Mats of PVA nanofibres were successfully prepared by the electrospinning process and were developed as carriers of drugs for a transdermal drug delivery system. Four types of non-steroidal anti-inflammatory drug with varying water solubility property, i.e. sodium salicylate (freely soluble in water), diclofenac sodium (sparingly soluble in water), naproxen (NAP), and indomethacin (IND) (both insoluble in water), were selected as model drugs. The morphological appearance of the drug-loaded electrospun PVA mats depended on the nature of the model drugs. The 1H-nuclear magnetic resonance results confirmed that the electrospinning process did not affect the chemical integrity of the drugs. Thermal properties of the drug-loaded electrospun PVA mats were analysed by differential scanning calorimetry and thermogravimetric analysis. The molecular weight of the model drugs played a major role on both the rate and the total amount of drugs released from the as-prepared drug-loaded electrospun PVA mats, with the rate and the total amount of the drugs released decreasing with increasing molecular weight of the drugs. Lastly, the drug-loaded electrospun PVA mats exhibited much better release characteristics of the model drugs than drug-loaded as-cast films.

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Recycled poly(ethylene terephthalate) from waste bottles (hereafter, rPET) was used as an reinforcing material for isotactic polypropylene (iPP) based on the concept of in situ microfibrillar-reinforced composites (iMFCs). Microfibers of rPET were successfully generated during melt-extrusion and subsequent drawing and preserved in the final injection-molded specimens. The effects of draw ratio, initial size of ground rPET flakes, and rPET content on morphological appearance of the extrudates and the as-formed rPET fibers and mechanical properties of the as-prepared iMFCs were investigated. The results showed that diameters of the asformed rPET fibers decreased with increasing draw ratio, and the initial size of ground rPET flakes did not affect the final diameters of the as-formed rPET fibers nor the mechanical properties of the as-prepared iMFCs. Flexural modulus, tensile modulus, and tensile strength of iPP/rPET iMFCs were improved by the presence of rPET microfibers and further improvement could be achieved by the addition of maleic anhydride-grafted iPP (PP-g-MA), which was used as the compatibilizer.

Cross-linking of electrospun (e-spun) fibre mats (beaded fibre morphology with the average diameter of the fibre segments between beads being ∼108 nm) of poly(vinyl alcohol) (PVA) containing sodium salicylate (SS), used as the model drug, was achieved by exposing the fibre mats to the vapour from 5.6 M aqueous solution of either glutaraldehyde or glyoxal for various exposure time intervals, followed by a heat treatment in a vacuum oven. With increasing the exposure time in the cross-linking chamber, the morphology of the e-spun fibre mats gradually changed from a porous to dense structure. Both the degree of swelling and the percentage of weight loss of the cross-linked fibre mats (i.e. ∼200–530% and ∼15–57%, respectively) were lower than those of the untreated ones (i.e. ∼610% and ∼67%, respectively). Cross-linking was also responsible for the monotonic increase in the storage moduli of the cross-linked SS-loaded e-spun PVA fibre mats with increasing exposure time in the cross-linking chamber. The release characteristic of the model drug from the SS-loaded e-spun PVA fibre mats both before and after cross-linking was assessed by the transdermal diffusion through a pig skin method. The cumulative release of the drug from these matrices could be divided into two stages: 0–4 and 4–72 h, in which the amount of SS released in the first stage increased very rapidly, while it was much slower in the second stage. Cross-linking slowed down the release of SS from the drug-loaded fibre mats appreciably and both the rate of release and the total amount of the drug released were decreasing functions of the exposure time interval in the cross-linking chamber. Lastly, the cross-linked SS-loaded e-spun PVA fibre mats were non-toxic to normal human dermal fibroblasts.

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