Chitosan/Silver Nanoparticle/Graphene Oxide Nanocomposites with Multi-Drug Release, Antimicrobial, and Photothermal Conversion Functions

In this work, we designed and fabricated a multifunctional nanocomposite system that consists of chitosan, raspberry-like silver nanoparticles, and graphene oxide. The room temperature atmospheric pressure microplasma (RT-APM) process provides a rapid, facile, and environmentally-friendly method for introducing silver nanoparticles into the composite system. Our composite can achieve a pH controlled single and/or dual drug release. Under pH 7.4 for methyl blue loaded on chitosan, the drug release profile features a burst release during the first 10 h, followed by a more stabilized release of 70–80% after 40–50 h. For fluorescein sodium loaded on graphene oxide, the drug release only reached 45% towards the end of 240 h. When the composite acted as a dual drug release system, the interaction of fluorescein sodium and methyl blue slowed down the methyl blue release rate. Under pH 4, both single and dual drug systems showed a much higher release rate. In addition, our composite system demonstrated strong antibacterial abilities against E. coli and S. aureus, as well as an excellent photothermal conversion effect under irradiation of near infrared lasers. The photothermal conversion efficiency can be controlled by the laser power. These unique functionalities of our nanocomposite point to its potential application in multiple areas, such as multimodal therapeutics in healthcare, water treatment, and anti-microbials, among others

Diverted from landfill: Manufacture and characterisation of composites from waste plastic packaging and waste glass fibres

This work explores the use of low-value packaging film-based waste mixed plastics (wMP) and waste glass fibres (wGF) to produce value-added composites. The study involves producing thermoplastic prepregs with wMP and wGF, manufacturing laminates via compression moulding, optimising wGF content, analysing the interface and assessing the performance of the laminates through mechanical testing. The results indicate that adding 18–26 vol% wGF to unreinforced wMP leads to significant improvements in tensile strength (over 300%), tensile modulus (500%), flexural modulus (over 700%), compressive strength (~350%), and compressive modulus (~700%) compared to unreinforced wMP. The significance of having 2D dispersion of short fibres with partial orientation compared to the more conventionally used 3D dispersion of short fibres is discussed. The research provides valuable scientific insights into the application of mixed waste materials in composites, aiding the creation of a more circular economy for plastic waste and leading to new composite products

Assessment of welded ignimbrite waste dust as a filler in rotomolded products: rheological and thermomechanical behavior of PP/ignimbrite composites

This work aims at demonstrating the potential benefits of using a mineral waste from quarries as a filler of polypropylene (PP) products obtained by rotational molding. A polypropylene matrix was dry blended with the ignimbrite dust (mainly composed of silica and alumina) in ratios up to 30% weight, obtaining well consolidated parts in all cases. However, it can be observed that, as expected, the parts with higher loadings result in a higher number of defects due to the air release hindering. The viscosity of the obtained blends was determined by oscillatory rheometry, finding that the incorporation of up to 30% of the mineral dust is not significantly affecting the viscous behavior of the material. Furthermore, the low particle size of the filler allows for a good distribution inside the PP matrix, obtaining a homogeneous material with good dispersion. The increased amount of ignimbrite results in improved storage modulus, meaning that the filler, even in dust format, is able to stiffen the matrix at high loadings (over 20%). However, increased ratios of filler also result in a lower adhesion between the filler and the matrix and reduced homogeneity of the blend.<br/