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Percorrer por autor "Shoeib, Tamer"

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  • Aroma encapsulation for antibacterial and eco-friendly textile finishing
    Publication . Sharkawy, Asma; Fernandes, Isabel P.; Rodrigues, Alírio; Barreiro, M.F.; Shoeib, Tamer
    Encapsulation imparts new properties and added value to conventional fabrics. Most of the commercially available microcapsules for textile applications are made of melamine-formaldehyde, urea-formaldehyde or phenolformaldehyde resins, which have significant negative health and environmental effects. Recently, there has been a growing interest in the replacement of these resins with safe and environmentally benign materials. The process of fixing the microcapsules onto textile substrates is critical in ensuring their durability and effectiveness. The commonly known industrial methods used for this involve the use of two main groups of binders; polymeric resins, and polyfunctional crosslinking agents. Polymeric resins are reported to partially inhibit the release of fragrance from the microcapsules. The chemical cross-linkers are subdivided into formaldehyde based, e.g., formaldehyde and glutaraldehyde, and non-formaldehyde based, such as polycarboxylic acids. This work aimed at conferring fragrant and antibacterial properties to cotton fabrics employing new methodologies utilizing non-toxic and environmentally friendly materials.
    2017Documento de conferência Acesso aberto Ver mais
  • Aroma-loaded microcapsules with antibacterial activity for eco-friendly textile application: synthesis, characterization, release, and green grafting
    Publication . Sharkawy, Asma; Fernandes, Isabel P.; Barreiro, M.F.; Rodrigues, Alírio; Shoeib, Tamer
    Fragrant and antimicrobial properties were conferred to cotton fabrics following microencapsulation using green materials. Limonene and vanillin microcapsules were produced by complex coacervation using chitosan/gum Arabic as shell materials and tannic acid as hardening agent. The effect of two emulsifiers; Span 85 and polyglycerol polyricinoleate (PGPR), on the encapsulation efficiency (EE%), microcapsule’s size and morphology, and cumulative release profiles was studied. The mean diameter of the produced microcapsules ranged between 10.4 and 39.0 μm, whereas EE% was found to be between 90.4% and 100%. The use of Span 85 resulted in mononuclear morphology while PGPR gave rise to polynuclear structures, regardless of the core material (vanillin or limonene). The obtained microcapsules demonstrated a sustained release pattern; namely the total cumulative release of the active agents after 7 days at 37 ± 1 °C was 75%, 52% and 19.4% for the polynuclear limonene microcapsules, the mononuclear limonene microcapsules and the polynuclear vanillin microcapsules, respectively. Grafting of the produced microcapsules onto cotton fabrics through na esterification reaction using citric acid as a nontoxic cross-linker followed by thermofixation and curing, was confirmed by SEM and FTIR spectroscopy. Standard antibacterial assays conducted on both microcapsules alone and impregnated onto the fabrics indicated a sustained antibacterial activity.
    2017Artigo científico Acesso aberto Ver mais