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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.

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Abstract:The search for ideal biomaterials is still on-going for tissue regeneration. In this study, blends of Poly ε-caprolactone (PCL) with Poly l-lactic acid (PLLA), Nalidixic Acid (NA) and Polyethylene glycol (PEG) were prepared. Mechanical and thermal properties of the blends were investigated by tensile and flexural analysis, DSC, TGA, WXRD, MFI, BET, SEM and hot stage optical microscopy. Results showed that the loading of PLLA caused a significant decrease in tensile strength and almost total eradication of the elongation at break of PCL matrix, especially after PEG and NA addition. Increased stiffness was also noted with additional NA, PEG and PLLA, resulting in an increase in the flexural modulus of the blends.Isothermal degradation indicated that bulk PCL, PLLA and the blends were thermally stable at 200°C for the duration of 2h making extrusion of the blends at this temperature viable.Morphological study showed that increasing the PLLA content and addition of the very low viscosity PEG and powder NA decreased the Melt Flow Indexer and increased the viscosity.At the higher temperature the PLLA begins to soften and eventually melts allowing for increased flow and, coupling this with, the natural increase in MFI caused by temperature is enhanced further. The PEG and NA addition increased dramatically the pore volume which is important for cell growth and flow transport of nutrients and metabolic waste.

In this work, polypropylene (PP) nanocomposites containing different weight concentration of graphene nanoplatelets (GNP) were prepared by melt-mixing using an industrial-scale, co-rotating, intermeshing, twin-screw extruder. The materials were then compression moulded into sheets, and biaxially stretched at different stretching ratios (SRs) below the PP melting temperature. The effects of GNP content and biaxial stretching on the bulk properties of unfilled PP and PP/GNP nanocomposites have been investigated in details. Results show that the addition of GNP (>5wt%) can lead to electrically conductive composites due to the formation of percolation network. The GNP have led to increased polymer crystallinity and enhanced materials stiffness and strength. Biaxial stretching process further enhances the materials mechanical properties but has slightly decreased the composites electrical conductivity. The PP/GNP nanocomposites were also processed into 3D demonstrator parts using vacuum forming, and the properties of which were comparable with biaxially stretched composites.

Polyvinylchloride (PVC), polypropylene (PP), and low density polyethylene (LDPE)were used to prepare a range of wood-polymer blends containing 20, 40, and 60% w/w medium density fibreboard sawdust (90-150 microns and 212-850 microns In trod u c tionWood-polymer composites are a fascinating area in both polymers and wood, which arose due to a desire to recycle plastic and wood dust. When using the composites for outdoor applications it is necessary to balance the physical properties against water up-take. A wood-polymer composite with a high MFI polymer enhances properties but increases water up-take, whereas a low MFI polymer has reduced mechanical performance but an increased resistance to water up-take [ 11. Wood-filled polyethylene exhbits a greater degree of creep strain in freshwater than in air or saltwater [2]. Polyethylene-based wood composites reportedly offer a hgher degree of heat resistance with a heat distortion temperature of about 82OC at 264 psi, and they may also be somewhat less expensive than PVC formulations. The key advantage of PVC-based wood composites is their stainability or paintability. Little, if any, treatment is required for the stain or paint to adhere to the PVC-composite. It was found that for both cellular and solid PVC-composites, the moisture content should be kept in the 0.5-1% range. PVC-wood composites offer many advantages over conventional lumber. However, one of the major disadvantages is the increased density [3]. Other studies have used compatibilisers such as maleic anhydride and various processing aids to improve the mechanical properties and the water up-take of wood-polymer composites [4-61.When wood is compounded w i t h a polymer, the wood acts as a filler decreasing the mechanical properties. At high wood loadings there exists a non-continuous layer of polymer on the composite surface, and the associated disadvantage is water being absorbed into the matrix further decreasing the properties. Coupling agents are used in an attempt to convert wood filler into a reinforcing agent by creating chemical bonds between the wood surface and the polymer chains. Two commonly used coupling agents are maleic anhydride and titanates which are used to increase the composites mechanical properties. Coupling agents are molecular bridges at the interface between two substrates. Titanium-derived coupling agents are unique in that their reaction with the free protons in the inorganic interface results in the formation of organic monomolecular layers on the inorganic surface. Typically, titanate-treated inorganics are hydrophobic, organophilic and organofunctional. When incorporated into polymer systems they often have several effects, such as: promote adhesion; catalyse; improve dispersion and rheology; improve impact strength; do not create embrittlement; improve mechanical properties, and inhibit corrosion [7]. Titanates are able to crosslink or cure a variety of polymers such as polyolefin's, polystyrene, etc. During extrusion the effect of the titanate coupling agent is perman...