Incorporation of nanoparticles of titanium dioxide into thermoplastic textiles

The incorporation of nanoparticles (NPs) into the surfaces of materials has received significant attention, especially in the area of textiles for self-cleaning. The sphericity and fast oxidation of metallic NPs when exposed to atmosphere are factors that can complicate incorporation into textile substrates. Using unique photocatalytic properties to decompose bacteria cells, NPs of titanium dioxide (TiO2) are widely known as a common antimicrobial agent. The current research focuses on an innovative and novel coating process, where NPs of TiO2 have been incorporated by embedding on single-side of a textile fabric surface, while retaining exposure of the NPs to photon sources. This technique was linked with the surface modification of textiles by thermal heating of the surface, which initiated the reduction of the fabrics elastic modulus by surface-softening, then embedding NPs into the heated zone of the textile surface. The NPs were sufficiently embedded for durable adherence to the fabric surface, while retaining an optimum exposure to photon sources. Thermoplastic textiles, with a viscoelastic stage, permit recovery of its surface when heated below its melting temperature, Tm and were found to be an ideal material for this method of incorporation. The elastic modulus of polyethylene terephthalate (PET) textiles was investigated by thermodynamic experimental techniques, where the critical data was employed with two variant theories of contact mechanics. The study has found that embedding of NPs was better described by the JKR model due to its higher sensitivity to the reduction of the stiffness, the size of the NPs and the type of textile. Experimental rigs initiated the activation process for adherence of NPs to single-side of PET, cellulose acetate (CA) and acrylic thermoplastic polymer textiles. Analytical techniques, such as scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were employed to investigate the effective processing parameters of rigs. These properties included: quantitative and qualitative distribution of NPs on surfaces; durability of NPs to textiles; the textile transformation temperatures; and thermo-elastic responses. Film formation by agglomeration of NPs on textiles was noted where a higher concentration of TiO2 was applied. A Pull-Off technique was employed for the measurement of durability of NPs to textiles presenting insufficient quantities of Ti on the adhesive-tapes for a conclusive outcome. Mapping by EDS techniques was a method of quantifying the surface coverage of NPs on PET, with inconclusive outcomes. A standardised laundering procedure applied to textiles was a method of testing the durability of NPs to textiles, where an AAS instruments was sued to quantify the content of TiO2 (μg/cm2). The best optimised textile of PET was achieved for 76% retention of TiO2 between 1 and 40 laundering cycles. Empirical models were derived for the prediction of the optimum parameters for processing textiles by automatic rigs, and the prediction of TiO2 (μg/cm2) on PET. Automatic rigs were suitable to processing of thermoplastic textiles with NPs on single-side of its surface, and achieving increased retention where a reduction of the applied concentration and the higher surface heating was initiated. The outcomes of this study solve a major issue in the area of incorporation of NPs into textiles, by embedding NPs with high durability, and still exposing them for maximum antimicrobial abilities. The process has the potential for employment in the textile industry, for a cost effective method of preparing thermoplastic textiles providing efficient distribution and adherence of NPs on its surface, using inexpensive binding materials and processes.