Shear-induced change of exfoliation and orientation in polypropylene/montmorillonite nanocomposites

Ultrasound Sensors for Process Monitoring in Injection Moulding

Injection moulding is an extremely important industrial process, being one of the most commonly-used plastic formation techniques. However, the industry faces many current challenges associated with demands for greater product customisation, higher precision and, most urgently, a shift towards more sustainable materials and processing. Accurate real-time sensing of the material and part properties during processing is key to achieving rapid process optimisation and set-up, reducing down-times, and reducing waste material and energy in the production of defective products. While most commercial processes rely on point measurements of pressure and temperature, ultrasound transducers represent a non-invasive and non-destructive source of rich information on the mould, the cavity and the polymer melt, and its morphology, which affect critical quality parameters such as shrinkage and warpage. In this paper the relationship between polymer properties and the propagation of ultrasonic waves is described and the application of ultrasound measurements in injection moulding is evaluated. The principles and operation of both conventional and high temperature ultrasound transducers (HTUTs) are reviewed together with their impact on improving the efficiency of the injection moulding process. The benefits and challenges associated with the recent development of sol-gel methods for HTUT fabrication are described together with a synopsis of further research and development needed to ensure a greater industrial uptake of ultrasonic sensing in injection moulding.

Effects of Plasticizers and Clays on the Physical, Chemical, Mechanical, Thermal, and Morphological Properties of Potato Starch-Based Nanocomposite Films

Biodegradable polymeric films have great potential as alternatives to synthetic polymeric films to reduce environmental pollution. Plasticizing agents and nanofillers can improve the mechanical properties of polymer-based composites, resulting in materials with better flexibility and extensibility. Starch, a natural polymer, can be produced at low cost and on a large scale from abundant and inexpensive agricultural resources like potatoes. The aim of the present work was to fabricate mechanically strong and thermally stable potato starch films reinforced with different types of plasticizers and nanoclays at different concentrations. Different types of plasticizers such as water, glycerin, ethylene glycol, sorbitol, and formamide and three types of clays such as montmorillonite, hectorite, and kaolinite at various concentrations were used to prepare potato starch-based nanocomposite films. The films were prepared using a very simple solution casting process. The mechanical properties and thermal stabilities of nanocomposite films significantly improved using montmorillonite, hectorite, and kaolinite clays. The water uptake percentage of the fabricated films decreased with addition of plasticizers and further decreased with addition of different types of clays. The structural and morphological changes of the fabricated films in the presence of plasticizers and nanoclays were correlated in detail with their mechanical properties, crystallinity, biodegradability, thermal stability, and water absorption capacities.

Engineering bioinspired bacteria-adhesive clay nanoparticles with a membrane-disruptive property for the treatment of Helicobacter pylori infection

We present a bioinspired design strategy to engineer bacteria-targeting and membrane-disruptive nanoparticles for the effective antibiotic therapy of Helicobacter pylori (H. pylori) infection. Antibacterial nanoparticles were self-assembled from highly exfoliated montmorillonite (eMMT) and cationic linear polyethyleneimine (lPEI) via electrostatic interactions. eMMT functions as a bioinspired 'sticky' building block for anchoring antibacterial nanoparticles onto the bacterial cell surface via bacteria-secreted extracellular polymeric substances (EPS), whereas membrane-disruptive lPEI is able to efficiently lyse the bacterial outer membrane to allow topical transmembrane delivery of antibiotics into the intracellular cytoplasm. As a result, eMMT-lPEI nanoparticles intercalated with the antibiotic metronidazole (MTZ) not only efficiently target bacteria via EPS-mediated adhesion and kill bacteria in vitro, but also can effectively remain in the stomach where H. pylori reside, thereby serving as an efficient drug carrier for the direct on-site release of MTZ into the bacterial cytoplasm. Importantly, MTZ-intercalated eMMT-lPEI nanoparticles were able to efficiently eradicate H. pylori in vivo and to significantly improve H. pylori-associated gastric ulcers and the inflammatory response in a mouse model, and also showed superior therapeutic efficacy as compared to standard triple therapy. Our findings reveal that bacterial adhesion plays a critical role in promoting efficient antimicrobial delivery and also represent an original bioinspired targeting strategy via specific EPS-mediated adsorption. The bacteria-adhesive eMMT-lPEI nanoparticles with membrane-disruptive ability may constitute a promising drug carrier system for the efficacious targeted delivery of antibiotics in the treatment of bacterial infections.