There is an approximately 3% of fresh water available globally for utilization, while the rest of the water is not available for usage, leaving billions of people with less water. Less water availability means that the majority of water consists of pollutants either in ground water or drinking water, which in turn may have a negative impact on the environment and people. Various methods such as plasma technology, flocculation, neutralization, and disinfection have been utilized for wastewater treatment. The wastewater treatment methods have been found to be selective in terms of the removal of other pollutants, as a result, the majority of them are unable to remove pollutants such as antibiotics at a trace level. In order to ensure that there is a complete removal of pollutants from water, there is a need for the development of alternative wastewater treatment methods. The use of solar light by photocatalysis is an alternative method for the degradation of toxic pollutants. Different photocatalysts such as zinc oxide (ZnO), titanium dioxide (TiO₂), and silver (Ag) have been used in the process of photocatalysis. However, the above photocatalysts were found to have drawbacks such as agglomeration at higher contents and health problems during transportation. To solve the above problem, the nanoparticles were immobilized in various matrices such as polymers and ceramics, with polymers being preferred because of low cost, chemical inertness, and high durability. The current review discusses various methods for the preparation of ZnO and its synergy with other nanoparticles incorporated in various polymer matrices. Because it is known that the preparation method(s) affects the morphology, the morphology and the photocatalytic activity of various ZnO/polymer composites and hybrid systems of ZnO/other nanoparticles/polymer composites are discussed in depth.

There is a sizeable amount of sawdust produced from wood industries such as timber and furniture. In the past, sawdust has been utilized as a fuel source and in the manufacturing of furniture. Based on the limited use of sawdust, there is plenty of sawdust accessible from the industries. Sawdust is the material of choice due to its cost effectiveness, environmental friendliness, and biodegradability. However, if sawdust is not appropriately disposed or utilized better, it may have negative impact on the aquatic life and organic products. Hence, this review paper discusses the best possible methods or proper routes for the utilization of sawdust to benefit the environment, society, and the economy at large. Sawdust possesses superior capabilities as a reinforcing filler in various polymer matrices for advanced applications. This paper provides an in-depth discussion on sawdust hybrid composites in comparison to other natural fibres hybrid composites. The applications of various sawdust hybrid polymer composites for specific systems are also mentioned. Furthermore, the morphology and preparation of the sawdust/polymer composites and/or sawdust hybrid polymers composites are also discussed since it is well known that the properties of the natural fibre composites are affected by the preparation method and the resultant morphology. Based on the above, the current paper also plays a critical role in providing more information about waste to value added products.

Poly(butylene succinate) (PBS) is a biodegradable polymer; however, a prolonged soil degradation rate of PBS limits its wide range of applications. Here, the impact of incorporating chitin in mechanical and thermal properties and soil degradation characteristics of PBS/hydroxyapatite (HAP) composites is investigated. Chitin is one of the most abundant natural polymers extensively used for various applications and has a fast soil degradation characteristic. Therefore, ternary PBS composites are melt‐processed in a twin‐screw extruder with a fixed amount of HAP (1.5 wt%) and two different loadings of chitin (1.5 and 3 wt%). Morphological characterization using transmission electron microscopy shows a homogeneous distribution of both fillers in a PBS composite containing 1.5 wt% chitin. In contrast, an optical microscopy study of the same composite at the melt state shows defibrillation and breakage of the chitin fibers during the extrusion. Incorporation of chitin decreases the elongation at break of the PBS/HAP composite, which is likely a consequence of chitin fiber morphology. However, the soil degradation characteristics and melt strength of PBS/HAP composites are improved in the presence of chitin fibers. In summary, chitin is shown to have the potential as an additive to obtain environmentally benign PBS composites for a wide range of applications.

The current study investigates a comparison of expandable graphite (EG) and montmorillonite clay (MMT) on the properties of polybutylene succinate (PBS)/maize stalk fiber (MSF) bio-composite. Maize stalk and fillers (EG and MMT) were incorporated into the PBS at 10 and 3 wt%, respectively. The scanning electron microscope (SEM) images showed a fibre pull-out from the PBS matrix, while the incorporation of 3 wt% of MMT improved the adhesion between the maize stalk and PBS matrix. In this study, the received MMT was already modified with octadecylamine and Aminopropyltriethoxysilane which improved the interaction between the fiber and PBS matrix. There seems to be a poor interaction between the MSF and EG, which influenced the properties between fiber and PBS negatively when compared with PBS/MSF/MMT hybrid composite. The flame resistance, and storage modulus of hybrid composites were improved due to better dispersion of MMT. The silane treated MMT based hybrid composite showed better flame retardancy (pHRR of 682.5 kW/m ² ) than the EG based hybrid composite system (pHRR of 697.6 kW/m ² ). The T _10% and T _50% of the PBS/MSF/MMT composite showed superior thermal stability than that of the PBS/MSF/EG composite. However, the T _10% and T _50% temperature values for PBS/MSF composite were revealed as 311.1°C and 363.9°C, respectively. Incorporation of MMT and EG to PBS/MSF enhanced the T _50% values of the composite to 372.2°C and 366.7°C, respectively.

The study investigated the effect of paraffin wax, expanded graphite, and their dispersion on the properties of the blend of polypropylene (PP) and ethylene vinyl acetate (EVA). The idea is to reduce interfacial tension in blends of PP and EVA while enhancing the properties of blends in the process. The chosen optimum contents of the paraffin wax and EG in the 80/20 PP/EVA blend were 10 and 6 wt.%, respectively. The morphological features show that the expanded graphite (EG) particles had high affinity for each other. Moreover, EG filler particles are localized inside the minor EVA phase and some at the interface. Rheological properties revealed that the flow of the binary composites increased when 10 wt.% wax is added suggesting that wax enhanced the processability of the composites. The Cole-Cole plots deviated from the semi-circular arc suggesting heterogeneity in the blend and PP/EVA/Wax/EG composite. The addition of paraffin wax and EVA delayed crystallization of PP, while earlier crystallization of PP was promoted by the presence of EG. Generally, all samples caught fire after 10 s, started dripping and are thus given a V-2 rating according to the Underwriters Laboratories test standard 94 results (UL-94).