), Thermo-Gravimetric Analysis and Scanning Electron scope. The FTIR outcomes confirmed the existence of functional groups, bindings and development of hydrogel frameworks from incorporated components. The quantity of GLYMOL directly increased the thermal stability and water retention but decreased the swelling %. The maximum swelling for the hydrogel formulations was observed at pH 7. The addition of GLYMOL changed the diffusion from quasi-Fickcian to non-Fickcian diffusion. The maximum swelling quantities of 3822% and 3342% were exhibited by GPP (control) and GPP-8 in distilled water, respectively. Boron release was determined in distilled water and sandy soil by azomethine-H test using UV-Visible spectrophotometer while 85.11% and 73.65% boron was released from BGPP-16, respectively. In short, water retentive, water holding capacities, swelling performances, biodegradability and swelling/deswelling features would offer an ideal platform for boron release in sustained agricultural applications.

This study used water as the physical blowing agent as well as microwave heating (MH) and convection heating (CH) to simultaneously foam and cure natural rubber foam (NRF). Various processing methods and parameters, such as single heating and sequential heating using a mix of CH and MH; were investigated. The correlation between these processing methods as well as different water loadings was then evaluated and compared in terms of physical appearance, density, and morphology. The NRF samples produced using sequential MH and CH (SMC) heating exhibited better shape and structure than samples produced using single heating of either CH or MH only as well as sequential CH and MH (SCM) heating at all water loadings. NRF samples with water loadings of 1.5 and 2.0 phr had a density of less than 0.1 g/cm3. The potential heating mechanism of all the heating methods explored in this study was proposed and discussed to further understand the microwave heating process. The findings of this study proved that water could be utilized as a physical blowing agent in the production of NRF products with microwave-assisted foaming.

Self-healing rubbers have been widely developed by introducing reversible dynamic crosslinked networks into rubber so that it can repair mechanical damage automatically without requiring any manual intervention. The major successful self-healing methods in rubber and underlying mechanisms, such as the covalent adaptable network and supramolecular interaction, were reviewed. Although these methods have been established to develop self-healing rubber, the materials often exhibit relatively poor mechanical properties compared to traditional rubber. In addition, the unique properties of vitrimers as a new class of polymer network is described in the covalent adaptable network subsection. This review also focuses on the effect of filler reinforcement using fillers such as carbon base, silica, chitin and cellulose nanocrystals, as well as metallic and other types, which can participate in reversible crosslink reactions and enhance the mechanical properties. The review also includes an overview of the applications of self-healing rubber.

As most plastic materials disintegrate without being properly reused after they are discarded, this present study developed a novel thermoplastic elastomer (TPE) using recycled high-density polyethylene (rHDPE) and natural rubber (NR) with kenaf fibre as a sustainable filler. Apart from being used as filler, this present study aimed to examine the use of kenaf fibre as a natural anti-degradant as well. The results indicated that the tensile strength of the samples was found to have significantly decreased after 6 months of natural weathering and had decreased by a further 30% after 12 months due to the chain scission of the polymeric backbones and the degradation of the kenaf fibre. However, the composites that contained kenaf fibre significantly retained their properties post-natural weathering. In terms of tensile strength and elongation at the break, the addition of only 10 phr of kenaf increased the retention properties by 25% and 5%, respectively. This is noteworthy as kenaf fibre also contains a certain amount of natural anti-degradants. Therefore, as the kenaf fibre improves the weather resistance of composites, plastic manufacturers could use it as either a filler or a natural anti-degradant.

A massive demand for rubber-based goods, particularly gloves, was sparked by the emergence of the COVID-19 epidemic worldwide. This resulted in thousands of tons of gloves being scrapped due to the constant demand for the items, endangering our environment in a grave way. In this work, we aimed to focus on the utilization of waste nitrile gloves (r-NBR) as a component blended with natural rubber (NR). The life span and other related properties of the blend can be improved by proper control of the chemical recipe. This study assessed three types of crosslinking systems, namely sulfur (S), peroxide (DCP), and mixed sulfur/peroxide (S/DCP) systems. The results indicate that choosing S/DCP strongly affected the tensile strength of the blend, especially at relatively high contents of r-NBR, improving the strength by 40–60% for cases with 25–35 phr of r-NBR. The improvement depended on the crosslink types induced in the blends. It is interesting to highlight that the thermal resistance of the blends was significantly improved by using the S/DCP system. This indicates that the life span of this blend can be prolonged by using a proper curing system. Overall, the S/DCP showed the best results, superior to those with S and DCP crosslinking systems.

An intrinsic self-healing natural rubber featuring reversible metal-thiolate ion networks was fabricated and the corresponding healing mechanism and mechanical properties were presented. The developed materials were able to repair themselves at room temperature upon damage without any external stimuli. Reversible metal-thiolate ion networks were proven to form within the rubber material. These networks dominated the cross-linking system and were identified by Differential Scanning Calorimetry (DSC) and Fourier-transform Infrared Spectroscopy (FTIR). Meanwhile, the quantitative amount of metal-thiolate ion networks and covalent crosslinks was determined by swelling testing. Scanning Electron Microscopy (SEM) results revealed that intermolecular diffusion had occurred at the fracture area of the self-healing samples. The results revealed that the mechanical properties could be 100% regenerated after the broken samples were brought into contact with each other. It was also found that self-healing increased by 60% of the material lifespan. This new material is expected to open up promising avenues for the manufacturing of sustainable rubber products.